Preparation method of in-situ electrode and electrolyte integrated hydrogel and application of in-situ electrode and electrolyte integrated hydrogel in supercapacitor

Abstract

The invention relates to a preparation method of in-situ electrode and electrolyte integrated hydrogel and application of the hydrogel to a supercapacitor, and the preparation method of the hydrogel comprises the following steps: uniformly mixing anionic and cationic monomers, a cross-linking agent and an initiator, initiating the monomers to polymerize through ultraviolet light, and then soaking in water for balancing to obtain flexible amphoteric polyelectrolyte hydrogel; preparing a mixed solution of protonic acid and aniline, immersing the obtained amphoteric polyelectrolyte hydrogel into the mixed solution, standing for 2-12 hours, preparing a mixed solution of protonic acid and an oxidizing agent, adding the mixed solution into the mixed solution, and placing in an environment of 0-10 DEG C for 8-20 hours, so that aniline is subjected to in-situ polymerization reaction, and a layer of polyaniline is grown and coated on the surface of the amphoteric polyelectrolyte hydrogel. The supercapacitor comprises the hydrogel electrolyte and a conductive polymer electrode. The obtained integrated hydrogel type flexible supercapacitor has good flexibility and conductivity, and can be applied to energy storage equipment for intelligent wearable electronic equipment.

Description

Technical Field

[0001] The present invention relates to the field of polymer materials, in particular to a method for preparing an in-situ electrode-electrolyte integrated hydrogel and its application in supercapacitors. Background Art

[0002] With the widespread adoption of smart wearable electronics such as smartwatches, activity trackers, and health monitors, energy storage devices are evolving towards smaller size, longer battery life, and greater flexibility. Flexible supercapacitors, with their fast charge and discharge speeds, high power density, and excellent cycling stability, are considered the most promising energy storage devices for wearable electronics. Conventional flexible supercapacitors are typically assembled using a flexible electrode-electrolyte-electrode "sandwich" structure. Flexible electrodes are typically fabricated by coating or incorporating electroactive materials onto flexible conductive substrates such as flexible metal films, carbon-based films (carbon cloth, carbon paper, etc.), or flexible non-conductive substrates such as cellulose paper, cotton, textiles, and polymer films. Flexible electrolytes can be prepared by incorporating conductive ions into porous polymers and gel polymers. The flexible electrode / electrolyte heterogeneous structure of conventional flexible supercapacitors increases interfacial resistance, making them susceptible to interfacial displacement and detachment under tensile, bending, and shear deformations, leading to electrochemical performance degradation.

[0003] In recent years, with the rapid development of hydrogel preparation technology, the application of hydrogel electrolytes in flexible supercapacitors has also garnered attention. Patent documents such as "A Method for Preparing Flexible Polyaniline-Based Conductive Composite Hydrogel Material (CN201710190477.4)" describe the preparation of a conductive polyaniline-doped hydrogel by in-situ polymerization of phytic acid and aniline in a polyvinyl alcohol aqueous solution. Using non-conductive PVA hydrogel as the electrolyte matrix suffers from poor conductivity. Patent documents such as "Polyaniline / Phytic Acid Conductive Hydrogel, Preparation Method, and Flexible Supercapacitor (CN201810258794.X)" describe depositing a metal current collector on a flexible substrate such as PET, PE, or PP, then electrochemically depositing polyaniline to form electrodes. Finally, a PVA / H2SO4 gel electrolyte is poured into the supercapacitor. Depositing the metal current collector on the non-conductive flexible substrate improves conductivity to a certain extent, but the preparation process is relatively cumbersome. Patent documents such as "A method for preparing a hydrogel-based supercapacitor (CN202310746971.X)" introduce a method for preparing an integrated hydrogel supercapacitor by directly extruding an electrode slurry and an electrolyte slurry through a co-extrusion method. The raw materials of the electrode slurry include a polymer, an active substance, a conductive agent, and a solvent. Patent documents such as "A low-temperature-resistant, flexible, and stretchable fully amphoteric polyelectrolyte hydrogel supercapacitor and its preparation method (CN202310479337.4)" introduce a fully hydrogel supercapacitor constructed from an amphoteric polyelectrolyte gel electrolyte doped with an electrolyte aqueous solution and an amphoteric polyelectrolyte gel electrode doped with a conductive material and an electrolyte aqueous solution. The hydrogel electrode is prepared by polymerization in the presence of a conductive material. The conductive material doping amount is small, and it is often difficult to obtain ideal electrochemical properties. Summary of the Invention

[0004] To address the technical shortcomings of conventional sandwich-structured flexible supercapacitors, such as increased interfacial resistance due to the electrode / electrolyte heterogeneous structure, interface displacement and detachment under stretching, bending, and shear deformation, and poor performance of non-conductive hydrogel electrolytes, this invention provides an in-situ electrode-electrolyte integrated hydrogel for supercapacitors and a method for preparing the same. Supercapacitors based on this hydrogel exhibit excellent ionic conductivity and flexibility.

[0005] The technical solutions of the present invention are as follows: A method for preparing an in-situ electrode-electrolyte integrated hydrogel comprises the following steps: (1) Anionic monomers, cationic monomers, crosslinking agents, and initiators are uniformly mixed, and the monomers are polymerized in a glass mold by UV light initiation and then soaked in water for equilibrium to obtain a flexible amphoteric polyelectrolyte hydrogel; (2) preparing a mixed solution of protonic acid and aniline, immersing the obtained amphoteric polyelectrolyte hydrogel in the mixed solution and allowing it to stand for 2 to 12 hours; (3) preparing a mixed solution of protonic acid and ammonium persulfate, adding the solution to the mixed solution in step (2), mixing evenly, and placing the resulting mixed solution in an environment of 0-10°C for 8-20 hours to allow aniline to undergo in situ polymerization, thereby growing and coating a layer of polyaniline (PANI) on the surface of the amphoteric polyelectrolyte hydrogel; (4) After the polymerization is completed, the mixture is washed with deionized water to remove the residual aniline monomer and ammonium persulfate, thereby obtaining the in-situ electrode-electrolyte integrated hydrogel.

[0006] Furthermore, the anionic monomer is sodium p-styrene sulfonate; The cationic monomer is 3-(methacrylamide)propyltrimethylammonium chloride; The molar ratio of the anionic monomer to the cationic monomer is 1:0.9 to 1.1, for example, 1:0.95, 1:1, or 1:1.05; The molar amount of the cross-linking agent accounts for 0.05-0.15 mol% of the total amount of the anionic and cationic monomers, for example, 0.08 mol%, 0.1 mol%, 0.12 mol%; The molar amount of the initiator is 0.2-0.3 mol % of the total molar amount of the monomers, for example, 0.21 mol %, 0.22 mol %, 0.23 mol %, 0.24 mol %, 0.25 mol %, 0.26 mol %, 0.27 mol %, 0.28 mol %, and 0.29 mol %.

[0007] Furthermore, the total concentration of the cationic monomer and the anionic monomer is 2.0-2.5 mol / L, for example, 2.1 mol / L, 2.2 mol / L, 2.3 mol / L, or 2.4 mol / L.

[0008] Furthermore, the water equilibration in step (1) refers to the amphoteric polyelectrolyte hydrogel being immersed in water to reach swelling equilibrium for a time period of not less than 12 hours, such as 24 hours or 48 hours.

[0009] Furthermore, during the soaking and balancing process in step (1), the amount of water used for soaking is more than 20 times the weight of the hydrogel itself.

[0010] Furthermore, during the soaking water balancing process in step (1), the soaking water is replaced at least once.

[0011] Furthermore, the cross-linking agent is selected from one or more of the group consisting of condensation product of ethyl isocyanate acrylate and ethylene glycol BAGU, ethylene glycol dimethacrylate EGDMA, triallyl isocyanurate TAIC, and polyethylene glycol diacrylate PEGDA.

[0012] Furthermore, the BAGU can be a commercial product or homemade. The homemade method is as follows: Under a protective atmosphere, such as nitrogen, ethyl isocyanate acrylate (INA) is added dropwise to ethylene glycol (EG), the reaction temperature is controlled not to exceed 5°C, and the reaction is stirred for 8 to 24 hours, so that the isocyanate group (-NCO) in INA and the hydroxyl group (-OH) in EG undergo an addition reaction to obtain the crosslinker BAGU.

[0013] Furthermore, in the above preparation process, the molar ratio of INA to EG is 2:1, and the reaction formula is as follows: .

[0014] Furthermore, the photoinitiator is selected from one or both of 2-ketoglutaric acid KA and Irgacure 2959.

[0015] Furthermore, the ultraviolet wavelength used in the ultraviolet irradiation is 365 nm, and the irradiation time is 8 to 12 h.

[0016] Furthermore, the proton acid is phytic acid, and the concentration of the proton acid in the mixed solution of step (2) and step (3) is 0.3-0.7 mol / L, for example, 0.4 mol / L, 0.5 mol / L, or 0.6 mol / L.

[0017] Furthermore, the temperature of the in-situ polymerization reaction in step (3) is 2-8°C, for example, 2°C, 3°C, 4°C, 5°C, 6°C, or 7°C.

[0018] Furthermore, during the in-situ polymerization reaction in step (3), as the polymerization time increases, the surface polyaniline grows thicker, but a thicker thickness may lead to a decrease in mechanical properties. The in-situ polymerization reaction time is 8 to 20 hours, more preferably 10 to 18 hours, for example 12 hours, 14 hours, or 16 hours.

[0019] Furthermore, the ammonium persulfate acts as an oxidant, providing free radicals or positive ions that promote the dehydrogenation of the aniline monomer to form cationic free radicals, which then propagate the chain to form a polymer. The ammonium persulfate can be used in a molar ratio of 1:(1-5), such as 1:2, 1:3, or 1:4.

[0020] The present invention also provides an in-situ electrode-electrolyte integrated hydrogel, which is prepared by the above method.

[0021] The present invention also provides the use of the above-mentioned in-situ electrode electrolyte integrated hydrogel in a supercapacitor. After cutting the edges of the in-situ electrode electrolyte integrated hydrogel, current collectors are attached to both sides and packaged to obtain an integrated hydrogel-type flexible supercapacitor.

[0022] Furthermore, the supercapacitor after in-situ polymerization is trimmed to avoid short circuit, a piece of carbon fiber cloth is added to each side as a current collector, and encapsulated with polyester film and tape to obtain an integrated hydrogel-type flexible supercapacitor.

[0023] Furthermore, the supercapacitor is used to prepare an energy storage device for smart wearable electronic devices.

[0024] The present invention also provides a supercapacitor, which includes a packaging material, a current collector located in the packaging material, and an electrode-electrolyte integrated hydrogel, and the electrode-electrolyte integrated hydrogel is prepared by the above method.

[0025] The present invention uses amphoteric polyelectrolyte (PA) hydrogel as the matrix part of the flexible supercapacitor electrolyte. Compared with non-electrolyte hydrogels, PA hydrogel network molecules have abundant anions and cations. First, they can form interchain electrostatic interactions. The covalent cross-linked structure formed by the cross-linker can synergistically improve the mechanical properties of the hydrogel, making the gel network less susceptible to damage when subjected to external stress stimulation, and also making the assembled supercapacitor flexible and deformable. Second, the anions and cations on the PA hydrogel network molecules give the hydrogel electrolyte good hydrophilicity, turning the free water between the chains into bound water, constructing ion transmission channels, and a large number of counterions (such as H + ) can improve its conductivity. By introducing phytic acid into the PA hydrogel and PANI electrode, the small molecule electrolyte phytic acid ionizes and dissociates to release negatively charged phosphate groups, which combine with the cations in the PA hydrogel macromolecular units, promoting the phase separation of anionic / cationic polyelectrolytes in the PA hydrogel. PANI has strong aromaticity, and phase separation enhances the "cation-π" interaction between the cationic polyelectrolyte and PANI in the PA hydrogel. At the same time, the phytic acid functional groups can also form hydrogen bonds with groups such as -NH- and -C=O in the PA hydrogel molecules, synergistically improving the mechanical properties of the integrated hydrogel-type flexible supercapacitor while also constructing hydrophilic ion transmission channels, significantly improving ionic conductivity. Therefore, in the PANI electrode, phytic acid can not only form ionic electrostatic interactions and hydrogen bonds with PANI molecules to improve the mechanical properties of PANI, but also, as an acid dopant, it can enhance the conductive properties of polyaniline through protonation.

[0026] The present invention has the following advantages and beneficial effects: 1. The present invention is based on an integrated structural design. The polyaniline electrode is generated by in-situ polymerization on the surface of an amphoteric polyelectrolyte hydrogel electrolyte. The polyaniline molecules are embedded on the surface or near the surface of the hydrogel electrolyte, which not only reduces the interfacial contact resistance but also prevents the supercapacitor from interfacial displacement and detachment under stretching, bending and shear deformation.

[0027] 2. The present invention uses amphoteric polyelectrolyte hydrogel as a flexible electrolyte matrix. The positive and negative ion groups contained in the polymer chain construct an efficient ion transmission channel. It is rich in bound water and hydrogen ions, giving it good conductive properties. In addition, the formed ionic electrostatic binding network structure and the cross-linking agent form a covalent cross-linking structure during copolymerization, which synergistically gives it good mechanical properties.

[0028] 3. The present invention incorporates phytic acid, which not only forms hydrogen bonds and ionic interactions with the -NH- and protonated groups of the polyaniline molecule in the polyaniline electrode to act as a crosslinker, but also acts as an acid dopant to improve the conductive properties of the polyaniline through protonation, and also plays a role in crosslinking and improving the conductivity in the amphoteric polyelectrolyte hydrogel electrolyte.

[0029] 4. The integrated hydrogel supercapacitor prepared by the present invention has excellent flexibility and excellent electrochemical performance. The area specific capacitance of the obtained supercapacitor can reach 883 mF / cm at a scan rate of 1 mV / s. 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the preparation process of the amphoteric polyelectrolyte hydrogel PA of this application; Figure 2 Schematic diagram of the preparation process of the integrated hydrogel-type flexible supercapacitor of this application and the intermolecular interaction of the in-situ electrode-electrolyte integrated hydrogel; Figure 3 The area capacitance of the supercapacitors obtained in the examples and comparative examples of this application at different scan rates is shown in Figure 2. ... 2 ; Figure 4 This is a physical picture of the application of the supercapacitor series device obtained in this application. DETAILED DESCRIPTION

[0031] For a better understanding of the present invention, the following examples are provided to further illustrate the present invention, but the present invention is not limited to the following examples.

[0032] The cross-linking agent BAGU used in the embodiment of the present invention is homemade, and the preparation method is as follows: Under nitrogen protection, 5 g (0.035 mol) of ethyl isocyanate acrylate (INA) was slowly added dropwise to a 25 mL three-necked flask containing 1.055 g (0.017 mol) of ethylene glycol (EG). The mixture was stirred in an ice-water bath (0°C) for 12 hrs to allow the isocyanate group (-NCO) to react with the hydroxyl group (-OH) to obtain the crosslinker BAGU, which was stored in the refrigerator until use.

[0033] Example 1 (1) Weigh 2.58 g of sodium p-styrenesulfonate (hereinafter referred to as NaSS), 2.76 g of 3-(methacrylamide)propyltrimethylammonium chloride (hereinafter referred to as MPTC), 0.0037 g of BAGU, and 0.0091 g of photoinitiator α-ketoglutaric acid (hereinafter referred to as KA), add 10 mL of deionized water (total monomer concentration is 2.5 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 ° C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water for equilibrium to obtain P(NaSS- co -MPTC) amphoteric polyelectrolyte (hereinafter referred to as PA) hydrogel.

[0034] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of phytic acid and aniline (phytic acid concentration was 0.5 M, aniline (hereinafter referred to as ANI) concentration was 1.0 M) for 3 hours, and then 20 mL of a mixed solution of phytic acid and ammonium persulfate (hereinafter referred to as APS) (phytic acid concentration was 0.5 M, APS concentration was 1.0 M) was added and shaken for 3-5 minutes to mix them evenly. The above solution was then placed in a refrigerator at 5°C for 12 hours to react. A layer of polyaniline (PANI) was grown and coated on the surface of the PA hydrogel membrane by in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. It was then cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and a polyester (PET) film and tape were used to encapsulate the flexible supercapacitor (hereinafter referred to as FSC).

[0035] Example 2 (1) Weigh 2.37 g NaSS, 2.54 g MPTC, 0.0036 g BAGU, and 0.0081 g KA, add 10 mL deionized water (total monomer concentration is 2.3 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0036] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of 20 mL of phytic acid and ANI (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.5 M) was added and shaken for 3-5 minutes to mix evenly. The above solution was then placed in a refrigerator at 5°C for 12 hours to react. A layer of PANI was grown and coated on the surface of the PA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. It was then cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0037] Example 3 (1) Weigh 2.06 g NaSS, 2.21 g MPTC, 0.0031 g BAGU, and 0.0073 g KA, add 10 mL deionized water (total monomer concentration is 2.0 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0038] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of 20 mL of phytic acid and ANI (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.33 M) was added and shaken for 3-5 minutes to mix evenly. The above solution was then placed in a refrigerator at 5°C for 12 hours to react. A layer of PANI was grown and coated on the surface of the PA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. It was then cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0039] Example 4 (1) Weigh 2.37 g NaSS, 2.54 g MPTC, 0.0036 g BAGU, and 0.0081 g KA, add 10 mL deionized water (total monomer concentration is 2.3 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0040] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of 20 mL of phytic acid and ANI (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.2 M) was added and shaken for 3-5 minutes to mix evenly. The above solution was then placed in a refrigerator at 5°C for 12 hours to react. A layer of PANI was grown and coated on the surface of the PA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. The membrane was cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0041] Example 5 (1) Weigh 2.37 g NaSS, 2.54 g MPTC, 0.0036 g BAGU, and 0.0081 g KA, add 10 mL deionized water (total monomer concentration is 2.3 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0042] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of 20 mL of phytic acid and ANI (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.5 M) was added and shaken for 3-5 minutes to mix evenly. The above solution was then placed in a refrigerator at 5°C for 8 hours to react. A layer of PANI was grown and coated on the surface of the PA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. The membrane was cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0043] Example 6 (1) Weigh 2.37 g NaSS, 2.54 g MPTC, 0.0036 g BAGU, and 0.0081 g KA, add 10 mL deionized water (total monomer concentration is 2.3 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0044] (2) The PA hydrogel membrane after soaking in water was immersed in a mixed solution of 20 mL of phytic acid and ANI (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.5 M) was added and shaken for 3-5 minutes to mix them evenly. The above solution was then placed in a refrigerator at 5°C for 20 hours to react. A layer of PANI was grown and coated on the surface of the PA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. It was then cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0045] Comparative Example 1 (1) Weigh 2 g of polyvinyl alcohol (PVA) at room temperature and add 10 ml of deionized water to prepare a mixed solution; mix and stir in a 90°C water bath until the PVA is completely dissolved, then inject it into a glass mold, place it at -4°C, freeze it for 8 hours, and then thaw it at room temperature for 8 hours. Repeat the freeze-thaw cycle 3 times to obtain the PVA hydrogel.

[0046] (2) The PVA hydrogel film was immersed in a 20 mL mixed solution of phytic acid and aniline (phytic acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phytic acid and APS (phytic acid concentration was 0.5 M, APS concentration was 0.5 M) was added and shaken for 3-5 minutes to mix them evenly. The above solution was then placed in a 5°C refrigerator to react for 12 hours. A layer of PANI was grown and coated on the surface of the PVA hydrogel film by in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. It was then cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape. The molar ratio of APS to ANI was 1:2.

[0047] Comparative Example 2 (1) Weigh 2.37 g NaSS, 2.54 g MPTC, 0.0036 g BAGU, and 0.0081 g KA, add 10 mL deionized water (total monomer concentration is 2.3 mol / L, the molar ratio of BAGU to the total monomer is 0.10 mol%, and the molar ratio of KA to the total monomer is 0.25 mol%), stir in a 65 °C hot water bath for 10 min to mix evenly, then inject it into a glass mold and react under ultraviolet light for 10 hrs; after the reaction is completed, demould and the polymer product is soaked in water to equilibrate to obtain PA hydrogel.

[0048] (2) The PA hydrogel membrane was immersed in a mixed solution of 20 mL of phosphoric acid and ANI (phosphoric acid concentration was 0.5 M, ANI concentration was 1.0 M). After soaking for 3 hours, 20 mL of a mixed solution of phosphoric acid and APS (phosphoric acid concentration was 0.5 M, APS concentration was 0.5 M) was added and shaken for 3-5 minutes to mix evenly. The above solution was then placed in a refrigerator at 5°C for 12 hours to react. A layer of PANI was grown on the surface of the PVA hydrogel membrane through in situ polymerization. After the polymerization was completed, it was washed several times with deionized water to remove the residual aniline monomer and APS. The membrane was cut and trimmed to obtain an integrated hydrogel supercapacitor. Finally, a piece of carbon fiber cloth was added to each side as a current collector, and the FSC was encapsulated with PET film and tape.

[0049] Table 1 Mechanical and electrical properties of supercapacitors at different temperatures

[0050] Note: The area capacitance was measured at a scan rate of 1 mV / s.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an in-situ electrode-electrolyte integrated hydrogel, characterized in that: The steps include: (1) Anionic monomers, cationic monomers, crosslinking agents, and initiators are uniformly mixed, and the monomers are polymerized in a glass mold by UV light initiation and then soaked in water for equilibrium to obtain a flexible amphoteric polyelectrolyte hydrogel; (2) preparing a mixed solution of protonic acid and aniline, immersing the obtained amphoteric polyelectrolyte hydrogel in the mixed solution and allowing it to stand for 2 to 12 hours; (3) preparing a mixed solution of protonic acid and ammonium persulfate, adding the solution to the mixed solution in step (2), mixing evenly, and placing the resulting mixed solution in an environment of 0-10°C for 8-20 hours to allow aniline to undergo in situ polymerization, thereby growing and coating a layer of polyaniline on the surface of the amphoteric polyelectrolyte hydrogel; (4) After the polymerization is completed, the mixture is washed with deionized water to remove the residual aniline monomer and ammonium persulfate, thereby obtaining the in-situ electrode-electrolyte integrated hydrogel.

2. The method for preparing the in-situ electrode-electrolyte integrated hydrogel according to claim 1, characterized in that: The anionic monomer is sodium p-styrene sulfonate; The cationic monomer is 3-(methacrylamide)propyltrimethylammonium chloride; The molar ratio of the anionic monomer to the cationic monomer is 1:0.9-1.1; The total concentration of the cationic monomer and the anionic monomer is 2.0-2.5 mol / L; The molar amount of the cross-linking agent accounts for 0.05-0.15 mol% of the total amount of the anionic and cationic monomers; The molar amount of the initiator is 0.2-0.3 mol % of the total molar amount of the monomers.

3. The method for preparing the in-situ electrode-electrolyte integrated hydrogel according to claim 1, characterized in that: The soaking time in step (1) is no less than 12 hours.

4. The method for preparing the in-situ electrode-electrolyte integrated hydrogel according to claim 1, characterized in that: The cross-linking agent is selected from one or more of the condensation product of ethyl isocyanate acrylate and ethylene glycol BAGU, ethylene glycol dimethacrylate EGDMA, triallyl isocyanurate TAIC, and polyethylene glycol diacrylate PEGDA; The photoinitiator is selected from one or both of 2-ketoglutaric acid KA and Irgacure 2959.

5. The method for preparing the in-situ electrode-electrolyte integrated hydrogel according to claim 1, wherein: The proton acid is phytic acid, and the concentration of the proton acid in the mixed solution of step (2) and step (3) is 0.3-0.7 mol / L.

6. The method for preparing the in-situ electrode-electrolyte integrated hydrogel according to claim 1, characterized in that: The molar ratio of the ammonium persulfate to the aniline is 1:(1-5).

7. An in-situ electrode-electrolyte integrated hydrogel, characterized in that: The method according to any one of claims 1 to 6 is used for preparation.

8. Application of in-situ electrode-electrolyte integrated hydrogel in supercapacitors, characterized by: The in-situ electrode-electrolyte integrated hydrogel is prepared by the method according to any one of claims 1 to 6; The in-situ electrode-electrolyte integrated hydrogel is cut and trimmed, current collectors are attached to both sides, and the gel is packaged to obtain an integrated hydrogel-type flexible supercapacitor.

9. The use according to claim 8, characterized in that The supercapacitor is used to prepare an energy storage device for smart wearable electronic devices.

10. A supercapacitor, characterized in that: The supercapacitor comprises a packaging material, a current collector located in the packaging material, and an electrode-electrolyte integrated hydrogel, wherein the electrode-electrolyte integrated hydrogel is prepared by the method according to any one of claims 1 to 6.

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