A flexible iron aluminate cement-based supercapacitor and its preparation method

Abstract

The present invention relates to a flexible iron aluminate cement-based supercapacitor and a preparation method thereof. The flexible iron aluminate cement-based supercapacitor is assembled with rGO / Ni as the positive electrode, rGO@α-Fe2O3 spindle / Ni as the negative electrode, and polyacrylamide-cement-emulsion-latex powder-water-KOH as the flexible cement-based solid electrolyte. Compared with the prior art, the flexible energy storage cement-based material, as a new type of building material integrating structure / function, realizes the integration of flexible lightweight design and functional technology. Its flexible characteristics can closely fit complex-shaped buildings and have good adaptability to special-shaped curved building structures. At the same time, a non-destructive construction process can also be adopted, and the energy storage function can be imparted to the existing structure by an external pasting method, so that the energy storage function can be imparted without structural reconstruction.

Description

Technical Field

[0001] The present invention relates to the field of supercapacitors, and particularly to a flexible iron aluminate cement-based supercapacitor and a preparation method thereof. Background Art

[0002] Large-sized supercapacitors based on cementitious materials not only have large-capacity energy storage and strong conversion functions, but can also serve as the main components of building structures, thus realizing the integration of structure / function. This new type of supercapacitor endows building structures with the additional function of green energy storage, and has advantages such as no geographical restrictions, rich raw materials, and low maintenance costs. Compared with commercial lithium-ion batteries, although the cement-based energy storage system is significantly lower in energy density, relying on the huge space advantage of building structures, this shortcoming can be effectively compensated by large-scale layout. In particular, this technical system shows advantages such as fast charge and discharge speed, long cycle service life, and strong safety in key performance indicators. However, existing rigid cement-based supercapacitors are not easily deformed and cannot meet the needs of the increasingly emerging special-shaped curved surface building projects, greatly limiting the application scenarios.

[0003] Existing rigid cement-based supercapacitors cannot fit perfectly with special-shaped curved surface buildings, while flexible cement-based supercapacitors have universality with special-shaped curved surface structures such as cylinders and curved walls or traditional plane structures, and can adopt non-destructive construction techniques to endow existing structures with energy storage functions through external pasting methods, realizing the ability to endow energy storage functions without structural reconstruction. Therefore, flexible cement-based supercapacitors provide a new path for the integration of the structure and function of building materials. Summary of the Invention

[0004] In order to solve the deficiency of poor adaptability of existing rigid cement-based supercapacitors to special-shaped building structures in the above-mentioned prior art and meet the urgent needs of the integration of curved surface building structures / functions, the present invention provides a flexible iron aluminate cement-based supercapacitor and a preparation method thereof.

[0005] The present invention is realized through the following technical solutions:

[0006] A flexible iron aluminate cement-based supercapacitor includes a flexible iron aluminate cement-based electrolyte and flexible electrodes; the flexible electrodes include an rGO / Ni positive electrode and an rGO@α-Fe2O3 spindle / Ni negative electrode.

[0007] Preferably, the flexible iron aluminate cement-based supercapacitor is assembled with rGO@α-Fe2O3 spindle / Ni as the negative electrode material, rGO / Ni as the positive electrode material, and polyacrylamide-emulsion-latex powder-water-KOH-iron aluminate cement as the flexible iron aluminate cement-based electrolyte.

[0008] Preferably, the preparation method of the rGO / Ni cathode is as follows: Ultrasonically disperse a certain mass of graphene oxide aerogel in a certain volume of deionized water, and then immerse nickel foam with a size of 10 mm 15 mm 1 mm into the ultrasonically suspended graphene oxide solution with uniform dispersion and continue ultrasonic treatment. After the ultrasonic treatment is completed, place it in a vacuum oven for drying. Finally, put the dried graphene oxide nickel foam into a reaction kettle for hydrothermal reaction, take it out, wash and dry to obtain the rGO / Ni cathode.

[0009] More preferably, the mass of the graphene oxide is 40 - 150 mg, the volume of the deionized water is 4 - 6 mL, the ultrasonic time is 3 - 6 min, the drying conditions are 60 °C and 2 h, and the hydrothermal reaction conditions are: add 60 mL of deionized water and 0.500 g of urea into a 100 mL reaction kettle, and react at 180 °C for 12 h.

[0010] Preferably, the preparation method of the rGO@α-Fe2O3 spindle / Ni anode is as follows: Place 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid and 30 mL of DMF into a reaction kettle, with a filling degree of 60%, and carry out hydrothermal reaction at 120 - 180 °C for 1 - 4 h to obtain the MIL-88-Fe precursor. Secondly, calcine the precursor in a muffle furnace at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, mix α-Fe2O3, carbon black, PVDF and N-methylpyrrolidone (NMP) in a mass ratio of 7:2:1:7, grind them into a slurry, coat it on the rGO / Ni electrode, dry, wash and dry again to obtain the rGO@α-Fe2O3 spindle / Ni anode.

[0011] Preferably, the preparation method of the flexible ferroaluminate cement-based electrolyte is as follows: Mix a polymer conductive monomer, ammonium persulfate, emulsion, latex powder, deionized water, KOH and ferroaluminate cement by stirring to obtain a flexible ferroaluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain a flexible ferroaluminate cement-based electrolyte for mechanical property testing, and use the other part to prepare a flexible ferroaluminate cement-based supercapacitor for testing electrochemical properties. Ammonium persulfate is used as an initiator to polymerize the polymer monomer into a polymer. The deionized water in the raw materials is only used to dissolve ammonium persulfate; the water required for the hydration of ferroaluminate cement is provided by the water in the PA emulsion.

[0012] More preferably, the polymer conductive monomer is acrylamide (AM).

[0013] More preferably, the dosage of the polymer conductive monomer is 10 - 30% of the mass of the ferroaluminate cement.

[0014] More preferably, the dosage of ammonium persulfate is 4% of the mass of AM.

[0015] More preferably, the emulsion is a PA (polyacrylate) emulsion with a water content of 50%, and the dosage is 150 - 250% of the mass of cement.

[0016] More preferably, the addition amount of the latex powder is 1% of the mass of cement.

[0017] More preferably, the mass of water is 1000% of the mass of ammonium persulfate.

[0018] More preferably, the mass of KOH is 6% of the mass of cement.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention first applies flexible ferroaluminate cement to supercapacitor electrolyte materials, realizing the flexibility of the energy storage system, enabling the energy storage device to adapt to the installation requirements of curved or special-shaped structures, and having both structural and energy storage functions;

[0021] 2. By introducing ferroaluminate cement rich in Fe 3+ The present invention promotes the Faraday reaction at the electrode - electrolyte interface, effectively enhancing the pseudocapacitance performance of the device;

[0022] 3. The present invention uses rGO@α-Fe2O3 spindle / Ni as the iron-modified negative electrode material. Through the synergistic effect of Fe2O3 spindle with a higher specific surface area and active sites and rGO, the electrochemical performance of the supercapacitor is greatly improved, achieving the goal of high specific capacitance;

[0023] 4. Using ammonium persulfate as an initiator, the present invention enables in-situ polymerization of polymer monomers under the condition of heat release during cement hydration, forming a three-dimensional network structure, optimizing its electrical conductivity while ensuring the mechanical strength of the flexible cement;

[0024] 5. The present invention realizes an integrated process of structural materials and energy storage functions in the preparation method, simplifies the device construction process, and has good scalability and engineering application prospects;

[0025] 6. Through comparative experiments, the present invention systematically optimizes the proportions of raw materials such as ferroaluminate cement, emulsion, and latex powder and the electrolyte thickness, screens out the optimal performance combination, and clarifies the synergistic enhancement mechanism between the iron-based electrode and ferroaluminate cement, providing a new energy storage solution for green buildings and intelligent infrastructure. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a flowchart for the preparation of the flexible ferroaluminate cement-based supercapacitor of the present invention;

[0027] Figure 2 Schematic diagram of the structure of the flexible iron aluminate cement-based supercapacitor of the present invention;

[0028] Figure 3 Comparison chart of cyclic voltammetry curves (CV) of the electrochemical performance tests of Examples 1-5 of the present invention;

[0029] Figure 4 Comparison chart of galvanostatic charge-discharge curves (GCD) of the electrochemical performance tests of Examples 1-5 of the present invention;

[0030] Figure 5 Comparison chart of electrochemical impedance spectra (EIS) of the electrochemical performance tests of Examples 1-5 of the present invention;

[0031] Figure 6 Comparison chart of cyclic voltammetry curves (CV) of the electrochemical performance tests of Example 2 and Comparative Examples 3 and 4 of the present invention;

[0032] Figure 7 Comparison chart of galvanostatic charge-discharge curves (GCD) of the electrochemical performance tests of Example 2 and Comparative Examples 3 and 4 of the present invention;

[0033] Figure 8 Comparison chart of cyclic voltammetry curves (CV) of the electrochemical performance tests of Example 2 and Comparative Examples 1 and 2 of the present invention;

[0034] Figure 9 Comparison chart of galvanostatic charge-discharge curves (GCD) of the electrochemical performance tests of Example 2 and Comparative Examples 1 and 2 of the present invention;

[0035] Figure 10 Comparison chart of electrochemical impedance spectra (EIS) of the electrochemical performance tests of Example 2 and Comparative Examples 1 and 2 of the present invention;

[0036] Figure 11 Comparison chart of tensile strength of the mechanical property tests of Examples 1-5 and Comparative Examples 1 and 2 of the present invention;

[0037] Figure 12 Schematic diagram of the flexible iron aluminate cement-based supercapacitor of Example 2 of the present invention lighting an LED lamp;

[0038] Figure 13Performance comparison chart of the flexible ferroaluminate cement of Example 2 of the present invention and traditional hard ferroaluminate cement, where (a) is the curvature radius measurement chart of the ferroaluminate flexible cement prepared in Example 2, (b) is the curvature radius measurement chart of the flexible ferroaluminate cement prepared in Example 2 from another angle, (c) is the thickness measurement of the flexible ferroaluminate cement of Example 2 and traditional hard ferroaluminate cement, (d) is the side length measurement of the flexible ferroaluminate cement of Example 2 and traditional hard ferroaluminate cement, (e) is the mass measurement of pure ferroaluminate cement, and (f) is the mass measurement of the flexible ferroaluminate cement prepared in Example 2 with the same size. Detailed implementation manners

[0039] The following will elaborate on the drawings and embodiments of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and specific implementation schemes and operation processes are given, but the protection scope of the present invention is not limited to the following embodiments.

[0040] A flexible ferroaluminate cement-based supercapacitor mainly includes rGO / Ni positive electrodes on both sides, rGO@α-Fe2O3 spindle / Ni negative electrodes, and a flexible ferroaluminate cement-based electrolyte in the middle. The flexible ferroaluminate cement-based electrolyte slurry is applied to the rGO / Ni positive electrode and then covered with the rGO@α-Fe2O3 spindle / Ni negative electrode, and fixed with parallel clamping plates at a certain interval. After curing and demolding, the flexible ferroaluminate cement-based supercapacitor can be obtained. The specific preparation process is shown in Figure 1 , and the structural schematic diagram of the prepared flexible ferroaluminate cement-based supercapacitor is shown in Figure 2 .

[0041] Preparation methods for the positive and negative electrodes of a flexible ferroaluminate supercapacitor, including the following steps:

[0042] (1) Place nickel foam with dimensions of 10 mm 15 mm 1 mm into a 10 - 25 mg / mL graphene oxide ultrasonic suspension for ultrasonic treatment to make graphene oxide evenly adhere to the surface and pores of the nickel foam. Then place it in a vacuum oven at 60 °C for drying for 2 h and take it out. Finally, put the nickel foam with evenly adhered graphene oxide into a 100 mL reaction kettle, add 0.500 g of urea and 60 mL of deionized water, and react at 180 °C for 12 h to obtain the rGO / Ni positive electrode;

[0043] (2) 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid, and 30 mL of DMF were placed into a reaction kettle with a filling degree of 60%, and hydrothermally reacted at 150 °C for 2 h to obtain the MIL-88-Fe precursor. Secondly, the precursor was calcined in a muffle furnace at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, α-Fe2O3, carbon black, PVDF, and N-methylpyrrolidone (NMP) were mixed and ground into a slurry according to a mass ratio of 7:2:1:7, and then coated on the rGO / Ni electrode obtained in step (1). After drying in a vacuum oven at 60 °C for 8 h, the rGO@α-Fe2O3 spindle / Ni negative electrode was obtained;

[0044] (3) The obtained electrodes were first washed 3 times with deionized water and then 3 times with alcohol, and then dried in a vacuum oven at 60 °C for 2 h to obtain the flexible rGO / Ni positive electrode and the rGO@α-Fe2O3 spindle / Ni negative electrode.

[0045] The raw materials of the flexible iron aluminate cement-based electrolyte are composed of ammonium persulfate, polymer conductive polymer monomer, emulsion, redispersible latex powder, deionized water, KOH, and iron aluminate cement according to a mass ratio of 4:(50~150):(750~1250):5:40:30:500.

[0046] The redispersible latex powder in the present invention is a redispersible latex powder, and any latex powder that can achieve the effect can be used.

[0047] Specifically, the preparation method of the flexible iron aluminate cement-based electrolyte includes the following steps:

[0048] (1) Weigh 50 g of iron aluminate cement, 5~15 g of polymer conductive polymer monomer, and 0.500 g of redispersible latex powder (Shanghai Badfu), and stir them evenly to obtain a powder material;

[0049] (2) Weigh 0.400 g of ammonium persulfate and dissolve it in deionized water to prepare a 10 wt% ammonium persulfate aqueous solution, and stir it evenly with 75~125 g of polyacrylate emulsion to obtain a liquid material;

[0050] (3) Mix and stir the powder material and the liquid material for 10 min, then add 3 g of KOH and continue to stir for 2 min to obtain the flexible iron aluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain the flexible iron aluminate cement-based electrolyte for mechanical property testing, and the other part is used to prepare the flexible iron aluminate cement-based supercapacitor for testing electrochemical performance.

[0051] The preparation method of the above flexible ferroaluminate cement-based supercapacitor includes: pouring an appropriate amount of flexible ferroaluminate cement-based electrolyte slurry onto the rGO / Ni positive electrode, placing the rGO@α-Fe2O3 spindle / Ni negative electrode on the upper layer, and using parallel clamping plates to control the electrolyte thickness to 2 mm to form a "sandwich" structure. Finally, it is placed in a curing chamber for curing to obtain a flexible ferroaluminate cement-based supercapacitor.

[0052] More specifically, the curing time is 28 d, the conditions of the curing chamber are 20±2 °C, and the relative humidity is controlled at 50±5%.

[0053] In the present invention: the specimens for electrochemical performance and mechanical performance tests are all cured in the curing chamber for 28 days.

[0054] The size of the flexible ferroaluminate cement-based electrolyte for testing electrochemical performance is 10 mm 10 mm 2 mm.

[0055] The size of the flexible cement-based electrolyte for testing mechanical performance is a dumbbell shape of 330 mm 60 mm 15 mm.

[0056] The flexible ferroaluminate cement-based supercapacitor needs to be immersed in 2M KOH solution for at least 2 h before testing its electrochemical performance.

[0057] The electrical performance tests mainly include cyclic voltammetry test (CV), galvanostatic charge-discharge test (GCD) and electrochemical impedance spectroscopy (EIS). When testing, the flexible ferroaluminate cement-based supercapacitor is taken out of the KOH solution and connected to the electrochemical workstation.

[0058] The DH7005 electrochemical workstation of Jiangsu Donghua Analytical Instrument Co., Ltd. is used for electrochemical performance testing. The cyclic voltammetry test can verify the cyclic information of the supercapacitor; the galvanostatic charge-discharge curve can directly obtain the specific capacitance of the sample; the electrochemical impedance spectroscopy can show the internal resistance of the supercapacitor. The scanning rate of the voltammetry test is 50 mV / s, the number of cycles is 5 times, and the charge-discharge current density is 1 mA / cm 2 ², and the number of cycles is 2 times. Before testing, the flexible ferroaluminate cement-based supercapacitor is immersed in 2M KOH for at least 2 hours.

[0059] For the rest of the raw materials or processing technologies without special instructions, it means that they are all conventional commercially available products or conventional processing technologies in this field. The rGO mentioned in the examples is reduced graphene oxide.

[0060] Example 1

[0061] A preparation method of a flexible iron aluminate cement-based supercapacitor, including the preparation of flexible electrodes, the preparation of flexible iron aluminate cement-based electrolytes, and the assembly of flexible iron aluminate cement-based supercapacitors. The final specifications are 10 mm 10 mm 2 mm of flexible iron aluminate cement-based electrolyte and 10 mm 15 mm 1 mm of flexible electrodes assembled, which is only used for subsequent electrochemical performance tests. The size is 330 mm 60 mm 15 mm of dumbbell-shaped flexible iron aluminate cement-based electrolyte is used for mechanical property tests, and the same applies to the following examples. The specific steps of this example are as follows:

[0062] (I) Preparation of flexible electrodes:

[0063] (1) Place a foam nickel with dimensions of 10 mm 15 mm 1 mm into an ultrasonic suspension of graphene oxide at 15 mg / mL and ultrasonicate to evenly attach graphene oxide to the surface and pores of the foam nickel. Then place it in a vacuum oven at 60 °C and dry for 2 h, and then take it out. Then put the foam nickel with evenly attached graphene oxide into a 100 mL reaction kettle, add 0.500 g of urea, and react at 180 °C for 12 h to obtain an rGO / Ni positive electrode;

[0064] (2) Place 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid, and 30 mL of DMF into a reaction kettle with a filling degree of 60%, and perform a hydrothermal reaction at 150 °C for 2 h to obtain a MIL-88-Fe precursor. Put the precursor into a muffle furnace and calcine at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, mix α-Fe2O3, carbon black, PVDF, and N-methylpyrrolidone (NMP) in a mass ratio of 7:2:1:7, grind them into a slurry, coat it on the rGO / Ni electrode obtained in step (1), and dry it in a vacuum oven at 60 °C for 8 h and then take it out to obtain an rGO@α-Fe2O3 spindle / Ni negative electrode;

[0065] (3) Wash the electrodes obtained in the above steps (1) and (2) 3 times with deionized water and then 3 times with alcohol, and then place them in a vacuum oven at 60 °C and dry for 2 h to obtain flexible positive / negative electrodes;

[0066] (II) Preparation of flexible iron aluminate cement-based electrolytes:

[0067] (1)Weigh 50 g of ferroaluminate cement, 5 g of polymer conductive polymer monomer AM, and 0.500 g of latex powder (Shanghai Badfu), and stir them evenly to obtain a powder material;

[0068] (2)Weigh 0.400 g of ammonium persulfate, dissolve it in deionized water, prepare a 10 wt% ammonium persulfate aqueous solution, and stir it evenly with 100 g of PA emulsion with a water content of 50% to obtain a liquid material;

[0069] (3)Mix and stir the powder material and the liquid material for 10 min, then add 3 g of KOH and continue to stir for 2 min to obtain a flexible ferroaluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain a flexible ferroaluminate cement-based electrolyte for mechanical property testing, and the other part is used to prepare a flexible ferroaluminate cement-based supercapacitor for testing electrochemical properties;

[0070] (III)Assembly of the flexible ferroaluminate cement-based supercapacitor:

[0071] Cover the flexible ferroaluminate cement-based electrolyte slurry on the rGO / Ni positive electrode, place the rGO@α-Fe2O3 spindle / Ni negative electrode on the upper layer, and use parallel clamping plates to control the electrolyte thickness to 2 mm to form a "sandwich" structure. Finally, place it in a curing room at a temperature of 20±2 °C and a relative humidity of 50±5% for curing for 28 days to obtain a flexible ferroaluminate cement-based supercapacitor.

[0072] Example 2

[0073] Example 2 provides another preparation method of a flexible ferroaluminate cement-based supercapacitor, and the specific operation steps are as follows:

[0074] (I)Preparation of the flexible electrode:

[0075] (1)Place nickel foam with dimensions of 10 mm 15 mm 1 mm into a 15 mg / mL graphene oxide ultrasonic suspension for ultrasonic treatment to make graphene oxide evenly adhere to the surface and pores of the nickel foam. Then place it in a vacuum oven at 60 °C for drying for 2 h and take it out. Then put the nickel foam with evenly adhered graphene oxide into a 100 mL reaction kettle, add 0.500 g of urea, and react at 180 °C for 12 h to obtain the rGO / Ni positive electrode;

[0076] (2) 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid and 30 mL of DMF were placed into a reaction kettle with a filling degree of 60%, and hydrothermal reaction was carried out at 150 °C for 2 h to obtain the MIL-88-Fe precursor. The precursor was placed into a muffle furnace and calcined at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, α-Fe2O3, carbon black, PVDF and N-methylpyrrolidone (NMP) were mixed and ground into a slurry according to the mass ratio of 7:2:1:7, and the slurry was coated on the rGO / Ni electrode obtained in step (1). After drying in a vacuum oven at 60 °C for 8 h, the rGO@α-Fe2O3 spindle / Ni negative electrode was obtained;

[0077] (3) The electrodes obtained in the above steps (1) and (2) were first washed 3 times with deionized water and then 3 times with alcohol, and then placed in a vacuum oven and dried at 60 °C for 2 h to obtain flexible positive / negative electrodes;

[0078] (II) Preparation of flexible ferroaluminate cement-based electrolyte:

[0079] (1) Weigh 50 g of ferroaluminate cement, 10 g of polymer conductive polymer monomer AM, and 0.500 g of latex powder (Shanghai Badfu), and stir them evenly to obtain a powder;

[0080] (2) Weigh 0.400 g of ammonium persulfate, dissolve it in deionized water, prepare a 10 wt% ammonium persulfate aqueous solution, and stir it evenly with 100 g of PA emulsion with a water content of 50% to obtain a liquid material;

[0081] (3) After mixing and stirring the powder and the liquid material for 10 min, add 3 g of KOH and continue to stir for 2 min to obtain a flexible ferroaluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain a flexible ferroaluminate cement-based electrolyte for mechanical property testing, and the other part is used to prepare a flexible ferroaluminate cement-based supercapacitor for testing electrochemical performance;

[0082] (III) Assembly of flexible ferroaluminate cement-based supercapacitor:

[0083] The flexible ferroaluminate cement-based electrolyte slurry was covered on the rGO / Ni positive electrode, and the rGO@α-Fe2O3 spindle / Ni negative electrode was placed on the upper layer. The thickness of the electrolyte was controlled to be 2 mm with parallel clamping plates to form a "sandwich" structure. Finally, it was placed in a curing chamber at a temperature of 20±2 °C and a relative humidity of 50±5% for curing for 28 days to obtain a flexible ferroaluminate cement-based supercapacitor.

[0084] Example 3

[0085] Example 3 provides another preparation method of a flexible iron aluminate cement-based supercapacitor, and the specific operation steps are as follows:

[0086] (I) Preparation of a flexible electrode:

[0087] (1) Place nickel foam with dimensions of 10 mm × 15 mm × 1 mm into an ultrasonic suspension of graphene oxide at 15 mg / mL and ultrasonically treat it to uniformly attach graphene oxide to the surface and pores of the nickel foam. Then, place it in a vacuum oven and dry it at 60 °C for 2 h and take it out. Then, put the nickel foam with uniformly attached graphene oxide into a 100 mL autoclave, add 0.500 g of urea, and react at 180 °C for 12 h to obtain an rGO / Ni positive electrode;

[0088] (2) Place 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid, and 30 mL of DMF into an autoclave with a filling degree of 60%, and carry out a hydrothermal reaction at 150 °C for 2 h to obtain a MIL-88-Fe precursor. Place the precursor in a muffle furnace and calcine it at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, mix α-Fe2O3, carbon black, PVDF, and N-methylpyrrolidone (NMP) in a mass ratio of 7:2:1:7, grind them into a slurry, coat it on the rGO / Ni electrode obtained in step (1), and dry it in a vacuum oven at 60 °C for 8 h and take it out to obtain an rGO@α-Fe2O3 spindle / Ni negative electrode;

[0089] (3) Wash the electrodes obtained in the above steps (1) and (2) 3 times with deionized water and then 3 times with alcohol, and then place them in a vacuum oven and dry them at 60 °C for 2 h to obtain flexible positive / negative electrodes;

[0090] (II) Preparation of a flexible iron aluminate cement-based electrolyte:

[0091] (1) Weigh 50 g of iron aluminate cement, 15 g of high molecular conductive polymer monomer AM, and 0.500 g of latex powder (Shanghai Badfu), and stir them evenly to obtain a powder material;

[0092] (2) Weigh 0.400 g of ammonium persulfate, dissolve it in deionized water, prepare a 10 wt% ammonium persulfate aqueous solution, and stir it evenly with 100 g of PA emulsion with a water content of 50% to obtain a liquid material;

[0093] (3) Mix the powder and liquid material and stir for 10 min, then add 3 g of KOH and continue to stir for 2 min to obtain a flexible iron-aluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain a flexible iron-aluminate cement-based electrolyte for mechanical property testing, and the other part is used to prepare a flexible iron-aluminate cement-based supercapacitor for testing electrochemical properties.

[0094] (III) Assembly of the flexible iron-aluminate cement-based supercapacitor:

[0095] Cover the flexible iron-aluminate cement-based electrolyte slurry on the rGO / Ni positive electrode, place the rGO@α-Fe2O3 spindle / Ni negative electrode on the upper layer, and use parallel clamping plates to control the electrolyte thickness to 2 mm to form a "sandwich" structure. Finally, place it in a curing chamber at a temperature of 20 ± 2 °C and a relative humidity of 50 ± 5% for curing for 28 days to obtain a flexible iron-aluminate cement-based supercapacitor.

[0096] Example 4

[0097] Example 4 provides another preparation method of a flexible iron-aluminate cement-based supercapacitor, and the specific operation steps are as follows:

[0098] (I) Preparation of the flexible electrode:

[0099] (1) Place nickel foam with dimensions of 10 mm 15 mm 1 mm into a 15 mg / mL graphene oxide ultrasonic suspension for ultrasonic treatment to make graphene oxide uniformly adhere to the surface and pores of the nickel foam. Then take it out after drying in a vacuum oven at 60 °C for 2 h. Then put the nickel foam with uniformly adhered graphene oxide into a 100 mL reaction kettle, add 0.500 g of urea, and react at 180 °C for 12 h to obtain the rGO / Ni positive electrode.

[0100] (2) Put 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid, and 30 mL of DMF into a reaction kettle with a filling degree of 60%, and carry out a hydrothermal reaction at 150 °C for 2 h to obtain a MIL-88-Fe precursor. Calcinate the precursor in a muffle furnace at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, mix α-Fe2O3, carbon black, PVDF, and N-methylpyrrolidone (NMP) in a mass ratio of 7:2:1:7, grind them into a slurry, coat it on the rGO / Ni electrode obtained in step (1), and take it out after drying in a vacuum oven at 60 °C for 8 h to obtain the rGO@α-Fe2O3 spindle / Ni negative electrode.

[0101] (3) Wash the electrodes obtained in the above steps (1) and (2) three times with deionized water and then three times with alcohol, and then place them in a vacuum oven at 60 °C for 2 h to obtain flexible positive / negative electrodes;

[0102] (II) Preparation of flexible ferroaluminate cement-based electrolyte:

[0103] (1) Weigh 50 g of ferroaluminate cement, 10 g of polymer conductive polymer monomer AM, and 0.500 g of latex powder (Shanghai Badfu) and stir them evenly to obtain a powder;

[0104] (2) Weigh 0.400 g of ammonium persulfate and dissolve it in deionized water to prepare a 10 wt% ammonium persulfate aqueous solution, and then stir it evenly with 75 g of PA emulsion with a water content of 50% to obtain a liquid material;

[0105] (3) Mix and stir the powder and the liquid material for 10 min, then add 3 g of KOH and continue to stir for 2 min to obtain a flexible ferroaluminate cement-based electrolyte slurry. Pour a part of the slurry into a mold for curing to obtain a flexible ferroaluminate cement-based electrolyte for mechanical property testing, and the other part is used to prepare a flexible ferroaluminate cement-based supercapacitor for testing electrochemical properties;

[0106] (III) Assembly of flexible ferroaluminate cement-based supercapacitor:

[0107] Cover the flexible ferroaluminate cement-based electrolyte slurry on the rGO / Ni positive electrode, place the rGO@α-Fe2O3 spindle / Ni negative electrode on the upper layer, and use parallel clamping plates to control the thickness of the electrolyte to 2 mm to form a "sandwich" structure. Finally, place it in a curing chamber at a temperature of 20 ± 2 °C and a relative humidity of 50 ± 5% for curing for 28 days to obtain a flexible ferroaluminate cement-based supercapacitor.

[0108] Example 5

[0109] Example 5 provides another preparation method of a flexible ferroaluminate cement-based supercapacitor, and the specific operation steps are as follows:

[0110] (I) Preparation of flexible electrodes:

[0111] (1) Place the nickel foam with dimensions of 10 mm 15 mm 1 mm into a 15 mg / mL graphene oxide ultrasonic suspension for ultrasonic treatment to make graphene oxide evenly adhere to the surface and pores of the nickel foam. Then take it out after drying in a vacuum oven at 60 °C for 2 h. Then place the nickel foam with evenly adhered graphene oxide into a 100 mL reaction kettle, add 0.500 g of urea, and react at 180 °C for 12 h to obtain the rGO / Ni positive electrode;

[0112] (2) 0.374 g of FeCl3·6H2O, 0.310 g of terephthalic acid and 30 mL of DMF were placed into a reaction kettle with a filling degree of 60%, and hydrothermal reaction was carried out at 150 °C for 2 h to obtain the MIL-88-Fe precursor. The precursor was placed in a muffle furnace and calcined at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, α-Fe2O3, carbon black, PVDF and N-methylpyrrolidone (NMP) were mixed and ground into a slurry according to the mass ratio of 7:2:1:7, and the slurry was coated on the rGO / Ni electrode obtained in step (1). After drying in a vacuum oven at 60 °C for 8 h, the rGO@α-Fe2O3 spindle / Ni negative electrode was obtained;

[0113] (3) The electrodes obtained in the above steps (1) and (2) were first washed 3 times with deionized water and then 3 times with alcohol, and then placed in a vacuum oven and dried at 60 °C for 2 h to obtain flexible positive / negative electrodes;

[0114] (II) Preparation of flexible ferroaluminate cement-based electrolyte:

[0115] (1) Weigh 50 g of ferroaluminate cement, 10 g of polymer conductive polymer monomer AM, and 0.500 g of latex powder (Shanghai Badfu) and stir them evenly to obtain a powder material;

[0116] (2) Weigh 0.400 g of ammonium persulfate and dissolve it in deionized water to prepare a 10 wt% ammonium persulfate aqueous solution, and stir it evenly with 125 g of PA emulsion with a water content of 50% to obtain a liquid material;

[0117] (3) The powder material and the liquid material were mixed and stirred for 10 min, and then 3 g of KOH was added and stirred for another 2 min to obtain a flexible ferroaluminate cement-based electrolyte slurry. Part of the slurry was poured into a mold for curing to obtain a flexible ferroaluminate cement-based electrolyte for mechanical property testing, and the other part was used to prepare a flexible ferroaluminate cement-based supercapacitor for testing electrochemical performance;

[0118] (III) Assembly of flexible ferroaluminate cement-based supercapacitor:

[0119] The flexible ferroaluminate cement-based electrolyte slurry was covered on the rGO / Ni positive electrode, and the rGO@α-Fe2O3 spindle / Ni negative electrode was placed on the upper layer. The thickness of the electrolyte was controlled to be 2 mm with parallel clamping plates to form a "sandwich" structure. Finally, it was placed in a curing chamber at a temperature of 20±2 °C and a relative humidity of 50±5% for curing for 28 days to obtain a flexible ferroaluminate cement-based supercapacitor.

[0120] Comparative Example 1

[0121] It is basically the same as the preparation method of Example 2, except that: when preparing the electrolyte, sulfoaluminate cement is used for the cement.

[0122] Comparative Example 2

[0123] It is basically the same as the preparation method of Example 2, except that: when preparing the electrolyte, 42.5 Portland cement is used for the cement.

[0124] Comparative Example 3

[0125] It is basically the same as the preparation method of Example 2, except that: pure nickel foam is used for both the positive and negative electrodes.

[0126] Comparative Example 4

[0127] It is basically the same as the preparation method of Example 2, except that: nickel foam attached with rGO is used for both the positive and negative electrodes.

[0128] The specific capacitance of the flexible cement-based supercapacitor is calculated by the following formula:

[0129]

[0130] Among them, I (mA) represents the current during the charge and discharge process, t (s) represents the discharge time, S (cm 2 ) represents the area of the contact part between the electrode and the electrolyte, V (V) is the size of the charge and discharge voltage window.

[0131] Figure 3 are the CV curves of the flexible iron aluminate cement-based supercapacitors of Examples 1-5. It can be seen from the figure that the CV curve area of the device in Example 2 is the largest, proving that its energy storage performance is the best. Figure 4 、 Figure 5 are the GCD curves and EIS impedance spectra of the flexible iron aluminate cement-based supercapacitors of Examples 1-5 respectively. From Figure 4 it can be seen that the discharge time of the device in Example 2 is the longest, and its specific capacitance is the largest (161.125 mF / cm 2 ) among the five examples. From Figure 5 it can be seen that the internal resistance of the device in Example 2 is the smallest (34.42 Ω), further indicating that the device in Example 2 has better electrochemical performance.

[0132] Figure 6 are the CV curves of Example 2 and Comparative Examples 3 and 4. It can be seen from the figure that as rGO and α-Fe2O3 spindles are successively loaded, the area of the CV curve increases successively, which is related to the increase in the specific surface area and the increase in active sites of the electrode material.

[0133] Figure 7Figure 2 shows the EIS charge-discharge curves of Example 2 and Comparative Examples 3 and 4. It can be seen from the figure that as rGO and α-Fe2O3 spindles are successively loaded, the discharge duration of the flexible iron aluminate cement-based supercapacitor increases successively, with Example 2 being the highest (161.125 mF / cm 2 ), followed by Comparative Example 4 (48.75 mF / cm 2 ), and Comparative Example 3 being the lowest (9.375 mF / cm 2 ). This once again proves that the combination of rGO and α-Fe2O3 spindles can improve the performance of the electrode.

[0134] Figure 8 , Figure 9 and Figure 10 Figure 3 shows the comparison of the electrochemical performance of Example 2 and Comparative Examples 1 and 2. It can be seen from Figure 8 that the CV curve of Example 2 is the most saturated, indicating its better electrochemical performance; Figure 9 it can be seen that under the same conditions, the flexible iron aluminate cement-based supercapacitor has better electrochemical performance (161.13 mF / cm 2 ) compared to the flexible silicate cement-based supercapacitor (86.94 mF / cm 2 ) and the flexible sulphoaluminate cement-based supercapacitor (88.05 mF / cm 2 ). From the EIS impedance spectrum diagram of Figure 10 , it can be seen that the internal resistance of the flexible silicate cement-based supercapacitor is the largest (104.60 Ω), the internal resistance of the flexible sulphoaluminate cement-based supercapacitor is the smallest (16.69 Ω), and although the internal resistance of the flexible iron aluminate cement-based supercapacitor (34.42 Ω) is slightly larger than that of the flexible sulphoaluminate cement-based supercapacitor, the flexible iron aluminate cement-based supercapacitor still has a higher specific capacitance per unit area due to the synergistic effect of its rGO@α-Fe2O3 spindle / Ni negative electrode and flexible iron aluminate cement-based electrolyte.

[0135] Figure 11 Figure 4 shows the comparison of the tensile strength in the mechanical property tests of Examples 1-5 and Comparative Examples 1 and 2 of the present invention. It can be seen that the flexible iron aluminate cement-based electrolyte of Example 2 has excellent multifunctionality as its mechanical property does not decrease significantly while having excellent electrical performance.

[0136] Figure 12 Figure 5 shows a schematic diagram of the flexible iron aluminate cement-based supercapacitor of Example 2 lighting an LED lamp. After being formed and bent into an arch shape, the flexible iron aluminate cement-based supercapacitor device of Example 2 can light an LED lamp for 13 minutes and 32 seconds after being charged for 10 minutes.

[0137] Figure 13The measurement results show that the flexible ferroaluminate cement prepared according to the ratio of Embodiment 2 of the present invention has excellent flexibility and lightweight properties. The minimum curvature radius of this cement can reach 15 mm, as shown in Figure 13 in (a) and (b); for the traditional hard ferroaluminate cement of the flexible ferroaluminate cement with the same size, as shown in Figure 13 in (c) and (d), the flexible ferroaluminate cement has a lighter mass (87% of the hard cement), as shown in Figure 13 in (e) and (f).

[0138] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: within the scope of the spirit and essence defined by the claims of the present invention, the technical solutions recorded in the foregoing embodiments can be modified, or some or all of the technical features can be equivalently replaced; and these modifications or replacements are still within the scope defined by the claims of the present invention.

Claims

1. A flexible ferroaluminate cement-based supercapacitor, characterized in that, It includes a flexible iron aluminate cement-based electrolyte and flexible electrodes; the flexible electrodes include an rGO / Ni positive electrode and an rGO@α-Fe2O3 spindle / Ni negative electrode; The preparation method of the flexible iron aluminate cement-based electrolyte is as follows: the raw materials are composed of ammonium persulfate, a polymer conductive polymer monomer, an emulsion, a latex powder, deionized water, KOH, and iron aluminate cement in a mass ratio of 4:50-150:750-1250:5:40:30:

500. First, stir the iron aluminate cement, the polymer conductive polymer monomer, and the latex powder into a uniform powder. Mix ammonium persulfate with deionized water to make an ammonium persulfate aqueous solution, then stir it with the emulsion into a uniform liquid material. Then mix and stir the powder and the liquid material, add KOH and stir evenly again to obtain a flexible iron aluminate cement-based electrolyte slurry. Pour the slurry into a mold and place it in a curing chamber at a temperature of 20±2 °C and a relative humidity of 50±5% for curing to obtain the flexible iron aluminate cement-based electrolyte.

2. The flexible iron aluminate cement-based supercapacitor according to claim 1, characterized in that, The polymer conductive polymer monomer is acrylamide.

3. A flexible iron aluminate cement-based supercapacitor according to claim 1, characterized in that The emulsion is a polyacrylate emulsion with a water content of 50%.

4. The flexible iron aluminate cement-based supercapacitor according to claim 1, wherein The water-cement ratio of the flexible iron aluminate cement-based electrolyte slurry is 0.75-1.

25.

5. A flexible iron aluminate cement-based supercapacitor according to claim 1, characterized in that The thickness of the flexible iron aluminate cement-based electrolyte is 2 mm.

6. The flexible iron aluminate cement-based supercapacitor according to claim 1, characterized in that, The preparation method of the rGO / Ni positive electrode is as follows: soak nickel foam with dimensions of 10 mm*15 mm*1 mm in a graphene oxide ultrasonic suspension with a concentration of 10-25 mg / mL, continuously ultrasonic for 3-6 minutes, take it out and dry it, then place it in a reaction kettle, add 0.500 g of urea at 180 °C and react for 10-20 h, take it out, wash and dry to obtain the rGO / Ni positive electrode.

7. A flexible iron aluminate cement-based supercapacitor according to claim 1, characterized in that, The preparation method of the rGO@α-Fe2O3 spindle / Ni negative electrode is as follows: first, place 0.374 g of FeCl3·6H2O, dimethylformamide, and 0.310 g of terephthalic acid in a reaction kettle, and perform a hydrothermal reaction at 120-180 °C for 1-4 h to obtain a MIL-88-Fe precursor. Then place the precursor in a muffle furnace and calcine it at 400 °C for 2 h to obtain α-Fe2O3 spindles. Finally, mix and grind the α-Fe2O3 spindles, carbon black, PVDF, and N-methylpyrrolidone in a mass ratio of 7:2:1:7 into a slurry, coat it on the rGO / Ni electrode, dry it, wash it, and dry it again to obtain the rGO@α-Fe2O3 spindle / Ni negative electrode.

8. A preparation method of a flexible iron aluminate cement-based supercapacitor according to any one of claims 1-7, characterized in that, It includes the following steps: Cover the rGO / Ni positive electrode with the flexible iron aluminate cement-based electrolyte slurry, place the rGO@α-Fe2O3 spindle / Ni negative electrode on the upper layer, and use parallel clamping plates to control the electrolyte thickness to 2 mm to form a "sandwich" structure. Finally, place it in a curing chamber at a temperature of 20±2 °C and a relative humidity of 50±5% for curing to obtain a flexible iron aluminate cement-based supercapacitor.

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