1. A preparation method of a high-strength self-healing hydrogel electrolyte is characterized by comprising the following steps:

1) preparing a prepolymer solution:

dissolving methacrylamide, acrylic acid and potassium persulfate in deionized water to prepare a uniform solution as a prepolymer solution;

2) preparation of poly (methacrylamide-co-acrylic acid) hydrogel: introducing argon gas into the prepolymer solution, injecting the solution into a mold, placing the mold in a constant temperature box, heating for polymerization, forming a hydrogel film after the polymerization is finished, taking out the hydrogel film from the mold, and soaking the hydrogel film in deionized water until the hydrogel film reaches a swelling equilibrium state with constant mass to obtain poly (methacrylamide-co-acrylic acid) hydrogel;

3) preparation of poly (methacrylamide-co-acrylic acid) hydrogel electrolyte:

respectively preparing salt solutions, and soaking the prepared poly (methacrylamide-co-acrylic acid) hydrogel in the salt solutions until a swelling equilibrium state with constant mass is achieved, thereby obtaining the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane.

2. The method for preparing a high-strength self-healing hydrogel electrolyte according to claim 1, wherein the method comprises the following steps: in the prepolymer solution of 1), the total concentration of two monomers of methacrylamide and acrylic acid in the solution is 3-8mol/L, the molar ratio of the methacrylamide to the acrylic acid is 8:2-2:8, and the content of potassium persulfate is 0.3-2% of the total amount of the two monomers.

3. The method for preparing a high-strength self-healing hydrogel electrolyte according to claim 1, wherein the method comprises the following steps: and 2), introducing high-purity argon into the prepolymer solution for 15-60min, injecting the solution into a mold to form a thickness of about 1mm, and heating and polymerizing in a constant temperature box at 60-80 ℃ for 4-10 h.

4. The method for preparing a high-strength self-healing hydrogel electrolyte according to claim 1, wherein the method comprises the following steps: in the step 3), the salt solution is one of sodium chloride, potassium chloride and lithium chloride, and the concentration of the salt solution is 1-10 mol/L.

5. A high-strength self-healing hydrogel electrolyte is characterized in that: prepared by the preparation method of any one of claims 1 to 4.

6. A preparation method of a flexible supercapacitor is characterized by comprising the following steps: after preparing the hydrogel electrolyte membrane according to any one of claims 1 to 4, the following steps are carried out:

4) preparing a mask:

designing a snake-shaped interdigital electrode structure, determining the geometric parameters of the snake-shaped interdigital electrode structure, and printing the designed snake-shaped interdigital electrode structure on a film through a laser printer to manufacture a mask plate;

5) preparing a flexible supercapacitor:

cutting the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane obtained in the step 3) into a size the same as that of a mask plate, covering the mask plate on the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane, and coating graphene slurry on the surface of the mask plate to form a patterned electrode;

after the graphene slurry is solidified, coating a layer of silver-silver chloride slurry on the surface of the solidified graphene slurry to serve as a current collector;

tearing off the mask plate, solidifying the silver-silver chloride slurry at normal temperature, leading out two leads from the positive electrode and the negative electrode of the electrode with the snake-shaped interdigital electrode structure, and respectively attaching a layer of polyacrylate adhesive tape on the upper surface and the lower surface of the integral structure for packaging to obtain the flexible supercapacitor.

7. The method for preparing a flexible supercapacitor according to claim 6, wherein the method comprises the following steps:

the snake-shaped interdigital electrode structure is characterized in that each finger and each finger arm in the interdigital electrode structure are snake-shaped, and the snakes of the fingers are arranged in parallel.

8. A high-strength self-healing hydrogel electrolyte is characterized in that: prepared by the preparation method of any one of claims 6 to 7.

Background

The super capacitor is a novel energy storage device with electrochemical performance between a battery and a traditional capacitor, the power density of the super capacitor is higher than that of the battery, the energy density of the super capacitor is higher than that of the traditional capacitor, the super capacitor has the advantages of short charging and discharging time, high power density, long service life, environmental friendliness, energy conservation and the like, and has huge application prospects in the fields of smart power grids, new energy automobiles, transportation, intelligent instruments, electronic products, national defense, communication and the like.

In recent years, with the continuous pursuit of technical innovation and high-tech products, the development of miniaturized, portable, and wearable electronic devices has attracted more and more attention. For example: electronic newspapers, smart clothing, electronic skins, flexible displays, flexible smartphones, and implantable medical devices. When the super capacitor is used as an energy storage system of the devices, the super capacitor not only needs to be supplied with power, but also has the advantages of flexibility, foldability and stretchability. On the one hand, the supercapacitor is flexible enough to cope with any deformation of the device and to ensure that the electrochemical properties do not change with the deformation of the device. On the other hand, the super capacitor also has certain strength and toughness to resist external force damage and bear deformation.

Disclosure of Invention

In order to solve the problems in the background art, the invention aims at the problems that most of chemical gel electrolytes used by the flexible super capacitor can not be recovered and reconstructed after being damaged, the physical gel electrolyte has weak mechanical strength and the like, and prepares a high-strength physical gel electrolyte which can bear large load and deformation and is beneficial to repair and reconstruction.

The poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane prepared by the method has the advantages of high toughness, flexibility and self-healing, and the prepared flexible super capacitor has the advantages of high toughness, stretchability and flexibility.

As shown in fig. 8, the technical solution adopted by the present invention is:

a preparation method of a high-strength self-healing hydrogel electrolyte comprises the following steps:

1) preparing a prepolymer solution:

dissolving methacrylamide, acrylic acid and potassium persulfate in deionized water to prepare a uniform solution as a prepolymer solution;

2) preparation of poly (methacrylamide-co-acrylic acid) hydrogel: introducing argon gas into the prepolymer solution, injecting the solution into a mold, placing the mold in a constant temperature box, heating for polymerization, forming a hydrogel film after the polymerization is finished, taking out the hydrogel film from the mold, and soaking the hydrogel film in deionized water until the hydrogel film reaches a swelling equilibrium state with constant mass to obtain poly (methacrylamide-co-acrylic acid) hydrogel;

the hydrogel film can be gradually swelled after being soaked in deionized water, the mass is increased, and when the mass is increased to constant weight, a swelling equilibrium state is achieved.

3) Preparation of poly (methacrylamide-co-acrylic acid) hydrogel electrolyte:

respectively preparing salt solutions, and soaking the prepared poly (methacrylamide-co-acrylic acid) hydrogel in the salt solutions until a swelling equilibrium state with constant mass is achieved, thereby obtaining the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane.

In the prepolymer solution of 1), the total concentration of two monomers of methacrylamide and acrylic acid in the solution is 3-8mol/L, the molar ratio of the methacrylamide to the acrylic acid is 8:2-2:8, and the content of potassium persulfate is 0.3-2% of the total amount of the two monomers.

And 2), introducing high-purity argon into the prepolymer solution for 15-60min, injecting the solution into a mold to form a thickness of about 1mm, and heating and polymerizing in a constant temperature box at 60-80 ℃ for 4-10 h. The high purity is more than 99.9 percent.

In the step 3), the salt solution is one of sodium chloride, potassium chloride and lithium chloride, preferably potassium chloride, and the concentration of the salt solution is 1-10 mol/L. The concentration of the salt solution prepared by sodium chloride, potassium chloride and lithium chloride is different.

The poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane has the characteristics of high strength, flexibility and self-healing, the electric conductivity is 1.9-2.8S/m, the water content is 21-35 wt%, the tensile breaking elongation is 670-1180%, the tensile breaking stress is 0.3-0.4MPa, the Young modulus is 0.2-0.3MPa, and the tearing energy is 540-²。

Secondly, the high-strength self-healing hydrogel electrolyte is prepared by a preparation method.

Thirdly, a preparation method of the flexible super capacitor comprises the following steps:

after the hydrogel electrolyte membrane is prepared, the following steps are carried out:

4) preparing a mask:

designing a snake-shaped interdigital electrode structure in AutoCAD, determining geometric parameters of the snake-shaped interdigital electrode structure, wherein the geometric parameters comprise pattern shapes, arrangement and the like, and printing the designed snake-shaped interdigital electrode structure on a film through a high-resolution laser printer to manufacture a mask plate; the mask plate is of a structure with a hollow pattern groove, and the hollow pattern is the shape of the snake-shaped interdigital electrode structure.

5) Preparing a flexible supercapacitor:

cutting the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane obtained in the step 3) into a rectangle with the same size as that of a mask, wherein the cut rectangle is 30mm multiplied by 18mm in size, covering the mask on the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane, and coating graphene slurry on the surface of the mask to form a patterned electrode;

after the graphene slurry is solidified, coating a layer of silver-silver chloride slurry on the surface of the solidified graphene slurry to serve as a current collector;

tearing off the mask plate, solidifying the silver-silver chloride slurry at normal temperature, leading out two leads from the positive and negative electrodes of the electrode with the snake-shaped interdigital electrode structure, and respectively sticking a layer of silver-silver chloride slurry on the upper and lower surfaces of the integral structurePolyacrylateAnd (3) packaging by using an adhesive tape, wherein the polyacrylate adhesive tape is used for preventing water evaporation, namely, a layer of polyacrylate adhesive tape is respectively adhered to the bottom surface of the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane and the surface of the solidified silver-silver chloride slurry, so that the high-strength physical hydrogel electrolyte membrane flexible supercapacitor is obtained.

The snake-shaped interdigital electrode structure is characterized in that each finger and each finger arm in the interdigital electrode structure are snake-shaped, and the snakes of the fingers are arranged in parallel.

The flexible super capacitor has the characteristics of high strength, stretchability and flexibility. The specific ratio of the radius of the outer arc to the radius of the inner arc of the electrode is 0.3-0.8, and the bending angle of the snake-shaped electrode is 60-180 degrees. When the flexible super capacitor is applied with 0.05-0.30mA/cm²The maximum area capacitance of the capacitor is 0.5-2.5mF/cm²The energy density can reach 40-170 mu Wh/cm²The power density is 45000-150000 muW/cm²。

In a first aspect of the present invention, there is provided a high strength, flexible, self-healing physical hydrogel comprising monomeric methacrylamide, acrylic acid, a thermal initiator potassium persulfate, and deionized water, wherein the high strength, flexible, self-healing hydrogel has a ratio of the amounts of the two monomeric methacrylamide and acrylic acid species in the hydrogel of between about 2:8 and about 8: 2.

In one embodiment of the poly (methacrylamide-co-acrylic acid) hydrogel according to the invention, the high strength, flexible, self-healing poly (methacrylamide-co-acrylic acid) hydrogel is free of chemical cross-linking agents, is a gel formed by cross-linking two monomers of methacrylamide and acrylic acid through non-covalent bonds (hydrogen bonds), and has good mechanical properties (tensile young's modulus, tensile breaking stress, tensile breaking elongation, tearing energy) and self-healing properties.

The hydrogel film has good mechanical properties, and the prepared hydrogel has the tensile mode modulus of 0.2MPa, the tensile breaking stress of 0.3MPa, the tensile breaking elongation of 1400 percent and the tearing energy of 360J/m by taking the components with the mass ratio of the methacrylamide to the acrylic acid of 7:13 as an example²。

The hydrogel film obtained had good transparency, and had a transmittance of 89% for the component having a molar ratio of methacrylamide to acrylic acid monomer of 7: 13.

The second aspect of the invention is to provide a preparation method of the high-strength self-healing conductive hydrogel electrolyte. The method is to soak the hydrogel film obtained in the first aspect of the invention in deionized water for 36-72h to a swelling equilibrium. Then soaking the electrolyte in 4mol/L potassium chloride solution for 12-36h to prepare the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte.

Test results show that the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane prepared by the method has the conductivity of 1.9-2.8S/m, the tensile breaking elongation of 670-1180%, the tensile breaking stress of 0.3-0.4MPa, the Young modulus of 0.2-0.3MPa and the breaking energy of 640-750J/m²。

The poly (methacrylamide-co-acrylic acid) hydrogel electrolyte membrane prepared by the method has good stretchability, self-healing property and conductivity, and the hydrogel electrolyte with excellent performance is used for preparing a flexible stretchable super capacitor.

The flexible super capacitor prepared by the invention takes high-strength self-healing hydrogel as electrolyte, and in order to improve the tensile property of the capacitor, the capacitor electrode is designed into an interdigital electrode with a snake-shaped structure. The electrode material adopts graphene which has extremely high performance at normal temperatureElectron mobility, and high mechanical elasticity and strength by covalent bonding in a honeycomb lattice arrangement. And finally, packaging the prepared capacitor by using a polyacrylate adhesive tape. The prepared flexible super capacitor not only can be bent and stretched, but also has excellent electrochemical properties. When the flexible super capacitor is at 0.1mA/cm²When the current density of (2) is applied, the maximum area capacitance is 2mF/cm²The energy density can reach 160 mu Wh/cm²The power density was 48000. mu. Wh/cm²。

The supercapacitor with the interdigital configuration does not influence equivalent series resistance due to the thickness of the electrodes, the distance between the two electrodes is not influenced by the thickness of electrolyte, and the supercapacitor has a shorter ion diffusion path, can quickly diffuse ions and further improves the performance of the capacitor. The supercapacitor formed by the interdigital electrodes can be bent, but the stretching is influenced by the interdigital electrodes. The finger-shaped interdigital electrode is specially designed into a snake shape in structure, so that the tensile property of the super capacitor is improved.

Compared with the prior art, the beneficial effects of the invention are embodied in the following aspects:

the hydrogel prepared by the invention does not contain a chemical cross-linking agent, has good safety, no toxicity or harm, and is environment-friendly;

the hydrogel electrolyte membrane with excellent conductivity can be obtained by soaking the hydrogel membrane in an inorganic salt solution, and the preparation method is simple and convenient;

the hydrogel electrolyte membrane prepared by the invention is crosslinked in a non-covalent bond (hydrogen bond) mode, not only has higher Young modulus (0.2-0.3MPa) and ultrahigh tensile property (1180%), but also shows excellent self-healing performance under the condition of normal temperature, and the electrolyte membrane can be recovered and reconstructed;

the hydrogel flexible supercapacitor constructed by the method has the advantages of high strength, stretchability and flexibility, and the influence of equivalent series resistance is reduced by introducing the graphene interdigital electrode, so that ions are rapidly diffused, and the electrical performance of the flexible supercapacitor is improved;

according to the hydrogel flexible supercapacitor constructed by the method, a diaphragm does not need to be added when the supercapacitor is assembled by using electrolyte, so that the manufacturing process is simplified; and the raw materials and the structure for preparing the super capacitor device are simple, the production cost is reduced, and the mass production and the manufacture of the flexible super capacitor are facilitated.

Drawings

FIG. 1 is a flow chart of the preparation of poly (methacrylamide-co-acrylic acid) hydrogel.

Fig. 2(a) shows a hydrogel solution, and fig. 2(b) shows a mold.

Fig. 3 is a diagram of a hydrogel electrolyte membrane.

Fig. 4 is a drawing of a tensile test object of the hydrogel electrolyte membrane.

Fig. 5(a) is a tensile stress-strain graph, fig. 5(b) is a tear strength graph, and fig. 5(c) is a conductivity graph.

Fig. 6(a) is a diagram of a hydrogel electrolyte substance before self-healing, fig. 6(b) is a diagram of a hydrogel electrolyte substance after self-healing, and fig. 6(c) is a diagram of a hydrogel electrolyte substance after self-healing when nippers are clamped.

Fig. 7 is a graph of the dimensions of a serpentine interdigital electrode.

Fig. 8 is a flow chart of flexible supercapacitor fabrication.

Figure 9 is a graph of the results for the flexible supercapacitor.

FIG. 10 is a flexible supercapacitor bend diagram.

Fig. 11 is a graph of the results for a flexible supercapacitor stretched from 0% to 100%.

Detailed Description

For the purpose of facilitating an understanding of the technical solutions, objects, and advantages of the present invention, the present invention will be further described with reference to the accompanying drawings and specific examples.

In the invention, a universal tensile testing machine with LEGEND 2345 model is adopted to characterize the mechanical property of the hydrogel film; the electrochemical performance of the flexible supercapacitor prepared by the method is tested by adopting an electrochemical impedance method, a cyclic voltammetry method and a constant current method. The procedure for testing these properties and the method of preparing the relevant splines will be illustrated with specific examples. The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the examples but rather encompasses equivalent technical solutions to those skilled in the art in view of the inventive concept.

The examples of the invention are as follows:

example 1

In this example, it was found through experiments that the optimal mole fraction ratio of methacrylamide to acrylic acid in the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte prepared from methacrylamide and acrylic acid with different mole fractions is 7: 13. As shown in fig. 1, the preparation method of the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte with a molar fraction ratio of methacrylamide to acrylic acid of 7:13 is as follows:

(1) dissolving methacrylamide and acrylic acid in deionized water, wherein the mole fraction ratio of the methacrylamide to the acrylic acid is 7:13, adding a small amount of potassium persulfate, wherein the amount of the potassium persulfate accounts for 1% of the total amount of the methacrylamide and the acrylic acid, and then placing the mixed solution on a magnetic stirrer for fully stirring.

(2) And (2) introducing argon gas into the solution obtained in the step (1) for 30min, and exhausting dissolved oxygen in the solution to obtain the hydrogel solution shown in the figure 2 (a).

(3) The solution was injected into a mold (fig. 2(b)) by a syringe, and the mold was placed in an oven at 60 ℃ and heated for polymerization for 7 hours, and then taken out, and the resulting hydrogel film was immersed in deionized water for 36 hours, and sufficiently absorbed water to reach an equilibrium state.

(4) The prepared poly (methacrylamide-co-acrylic acid) hydrogel is soaked in 4mol/L potassium chloride solution to be saturated to form a poly (methacrylamide-co-acrylic acid) hydrogel electrolyte, as shown in figure 3.

The poly (methacrylamide-co-acrylic acid) hydrogel electrolyte prepared by the method has excellent mechanical property and electrical property, the electrical conductivity is 2.8S/m, the tensile elongation at break is 1180%, the tensile stress at break is 0.4MPa, the Young modulus is 0.3MPa, and the breaking energy is 750J/m²。

A. Tensile mechanical Property test

In this example, the tensile mechanical properties of the preferred high-strength self-healing hydrogel electrolyte prepared in the above examples were characterized:

(1) the poly (methacrylamide-co-acrylic acid) hydrogel is fished out from the potassium chloride electrolyte solution, the water on the surface is wiped dry, and a rectangular sample strip with the length of 40mm and the width of 6mm is cut from the hydrogel film. The thickness and initial length of the bar are measured with a vernier caliper.

(2) The hydrogel film sample obtained in step (1) was loaded on a universal tensile testing machine (Instron) model LEGEND 2345 and subjected to tensile test at a rate of 100mm/min at room temperature, as shown in FIG. 4.

(3) Each fraction was tested in 5 replicates. The tensile stress-strain curve was recorded and the Young's modulus was calculated by taking the slope of the initial strain less than 10% as shown in FIG. 5.

Tests show that the Young modulus of the hydrogel film is 0.2-0.3MPa, the tensile breaking stress is 0.3-0.4MPa, and the tensile breaking elongation is 670-1180%.

B. Tear Strength Performance test

In this example, the tear strength performance of the preferred high strength self-healing hydrogel electrolyte prepared in example 1 was characterized:

(1) the poly (methacrylamide-co-acrylic acid) hydrogel was fished out of the potassium chloride electrolyte solution, the surface water was wiped off, a rectangular strip of 40mm in length and 6mm in width was cut out of the hydrogel film, then a cut of 30mm in length was made at one end of the sample from the middle, and the hydrogel sample was made into a pant-type tensile test piece, the thickness of which was measured with a vernier caliper.

(2) And (3) respectively clamping two trouser legs of the sample by using a clamp of a LEGEND 2345 tensile testing machine, setting the tensile speed to be 100mm/min, and gradually increasing the tensile force in the tensile process until the tensile force tends to be gentle to obtain stable force.

(3) And calculating the tearing energy of the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte according to a tearing strength formula.

The test shows that the tearing energy of the hydrogel electrolyte is 640-750J/m²。

C. Conductivity test

This example tests the conductivity of poly (methacrylamide-co-acrylic acid) hydrogel electrolytes by electrochemical impedance spectroscopy:

(1) two 10mm x 10mm copper sheets were prepared as current collectors, and the hydrogel electrolyte film was sandwiched between the two copper sheets.

(2) Obtaining an electrochemical impedance spectrum of the hydrogel electrolyte through an electrochemical workstation test, wherein impedance test parameters of the hydrogel electrolyte are as follows: the alternating current frequency is 100kHz-0.01Hz, and the amplitude is 5 mV.

(3) And obtaining the resistance according to the electrochemical impedance spectrum, and further obtaining the conductivity.

(4) To investigate the change in conductivity of the hydrogel electrolyte during stretching. The hydrogel electrolyte was clamped to the jaws of a vernier caliper with two clamps, stretched to 50%, 100%, 150%, and 200% lengths, respectively, and then tested for conductivity according to the conductivity test method.

The hydrogel electrolyte has the conductivity of 1.9-2.8S/m.

D. Self-healing performance test

In this example, a poly (methacrylamide-co-acrylic acid) physically crosslinked hydrogel is crosslinked using dynamic noncovalent bonds (hydrogen bonds), and this physical crosslinking is reconfigurable and has self-healing properties. The self-healing performance of the high-strength self-healing hydrogel electrolyte is characterized as follows:

(1) the water on the surface of the hydrogel electrolyte film was wiped off, and a rectangular specimen having a length of 40mm and a width of 6mm was cut out from the hydrogel film.

(2) After cutting the hydrogel electrolyte sample strips with the length of 40mm and the width of 6mm, as shown in FIG. 6 (a); then, the cut ends were immediately bonded together as shown in FIG. 6(b), and left at room temperature for half an hour.

(3) The self-healing hydrogel electrolyte obtained in step (2) can be easily taken up, as shown in fig. 6(c), and the self-healing hydrogel electrolyte crosslinked through dynamic physical bond-hydrogen bond is proved to have self-healing property. During the use process, if the hydrogel electrolyte is damaged, the hydrogel electrolyte can be reconstructed, and the service life of the electrolyte is prolonged.

The test shows that the fractured hydrogel electrolyte can be self-healed at normal temperature.

Example 2

The poly (methacrylamide-co-acrylic acid) hydrogel electrolyte obtained by example 1 was cut to a size of 30mm × 18 mm. Covering a mask on the surface of the cut poly (methacrylamide-co-acrylic acid) hydrogel electrolyte, coating a layer of slurry on the surface of the mask by using graphene slurry to form an electrode, coating a layer of silver-silver chloride slurry on the surface of the mask as a current collector after the graphene is solidified, tearing off the mask, waiting for the silver-silver chloride slurry to be solidified at normal temperature to obtain the interdigital electrode shown in the figure 7, and then leading out two leads on the positive and negative electrodes of the electrode. And finally, attaching a layer of polyacrylate adhesive tape to the upper surface and the lower surface of the supercapacitor for packaging to obtain the flexible supercapacitor taking the hydrogel as the electrolyte as shown in figure 9.

Fig. 10 is a graph showing the bending experimental object of the obtained flexible supercapacitor, and fig. 11 is a graph showing the result of the flexible supercapacitor stretching from 0% to 100%. The flexible super capacitor prepared by the method has the advantages of excellent high strength, stretchability, flexibility and the like.

A. Performance testing of flexible supercapacitors

In this embodiment, the flexible supercapacitor prepared by the present invention is characterized by an electrochemical impedance method, a cyclic voltammetry method, and a constant current method:

cyclic voltammetry: and performing cyclic voltammetry on the assembled super capacitor on an electrochemical workstation, setting a voltage window to be 0V to 0.3V, and performing 4 to 10 cycles at each scanning rate at scanning rates of 0.01V/s, 0.02V/s, 0.05V/s and 0.1V/s respectively.

Constant current method: and carrying out constant current charge and discharge test on the super capacitor on an electrochemical workstation. The test current is 0.1mA/cm²、0.15mA/cm²、0.2mA/cm²、0.25mA/cm²And the charging and discharging are carried out for 6 times in a circulating mode under each current.

Electrochemical impedance method: obtaining an electrochemical impedance spectrum of the flexible supercapacitor through an electrochemical workstation test, wherein impedance test parameters of the hydrogel electrolyte are as follows: the alternating current frequency is 100kHz-0.01Hz, and the amplitude is 5 mV.

The prepared flexible super capacitor has excellent electrochemical performance, and the electrochemical performance of the flexible super capacitor is 0.1mA/cm²When the current density of (2) is applied, the maximum area capacitance is 2mF/cm²The energy density can reach 160 mu Wh/cm²The power density was 48000. mu.W/cm²。

In conclusion, the high-strength self-healing hydrogel electrolyte provided by the invention is simple in preparation method, environment-friendly and excellent in mechanical property, the tensile elongation at break can reach 1180%, and the tensile stress at break can reach 0.4 MPa; the self-healing performance is excellent, the tensile breaking elongation after self-healing can reach 840%, and the tensile breaking stress can reach 0.2 MPa; has excellent electrical performance, and the maximum conductivity of the conductive material can reach 2.8S/m. The flexible supercapacitor formed by assembling the poly (methacrylamide-co-acrylic acid) hydrogel electrolyte and the serpentine-structure graphene interdigital electrode can be stretched in any direction, has high mechanical strength, excellent self-healing performance and high specific capacitance value, and has wide application prospect in the field of stretchable, high-strength and self-healing high-performance energy storage devices.