A structural supercapacitor based on redox cement-based solid electrolyte and its preparation method

Abstract

The present invention relates to a structural supercapacitor based on a redox cement-based solid electrolyte and a preparation method thereof. The structural supercapacitor uses rGO / Mn2O3 as a positive electrode, rGO as a negative electrode, and polyacrylamide-cement-Mn(NO3) 2· 4H2O is assembled from a redox solid electrolyte. First, rGO / Mn2O3 electrodes are prepared by a two-step hydrothermal method. Secondly, a redox cement-based solid electrolyte is prepared by a synchronous reaction method. Finally, the electrodes prepared above are assembled with the electrolyte to prepare a structural supercapacitor. Compared with the prior art, the present invention prepares solid electrolytes by a synchronous reaction method, fully utilizes the heat released during the cement hydration process to initiate the polymer monomers, and forms a 3D through-network structure inside the solid electrolyte, which balances the contradiction between its mechanical properties and electrochemical properties to a certain extent. In addition, by adding Mn to the solid electrolyte 2+ The contribution of solid electrolytes to the specific capacitance of structural supercapacitors was realized.

Description

Technical Field

[0001] The present invention relates to the technical field of structural energy storage materials, and in particular to a structural supercapacitor based on a redox cement-based solid electrolyte and a preparation method thereof. Background Art

[0002] Looking at the current composition of energy consumption, building energy consumption accounts for over 30% of total energy consumption. my country's energy source remains primarily based on traditional thermal power generation, which not only exacerbates the global energy shortage but also releases gases from fossil fuel combustion that cause severe environmental pollution. To alleviate the increasing shortage of fossil fuels like coal, oil, and natural gas, and the severe environmental pollution caused by combustion gases like CO2, CO, and NO2, some experts have proposed the concept of Zero-Energy Buildings (ZEBs), aiming to reduce total energy consumption by lowering building energy consumption. This requires combining energy efficiency with renewable energy generation and vigorously developing green and clean renewable energy. While wind, solar, and hydropower generation have continued to increase in recent years, limited local resources have limited the flexibility of regional power systems and are significantly affected by seasonal and climate fluctuations. Consequently, many researchers are focusing on the development of new energy storage devices, aiming to develop a new type of multifunctional energy storage device that can both function as a building structure and store energy.

[0003] Supercapacitors have attracted much attention due to their good cycle stability and high power density. Currently, research on supercapacitors is mostly focused on gel solid-state supercapacitors and liquid supercapacitors. Although gel solid-state supercapacitors have a certain tensile strength, their low ionic conductivity and compressive strength limit their application. Although liquid supercapacitors have high electrochemical performance, their electrolytes are usually organic solvents such as ethylene carbonate and propylene carbonate. These electrolytes are not only toxic and pose certain risks to human health during the production process, but also have safety issues such as flammability and explosiveness, and are also greatly restricted during use. At the same time, the recycling and treatment of discarded capacitors is also a very arduous task.

[0004] Structural supercapacitors have the dual functions of mechanical load and electrical energy storage. An important component of structural supercapacitors is solid electrolytes. The choice of solid electrolytes will greatly limit the application areas of structural supercapacitors. Generally, for solid electrolytes, two aspects of performance are mainly concerned; (1) Strength. For structural supercapacitors to be used in the field of building structures, it is essential to have a certain strength. As the most common cement-based material in the field of civil engineering, it has become the first choice for studying solid electrolytes. (2) Ionic conductivity. Ionic conductivity directly affects the migration speed of ions. When the ionic conductivity is too low, many ions cannot participate in the reaction during the charging and discharging process, which will lead to low ion utilization, too low energy density of structural supercapacitors, and too little actual application value. Summary of the Invention

[0005] The purpose of the present invention is to provide a structural supercapacitor based on a redox cement-based solid electrolyte and a preparation method thereof, which balances the mechanical properties and ionic conductivity of the solid electrolyte to a certain extent.

[0006] The purpose of the present invention can be achieved through the following technical solution: a structural supercapacitor based on a redox cement-based solid electrolyte, comprising a redox cement-based solid electrolyte and a structural electrode; the structural electrode is an rGO electrode and an rGO@Mn2O3 electrode.

[0007] Preferably, the structural supercapacitor is composed of rGO / Mn2O3 as the positive electrode, rGO as the negative electrode, and polyacrylamide-cement-Mn(NO3) 2· 4H2O is assembled from a redox solid electrolyte. First, rGO / Mn2O3 electrodes are prepared by a two-step hydrothermal method. Secondly, a redox cement-based solid electrolyte is prepared by a simultaneous reaction method. Finally, the prepared electrodes and electrolyte are assembled to prepare a structural supercapacitor.

[0008] Preferably, the method for preparing the redox cement-based solid electrolyte comprises: mixing and stirring an aqueous ammonium persulfate solution, an aqueous high molecular weight conductive polymer monomer solution, a redox reaction raw material solution, water, and cement to obtain the redox cement-based solid electrolyte. The ammonium persulfate is an initiator.

[0009] Further preferably, the high molecular conductive polymer monomer is acrylamide (AM).

[0010] Further preferably, the content of the high molecular conductive polymer monomer is 10% of the base cement content.

[0011] Further preferably, the redox reaction raw material is Mn(NO3)2·4H2O. The present invention adds a certain substance capable of undergoing redox reaction to the solid electrolyte, so that it contributes to the specific capacitance of the structured supercapacitor, thereby achieving a synergistic effect between the electrode and the electrolyte.

[0012] More preferably, the dosage of the Mn(NO3)2·4H2O solution accounts for 0%, 2%, 4%, 6% and 8% of the mass of the benchmark cement respectively.

[0013] Further preferably, the cement is benchmark cement, and the cement slurry is prepared by controlling the water-cement ratio to 0.5.

[0014] Preferably, the preparation method of the redox cement-based solid electrolyte comprises the following steps:

[0015] (1) Weigh 7.5 g of ammonium persulfate and dissolve it in deionized water to prepare a 10 wt% ammonium persulfate aqueous solution;

[0016] (2) Weighing 20 g of high molecular weight conductive polymer monomer, dissolving it in a certain amount of deionized water, and stirring it on a magnetic stirrer to obtain a polymer monomer solution;

[0017] (3) Weigh 0-16 g of Mn(NO3)2·4H2O solution;

[0018] (4) After the above solution is mixed evenly, it is added together with water into a beaker containing 200 g of cement and stirred for 2 minutes to obtain a redox cement-based solid electrolyte.

[0019] Preferably, the preparation method of the rGO electrode comprises: applying suspended graphene oxide on the surface of nickel foam, taking it out after drying, continuing to apply graphene oxide suspension and then drying, repeating the operation, and then placing the nickel foam coated with graphene oxide in a reactor to react to obtain the rGO electrode.

[0020] More preferably, the reaction temperature is 160-200° C., and the reaction time is 16-20 h.

[0021] Preferably, the preparation method of the rGO@Mn2O3 electrode comprises: placing the rGO electrode in a reactor filled with Mn(NO3)2·4H2O and ethanol, and performing a hydrothermal reaction at 100-140°C for 8-12 hours to obtain the rGO@Mn2O3 electrode.

[0022] The method for preparing the positive and negative electrodes comprises the following steps:

[0023] (1) The suspended graphene oxide was applied to the surface of the nickel foam, and then placed in an oven and dried at 65°C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180°C for 18 h to obtain the rGO electrode.

[0024] (2) The rGO electrode obtained in step (1) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O solution and 60 ml of ethanol, and hydrothermally reacted at 120°C for 10 h to obtain the rGO@Mn2O3 electrode.

[0025] (3) The electrodes obtained in (1) and (2) above were washed with ethanol and deionized water three times each to remove excess impurities, and then dried in an oven at 65°C for 6 h.

[0026] In the present invention, the 50% Mn(NO3)2·4H2O solution is an aqueous solution with a mass fraction of Mn(NO3)2·4H2O of 50%.

[0027] The rGO electrode is based on nickel foam as the current collector, and graphene is loaded on the surface of nickel foam as the negative electrode. The rGO@Mn2O3 electrode is based on the negative electrode and subjected to solvent thermal loading of Mn2O3. The solvent thermal solution is 60ml of anhydrous ethanol and 5.72g of 50% Mn(NO3). 2· A mixed solution of 4H2O solution.

[0028] Preferably, the preparation method of the structural supercapacitor comprises: pouring a redox cement-based solid electrolyte into a mold with rGO electrodes and rGO@Mn2O3 electrodes inserted at both ends, curing, curing, and demolding to obtain a structural supercapacitor.

[0029] More preferably, the curing time is 26 to 30 days.

[0030] Preferably, the method for preparing the structural supercapacitor comprises the following steps:

[0031] The polymer monomer solution, initiator solution, Mn(NO₃)₂·4H₂O solution, cement, and water were stirred in a beaker to form a uniform, stable cement slurry. This slurry was then poured into a mold with rGO@Mn₂O₃ and rGO inserted at either end to assemble the supercapacitor. After curing at room temperature for 28 hours, the mechanical and electrochemical properties were tested.

[0032] The mold for testing the resistivity of the electrolyte and the assembly structure of the supercapacitor is a 1cm×1cm×1cm mold. When testing the ionic conductivity, the electrodes inserted on both sides of the cement slurry are steel sheets.

[0033] The mold for testing the mechanical properties of the electrolyte is a mold of 3cm×3cm×3cm.

[0034] The tests of mechanical properties and electrochemical properties were all carried out after curing at room temperature for 28 days.

[0035] The electrochemical performance test of the solid electrolyte mainly refers to the test of ionic conductivity.

[0036] During the electrochemical performance test of the structural supercapacitor, it is necessary to drop a reinforcing electrolyte into the electrolyte.

[0037] The strong electrolyte added during the test of the structural supercapacitor is a 5M KOH solution.

[0038] As a traditional building material, cement-based materials not only have high strength but also high porosity. On the one hand, this structure can be used to store more electrolytes, and on the other hand, it can provide more channels for the electron and ion migration process, so that more ions can play a role in the charging and discharging process. As a high molecular conductive polymer, polyacrylamide is added to cement-based materials in the form of monomers and initiators. On the one hand, it uses the heat released during the cement hydration process to initiate the polymerization reaction. On the other hand, it can form a conductive network structure inside the cement paste, thereby balancing the contradiction between the strength and conductivity of the solid electrolyte. In addition, by adding Mn(NO3) 2· 4H2O is added to the solid electrolyte to prepare a redox solid electrolyte, so that the solid electrolyte can make a certain contribution to the specific capacitance of the structural supercapacitor.

[0039] Compared with the prior art, the present invention has the following advantages:

[0040] 1. The present invention not only balances the contradiction between the mechanical properties and ionic conductivity of solid electrolytes to a certain extent, but also enables the solid electrolyte to make a certain contribution to the specific capacitance of the structural supercapacitor, thereby improving its energy storage capacity;

[0041] 2. This invention uses traditional cement-based materials as solid electrolytes, which not only have high strength and relatively high ionic conductivity, but also can be produced on a large scale, which is consistent with the large-volume characteristics of the construction industry.

[0042] 3. The present invention incorporates the polymer into the cement-based material in the form of monomers and initiators, thereby avoiding the problem of uneven polymer mixing and fully utilizing the heat released during the cement hydration process.

[0043] 4. The present invention adds high molecular weight polymers in the form of monomers and initiators to the solid electrolyte, which largely balances the contradiction between strength and ionic conductivity, so that the solid electrolyte has higher ionic conductivity while having higher strength;

[0044] 5. The present invention is to use Mn(NO3) 2· 4H2O was added to the solid electrolyte to obtain a redox solid electrolyte, which can make a certain contribution to the specific capacitance of the structural supercapacitor;

[0045] 6. The present invention prepares solid electrolytes by synchronous reaction method, fully utilizing the heat released during cement hydration process to initiate polymer monomers, forming a 3D through-linked network structure inside the solid electrolyte, which balances the contradiction between its mechanical properties and electrochemical properties to a certain extent. In addition, by adding Mn 2+ The contribution of solid electrolytes to the specific capacitance of structural supercapacitors was realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 Flow chart for the preparation of structural supercapacitors.

[0047] Figure 2 No Mn(NO3) added 2· SEM image of cement-based solid electrolyte in 4H2O solution ( Figure 2 a) Add 4% of the base cement mass of Mn(NO3) 2· SEM image of cement-based solid electrolyte in 4H2O solution ( Figure 2 b).

[0048] Figure 3 The compressive strength of the solid electrolyte prepared in Examples 1, 2, 3, 4 and Comparative Example 1 ( Figure 3 a) Ionic conductivity ( Figure 3 b) and multifunctional diagram ( Figure 3 c).

[0049] Figure 4 The specific capacitance of the structured supercapacitor prepared in Examples 1, 2, 3, 4 and Comparative Example 1 ( Figure 4 a, Figure 4 b) Rate performance ( Figure 4 c) and cyclic stability ( Figure 4 d). DETAILED DESCRIPTION

[0050] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operating processes, but the protection scope of the present invention is not limited to the following embodiments.

[0051] In the following examples, the mechanical properties test in this study refers to the compressive strength test performed using a concrete compression testing machine; the electrical properties test mainly refers to the electrochemical impedance spectroscopy (EIS) test and the galvanostatic charge-discharge (GCD) test performed using an electrochemical workstation.

[0052] Unless otherwise specified, the raw materials or technical treatments used are conventional commercially available raw materials or conventional processing techniques in this field.

[0053] Example 1

[0054] Preparation steps of redox solid electrolyte:

[0055] (11) Weigh 20 g of AM monomer and dissolve it in deionized water. Then stir it on a magnetic stirrer at room temperature until the AM monomer is completely dissolved.

[0056] (12) Weigh 4 g of 50% Mn(NO3)2·4H2O solution;

[0057] (13) Weigh 75 g of 10% APS solution;

[0058] (14) Weigh 200 g of standard cement, mix all the above solutions and pour them into the standard cement, control the water-cement ratio to 0.5, and stir for 2 minutes to form a uniform cement paste.

[0059] Electrode preparation steps:

[0060] (21) The suspended graphene oxide was applied to the surface of nickel foam, and then placed in an oven to dry at 65 °C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180 °C for 18 h to obtain an rGO electrode.

[0061] (22) The rGO electrode obtained in step (21) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O and 60 ml of anhydrous ethanol, and subjected to hydrothermal reaction at 120 °C for 10 h to obtain the rGO@Mn2O3 electrode;

[0062] (23) The electrodes obtained in (21) and (22) were washed three times with ethanol and three times with deionized water to remove excess impurities, and then dried in an oven at 65 °C for 6 h.

[0063] Assembly of structural supercapacitors:

[0064] (31) The cement paste was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm steel sheets were inserted on both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise. After KOH completely permeated the solid electrolyte, its ionic conductivity was tested;

[0065] (32) The cement slurry was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm electrodes based on nickel foam were inserted into both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise to test the electrochemical performance of the structural supercapacitor.

[0066] (33) The cement paste was poured into a 3 cm × 3 cm × 3 cm mold and cured at room temperature for 28 days before testing its compressive strength.

[0067] Example 2

[0068] Preparation steps of redox solid electrolyte:

[0069] (11) Weigh 20 g of AM monomer and dissolve it in deionized water. Then stir it on a magnetic stirrer at room temperature until the AM monomer is completely dissolved.

[0070] (12) Weigh 8g of 50% Mn(NO3) 2· 4H2O solution;

[0071] (13) Weigh 75 g of 10% APS solution;

[0072] (14) Weigh 200 g of standard cement, mix all the above solutions and pour them into the standard cement, control the water-cement ratio to 0.5, and stir for 2 minutes to form a uniform cement paste.

[0073] Electrode preparation steps:

[0074] (21) The suspended graphene oxide was applied to the surface of nickel foam, and then placed in an oven to dry at 65 °C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180 °C for 18 h to obtain an rGO electrode.

[0075] (22) The rGO electrode obtained in step (21) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O and 60 ml of anhydrous ethanol, and subjected to hydrothermal reaction at 120 °C for 10 h to obtain the rGO@Mn2O3 electrode;

[0076] (23) The electrodes obtained in (21) and (22) were washed three times with ethanol and three times with deionized water to remove excess impurities, and then dried in an oven at 65 °C for 6 h.

[0077] Assembly of structural supercapacitors:

[0078] (31) The cement paste was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm steel sheets were inserted on both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise. After KOH completely permeated the solid electrolyte, its ionic conductivity was tested;

[0079] (32) The cement slurry was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm electrodes based on nickel foam were inserted into both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise to test the electrochemical performance of the structural supercapacitor.

[0080] (33) The cement paste was poured into a 3 cm × 3 cm × 3 cm mold and cured at room temperature for 28 days before testing its compressive strength.

[0081] Example 3

[0082] Preparation steps of redox solid electrolyte:

[0083] (11) Weigh 20 g of AM monomer and dissolve it in deionized water. Then stir it on a magnetic stirrer at room temperature until the AM monomer is completely dissolved.

[0084] (12) Weigh 12g of 50% Mn(NO3) 2· 4H2O solution;

[0085] (13) Weigh 75 g of 10% APS solution;

[0086] (14) Weigh 200 g of standard cement, mix all the above solutions and pour them into the standard cement, control the water-cement ratio to 0.5, and stir for 2 minutes to form a uniform cement paste.

[0087] Electrode preparation steps:

[0088] (21) The suspended graphene oxide was applied to the surface of nickel foam, and then placed in an oven to dry at 65 °C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180 °C for 18 h to obtain an rGO electrode.

[0089] (22) The rGO electrode obtained in step (21) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O and 60 ml of anhydrous ethanol, and subjected to hydrothermal reaction at 120 °C for 10 h to obtain the rGO@Mn2O3 electrode;

[0090] (23) The electrodes obtained in (21) and (22) were washed three times with ethanol and three times with deionized water to remove excess impurities, and then dried in an oven at 65 °C for 6 h.

[0091] Assembly of structural supercapacitors:

[0092] (31) The cement paste was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm steel sheets were inserted on both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise. After KOH completely permeated the solid electrolyte, its ionic conductivity was tested;

[0093] (32) The cement slurry was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm electrodes based on nickel foam were inserted into both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise to test the electrochemical performance of the structural supercapacitor.

[0094] (33) The cement paste was poured into a 3 cm × 3 cm × 3 cm mold and cured at room temperature for 28 days before testing its compressive strength.

[0095] Example 4

[0096] Preparation steps of redox solid electrolyte:

[0097] (11) Weigh 20 g of AM monomer and dissolve it in deionized water. Then stir it on a magnetic stirrer at room temperature until the AM monomer is completely dissolved.

[0098] (12) Weigh 16g of 50% Mn(NO3) 2· 4H2O solution;

[0099] (13) Weigh 75 g of 10% APS solution;

[0100] (14) Weigh 200 g of standard cement, mix all the above solutions and pour them into the standard cement, control the water-cement ratio to 0.5, and stir for 2 minutes to form a uniform cement paste.

[0101] Electrode preparation steps:

[0102] (21) The suspended graphene oxide was applied to the surface of nickel foam, and then placed in an oven to dry at 65 °C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180 °C for 18 h to obtain an rGO electrode.

[0103] (22) The rGO electrode obtained in step (21) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O and 60 ml of anhydrous ethanol, and subjected to hydrothermal reaction at 120 °C for 10 h to obtain the rGO@Mn2O3 electrode;

[0104] (23) The electrodes obtained in (21) and (22) were washed three times with ethanol and three times with deionized water to remove excess impurities, and then dried in an oven at 65 °C for 6 h.

[0105] Assembly of structural supercapacitors:

[0106] (31) The cement paste was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm steel sheets were inserted on both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise. After KOH completely permeated the solid electrolyte, its ionic conductivity was tested;

[0107] (32) The cement slurry was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm electrodes based on nickel foam were inserted into both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise to test the electrochemical performance of the structural supercapacitor.

[0108] (33) The cement paste was poured into a 3 cm × 3 cm × 3 cm mold and cured at room temperature for 28 days before testing its compressive strength.

[0109] Comparative Example 1

[0110] Preparation steps of redox solid electrolyte:

[0111] (11) Weigh 20 g of AM monomer and dissolve it in deionized water. Then stir it on a magnetic stirrer at room temperature until the AM monomer is completely dissolved.

[0112] (12) Weigh 75 g of 10% APS solution;

[0113] (13) Weigh 200 g of standard cement, mix all the above solutions and pour them into the standard cement, control the water-cement ratio to 0.5, and stir for 2 minutes to form a uniform cement paste.

[0114] Electrode preparation steps:

[0115] (21) The suspended graphene oxide was applied to the surface of nickel foam, and then placed in an oven to dry at 65 °C for 20 min. After that, the surface was taken out and the graphene suspension was applied again and dried. The operation was repeated three times. The nickel foam coated with graphene was then placed in a 100 ml reactor and reacted at 180 °C for 18 h to obtain an rGO electrode.

[0116] (22) The rGO electrode obtained in step (21) was placed in a reactor containing 5.72 g of 50% Mn(NO3)2·4H2O and 60 ml of anhydrous ethanol, and subjected to hydrothermal reaction at 120 °C for 10 h to obtain the rGO@Mn2O3 electrode;

[0117] (23) The electrodes obtained in (21) and (22) were washed three times with ethanol and three times with deionized water to remove excess impurities, and then dried in an oven at 65 °C for 6 h.

[0118] Assembly of structural supercapacitors:

[0119] (31) The cement paste was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm steel sheets were inserted on both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise. After KOH completely permeated the solid electrolyte, its ionic conductivity was tested;

[0120] (32) The cement slurry was poured into a 1 cm × 1 cm × 1 cm mold, and 1 cm × 2 cm electrodes based on nickel foam were inserted into both sides. After curing at room temperature for 28 days, 5 M KOH was added dropwise to test the electrochemical performance of the structural supercapacitor.

[0121] (33) The cement paste was poured into a 3 cm × 3 cm × 3 cm mold and cured at room temperature for 28 days before testing its compressive strength.

[0122] The solid electrolyte ionic conductivity ρ is calculated by formula (1):

[0123]

[0124] ρ(S / cm) is the ionic conductivity, L(cm) is the thickness of the electrolyte, S(cm 2 ) is the contact area, R b (Ω) is the ohmic internal resistance of the solid electrolyte (specifically, the intersection with the abscissa in the EIS curve).

[0125] The specific capacitance C of the structural supercapacitor is calculated by formula (2):

[0126]

[0127] C(mF / cm 2 ) is the specific capacitance, I (mA / cm 2 ) is the current density during the charge and discharge process, ΔT(s) is the discharge time, and ΔV(V) is the voltage window for charge and discharge

[0128] Figure 2 a is a SEM image of the cement-based solid electrolyte prepared in Comparative Example 1, Figure 2b is an SEM image of the cement-based structured superelectrolyte prepared in Example 2. It can be observed from the figure that the addition of a small amount of Mn(NO3)2·4H2O helps to improve the density of the cement material, thereby increasing its strength. In addition, the PAM generated after the polymerization of AM can be used to improve the conductivity of the cement-based material.

[0129] Figure 3 The compressive strength of the solid electrolyte prepared in Examples 1, 2, 3, 4 and Comparative Example 1 ( Figure 3 a) Ionic conductivity ( Figure 3 b) and the multifunctional diagram of both ( Figure 3 c). As can be seen from the figure, the compressive strength of the redox solid electrolyte at all Mn(NO3)2·4H2O dosages is higher than that of the solid electrolyte without Mn(NO3)2·4H2O. Therefore, the addition of Mn(NO3)2·4H2O improves the mechanical properties of the solid electrolyte to a certain extent. As the Mn(NO3)2·4H2O solution content increases from 2% to 8%, the compressive strength shows a trend of first increasing and then decreasing (20.47-24.33-13.57 MPa). This may be due to the fact that a small amount of Mn(NO3)2·4H2O significantly promotes cement hydration. When the dosage is too high, this promoting effect weakens, resulting in a decrease in strength.

[0130] Furthermore, with increasing Mn(NO3)2·4H2O doping, the electrolyte's Rs shows a trend of first increasing and then decreasing (131.50-134.22-681.10Ω). When the Mn(NO3)2·4H2O solution content is 2%, the redox solid electrolyte's resistivity is a minimum of 131.50Ω, corresponding to a maximum conductivity of 7.60mS / cm. This improves the conductivity compared to the solid electrolyte without Mn(NO3)2·4H2O. However, when the Mn(NO3)2·4H2O solution content exceeds 4%, the ionic conductivity decreases significantly, possibly because excessive Mn(NO3)2·4H2O inhibits the synthesis of PAM.

[0131] It can be seen from the multifunctional graph of strength and ionic conductivity that when the Mn(NO3)2·4H2O solution content is 4%, the multifunctionality of the redox solid electrolyte is the best, corresponding to a compressive strength of 24.33MPa and an ionic conductivity of 7.45mS / cm.

[0132] Figure 4 The specific capacitance of the structured supercapacitor prepared in Examples 1, 2, 3, 4 and Comparative Example 1 ( Figure 4 a, 4b), rate performance ( Figure 4 c) and cyclic stability ( Figure 4 d) From Figure 4 a and Figure 4 As can be seen in b, when Mn(NO3)2·4H2O is not doped, the discharge time of the structural supercapacitor is only 25.62s. Therefore, its surface capacitance is low, only 15.07mF / cm 2 , which is significantly lower than the other four groups. This is mainly because, for the structural supercapacitor without Mn(NO3)2·4H2O, the Faradaic reaction during discharge is only provided by the active electrode material, while the Faradaic reaction of the other four groups also comes from the redox solid electrolyte, so the specific capacitance is higher. Figure 4 As can be seen from Figure c, as the current density decreases, the discharge time continues to extend, and the pseudocapacitive characteristics of the discharge process become more and more obvious. 2 Reduced to 0.2 mA / cm 2 When the surface capacitance is increased from the original 93.40mF / cm 2 Gradually increased to 164.38mF / cm 2 The rate performance under high current is obviously better than that under low current. Figure 4 As can be seen in Figure d, after 2000 cycles, the surface capacitance increases to 109.16% of the original value. Not only does it not decay, but it increases to a certain extent, which shows that its cycle stability is good.

[0133] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A structural supercapacitor based on a redox cement-based solid electrolyte, characterized in that: It includes a redox cement-based solid electrolyte and a structural electrode; the structural electrode is an rGO electrode and an rGO@Mn2O3 electrode; The preparation method of the redox cement-based solid electrolyte comprises: mixing and stirring an ammonium persulfate aqueous solution, a high molecular conductive polymer monomer aqueous solution, a redox reaction raw material solution, water and cement to obtain a redox cement-based solid electrolyte; The polymer conductive polymer monomer is acrylamide; The cement is the base cement, and the water-cement ratio is controlled to be 0.5 to prepare the cement paste; The redox reaction raw material solution is an aqueous solution with a mass fraction of Mn(NO3)2·4H2O of 50%, and the amount of the Mn(NO3)2·4H2O solution accounts for 4% of the mass of the benchmark cement.

2. The structural supercapacitor based on redox cement-based solid electrolyte according to claim 1, characterized in that: The content of the high molecular conductive polymer monomer is 10% of the cement content.

3. The structural supercapacitor based on redox cement-based solid electrolyte according to claim 1, characterized in that: The preparation method of the rGO electrode includes: applying suspended graphene oxide to the surface of nickel foam, removing it after drying, continuing to apply graphene oxide suspension and then drying, repeating the operation, and then placing the nickel foam coated with graphene oxide in a reactor to react to obtain the rGO electrode.

4. The structural supercapacitor based on redox cement-based solid electrolyte according to claim 3, characterized in that: The reaction temperature is 160-200° C., and the reaction time is 16-20 hours.

5. The structural supercapacitor based on redox cement-based solid electrolyte according to claim 1, characterized in that: The preparation method of the rGO@Mn2O3 electrode comprises: placing the rGO electrode in a reactor filled with Mn(NO3)2·4H2O and ethanol, and performing a hydrothermal reaction at 100-140°C for 8-12 hours to obtain the rGO@Mn2O3 electrode.

6. The structural supercapacitor based on redox cement-based solid electrolyte according to claim 1, characterized in that: The preparation method of the structural supercapacitor includes: pouring a redox cement-based solid electrolyte into a mold with rGO electrodes and rGO@Mn2O3 electrodes inserted at both ends respectively, curing, curing, and demolding to obtain a structural supercapacitor.

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