Self-healing hydrogel supercapacitor and preparation method and application thereof

Abstract

The invention belongs to the field of flexible wearable energy storage, and discloses a self-healing hydrogel supercapacitor and a preparation method and application thereof. The preparation method comprises the following steps: dropwise adding a tannic acid aqueous solution into a PVA and sodium alginate aqueous solution, carrying out crosslinking on PVA and tannic acid through hydrogen-bond interaction under heating and stirring, carrying out crosslinking on sodium alginate and calcium ions to form a hydrogel electrolyte, mixing the PVA aqueous solution with a conductive polymer PEDOT: PSS aqueous solution under stirring, and carrying out stirring to obtain the conductive polymer PEDOT: PSS hydrogel electrolyte. And dropwise adding a tannic acid aqueous solution to carry out crosslinking and rapid fixation to obtain the PVA / tannic acid and conductive polymer PEDOT: PSS hydrogel electrode. The hydrogel electrolyte and the hydrogel electrode are combined and assembled to form the self-healing full-hydrogel supercapacitor with a sandwich structure. The self-healing hydrogel supercapacitor prepared by the invention has a good application prospect in the field of flexible and portable electronic equipment.

Description

Technical Field

[0001] The present invention belongs to the field of flexible wearable energy storage, and in particular relates to a self-healing hydrogel supercapacitor and a preparation method and application thereof. Background Art

[0002] Due to the popularity of portable and flexible wearable electronic devices, electronic products that are stretchable, self-healing, flexible, smart and wearable, including electronic sensors, flexible displays and electronic skin, have attracted widespread attention. In order to better meet the energy needs of the above-mentioned electronic products, the development of flexible energy storage devices that match them has become a bottleneck for the sustainable development of flexible electronic devices. Self-healing flexible supercapacitors mainly use electrolytes or electrode materials with self-healing properties to achieve self-healing effects. When the material is damaged, the self-healing material can release healing agents or combine with the intrinsic reversible chemical bonds of the material to automatically repair and restore the mechanical and electrochemical properties of the supercapacitor. Therefore, it is expected to extend the service life of flexible wearable electronic devices, save economic costs, and improve the overall safety of the device.

[0003] In recent years, hydrogel systems have been continuously enriched and their performance has been continuously optimized. Their outstanding hydrophilicity, light transmittance, elasticity and self-healing properties are all very important properties for functional energy storage devices. More importantly, the rich polymer chemistry and engineering technology give hydrogel materials great design capabilities and adjustability. Hydrogels with oriented structures have broad application prospects in the fields of materials, biomedicine, and flexible devices. The unique three-dimensional network structure and water-containing state of hydrogels provide channels for ion transport and have good application prospects. After functional modification, some dynamic network hydrogels also have high elasticity and self-healing properties. These properties are crucial for energy storage devices and are expected to promote the development of wearable electronic devices.

[0004] At present, there are some literature reports and a few patents that apply hydrogels to supercapacitors. For example, Chinese patent CN117079983A discloses a method for preparing an integrated hydrogel-based supercapacitor; CN116825550A discloses a method for preparing a low-temperature-resistant, flexible and stretchable all-polyampholyte hydrogel supercapacitor; CN117292950A discloses a method for preparing a zwitterionic hydrogel electrolyte and its application in zinc ion hybrid capacitors, etc. There is only one patent report on self-healing supercapacitors. For example, in Chinese invention patent publication number CN201710566991.3, the prepared manganese dioxide-loaded carbon nanotubes are dripped on the substrate to form a conductive film with a conductive network structure; polycaprolactone and elastic polyurethane are mixed and stirred to be uniformly dispersed in an organic solvent and dripped on the conductive film, which is cured by heating to form a conductive film; one side of the carbon nanotubes loaded with manganese dioxide is coated with a gel electrolyte to form a composite electrode, and two composite electrodes are assembled to obtain a supercapacitor with self-healing properties. Although the above-mentioned elastomers can achieve the function of self-healing, the synthesis method and operation steps are relatively complicated, and the operation process is cumbersome. As for the use of self-healing stretchable hydrogels in flexible devices, no relevant reports were found through patent inquiries. In addition, there are few reports on the application of electrode performance of self-healing hydrogel supercapacitors, and further in-depth exploration is necessary. Therefore, it is still necessary to continue to develop self-healing materials for flexible supercapacitor electrodes and electrolytes, rationally design self-healing material components, and through functional modification, enable the self-healing materials induced by electrical stimulation to achieve in-situ self-healing during the charging and discharging process. Achieving high-efficiency self-healing of flexible supercapacitor devices as a whole is an important direction for future development. Summary of the invention

[0005] In order to overcome the shortcomings and deficiencies of the above-mentioned prior art, the primary purpose of the present invention is to provide a method for preparing a self-healing hydrogel supercapacitor; the method selects polyvinyl alcohol (PVA) and tannic acid (TA) as the main materials of the gel to form a hydrogel electrolyte, and sodium alginate and calcium ions are also added thereto, PVA and tannic acid are cross-linked by hydrogen bonds, and the hydrogen bond cross-linking has better self-healing properties; while sodium alginate and calcium ions are cross-linked by ionic action, which can improve the mechanical properties and ion transfer rate of the gel; in addition, the conductive polymer PEDOT:PSS is doped in the self-healing hydrogel electrode body (PVA and tannic acid), and acid-doped at the same time, so that the gel produces a double-cross-linked network, thereby achieving simultaneous enhancement of mechanical strength and self-healing efficiency, providing an experimental basis and theoretical basis for the development of flexible devices.

[0006] Another object of the present invention is to provide a self-healing hydrogel supercapacitor prepared by the above preparation method.

[0007] Another object of the present invention is to provide an application of the self-healing hydrogel supercapacitor.

[0008] The purpose of the present invention is achieved through the following solutions:

[0009] A method for preparing a self-healing hydrogel supercapacitor comprises the following steps:

[0010] (1) stirring and mixing a PVA aqueous solution and a sodium alginate solution to obtain a mixed solution, then dripping a tannic acid aqueous solution into the mixed solution drop by drop, and finally adding a calcium ion solution, stirring and reacting at a temperature of 70-100° C. for 1-5 hours, wherein PVA and tannic acid are cross-linked through hydrogen bonding, and sodium alginate and calcium ions are cross-linked through coordination, and finally a hydrogel electrolyte PVA-SA / TA-Ca is formed;

[0011] (2) mixing a PVA aqueous solution and an aqueous solution of a conductive polymer PEDOT:PSS under stirring to obtain a mixed solution, and then dripping a tannic acid aqueous solution into the mixed solution dropwise for crosslinking and fixation to obtain a hydrogel electrode PVA / TA-PEDOT of PVA / tannic acid and conductive polymer PEDOT:PSS;

[0012] (3) Cutting one sheet of the hydrogel electrolyte obtained in step (1) and two sheets of the hydrogel electrodes obtained in step (2) into the same size, and then stacking and assembling them to form a sandwich integrated hydrogel supercapacitor, that is, a self-healing hydrogel supercapacitor.

[0013] The concentration of the PVA aqueous solution in step (1) is 10 mg / mL-20 mg / mL; the concentration of the tannic acid aqueous solution is 15-25 mg / mL; the concentration of the sodium alginate solution is 10-30 mg / mL; the concentration of the calcium ion solution is 5 mg / mL-10 mg / mL; the volume ratio of the PVA aqueous solution to the tannic acid aqueous solution is 1:1; the volume ratio of the PVA aqueous solution to the sodium alginate solution is 2:1, and the volume ratio of the sodium alginate solution to the calcium ion solution is 1:1.

[0014] The stirring reaction in step (1) is carried out at 80° C. for 2 hours;

[0015] The models of the conductive polymer PEDOT:PSS described in step (2) are Clevios PH 1000, Clevios PH500, and 4083, and the best model is Clevios PH 1000.

[0016] The concentration of the PVA aqueous solution in step (2) is 10 mg / mL-20 mg / mL; the concentration of the conductive polymer PEDOT:PSS aqueous solution is 10-20 mg / mL; the concentration of the tannic acid aqueous solution is 15-25 mg / mL; the volume ratio of the PVA aqueous solution, the conductive polymer PEDOT:PSS aqueous solution and the tannic acid aqueous solution is 1:2:1.

[0017] A self-healing hydrogel supercapacitor prepared by the above preparation method uses the self-healing conductive hydrogel as an electrode and the self-healing hydrogel as an electrolyte.

[0018] The above-mentioned self-healing hydrogel supercapacitor is used in the field of flexible and portable electronic devices.

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

[0020] (1) The self-healing hydrogel prepared by the present invention can self-heal in a short time. The hydrogel can be used as an electrode material for supercapacitors to obtain better electrochemical performance.

[0021] (2) The method of the present invention is simple, low-cost and has good industrial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the preparation process of self-healing hydrogel electrolyte and hydrogel electrode and their assembly into supercapacitor;

[0023] Figure 2 Optical images of the hydrogel electrolyte (left) and hydrogel electrode (right) in Micro Example 1;

[0024] Figure 3 This is a stretching picture of the hydrogel electrolyte in Example 1;

[0025] Figure 4 Pictures of the compression properties of the hydrogel electrolyte and hydrogel electrode in Example 1 tested by a micro-universal electronic tensile machine. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below in conjunction with the examples and drawings, but the embodiments of the present invention are not limited thereto. If specific conditions are not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] Unless otherwise specified, the reagents used in the examples can be purchased from the market.

[0028] Example 1

[0029] A method for preparing a self-healing hydrogel supercapacitor comprises the following steps:

[0030] (1) A 10 mg / mL PVA aqueous solution and a 10 mg / mL sodium alginate solution are stirred and mixed to obtain a mixed solution, and a 10 mg / mL tannic acid aqueous solution is added dropwise into the mixed solution, and finally a 10 mg / mL calcium ion solution is added, and the mixture is stirred and reacted at 80° C. for 2 hours, wherein the PVA and tannic acid (TA) are cross-linked through hydrogen bonding, and the sodium alginate and the calcium ions are cross-linked through coordination to form a hydrogel electrolyte (PVA-SA / TA-Ca), wherein the volume ratio of the PVA aqueous solution to the tannic acid aqueous solution is 1:1, the volume ratio of the PVA aqueous solution to the sodium alginate solution is 2:1, and the volume ratio of the sodium alginate solution to the calcium ion solution is 1:1.

[0031] (2) A 20 mg / mL PVA aqueous solution and a 10 mg / mL conductive polymer PEDOT:PSS aqueous solution were mixed under stirring to obtain a mixed solution, and then a 20 mg / mL tannic acid aqueous solution was dripped into the mixed solution for cross-linking and fixation to obtain a PVA / tannic acid and conductive polymer PEDOT:PSS hydrogel electrode (PVA / TA-PEDOT), wherein the volume ratio of the PVA aqueous solution, the conductive polymer PEDOT:PSS aqueous solution and the tannic acid aqueous solution was 1:2:1.

[0032] (3) Cutting one sheet of the hydrogel electrolyte obtained in step (1) and two sheets of the hydrogel electrodes obtained in step (2) into the same size, and then stacking and assembling them to form a sandwich integrated hydrogel supercapacitor, i.e., a self-healing hydrogel supercapacitor, and then testing various electrochemical properties of the supercapacitor.

[0033] The preparation process of the self-healing hydrogel electrolyte and the hydrogel electrode in Example 1 of the present invention and the process of assembling them into a supercapacitor are as follows: Figure 1 shown.

[0034] The hydrogel electrolyte and hydrogel electrode prepared in Example 1 of the present invention are as follows Figure 2 As shown, the hydrogel electrolyte is colorless and transparent; the hydrogel electrode is blue-black.

[0035] The hydrogel electrolyte prepared in Example 1 of the present invention has good tensile properties, such as Figure 3 shown.

[0036] The hydrogel electrolyte and electrode prepared in Example 1 of the present invention have good compression properties. Figure 4 shown.

[0037] Comparative Example 1

[0038] The preparation of PVA / tannic acid hydrogel electrolyte specifically includes the following steps:

[0039] A 0.2 mol / L tannic acid aqueous solution was added dropwise into a 20 mg / mL PVA aqueous solution, wherein the volume ratio of the PVA aqueous solution to the tannic acid aqueous solution was 1:1. Under stirring, the two were cross-linked through hydrogen bonding to form a hydrogel electrolyte (PVA / TA).

[0040] Among them, PVA and tannic acid are only cross-linked by hydrogen bonds. Although they have certain self-healing functions, the mechanical properties of the hydrogel formed by hydrogen bond cross-linking are worse than those of the hydrogel double cross-linked by hydrogen bonds and ionic bonds in the embodiment.

[0041] Comparative Example 2

[0042] The preparation of sodium alginate / calcium ion hydrogel electrolyte specifically includes the following steps:

[0043] A 0.2 mol / L calcium chloride aqueous solution was added dropwise into a 20 mg / mL sodium alginate aqueous solution, wherein the volume ratio of the sodium alginate solution to the calcium ion solution was 1:1, and the two were cross-linked through ion complexation under stirring to form a hydrogel electrolyte (PVA / TA).

[0044] Among them, sodium alginate and calcium ions form gel through ionic cross-linking, and the obtained hydrogel electrolyte has no self-healing function, which is contrary to the subject of the present invention.

[0045] Comparative Example 3

[0046] Preparation of hydrogel electrodes formed by sodium alginate / calcium ions and conductive polymer PEDOT:PSS:

[0047] A sodium alginate aqueous solution with a concentration of 20 mg / mL and a conductive polymer PEDOT:PSS aqueous solution with a concentration of 10 mg / mL are mixed under stirring, and then a 0.2 mol / L calcium chloride aqueous solution is dropwise added to the mixed solution for cross-linking and rapid fixation to obtain a sodium alginate / calcium ion-conductive polymer PEDOT:PSS hydrogel (SA / Ca-PEDOT); the volume ratio of the sodium alginate aqueous solution, the conductive polymer PEDOT:PSS aqueous solution and the calcium chloride aqueous solution is 1:2:1.

[0048] Similar to Comparative Example 2, sodium alginate and calcium ions are gelled through ionic crosslinking, and the resulting hydrogel has no self-healing function. Even if a conductive polymer is added, the final hydrogel can conduct electricity but has no self-healing function, which is contrary to the subject of the present invention.

[0049] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing a self-healing hydrogel supercapacitor, characterized in that The following steps are involved: (1) stirring and mixing a PVA aqueous solution and a sodium alginate solution to obtain a mixed solution, then dripping a tannic acid aqueous solution into the mixed solution drop by drop, and finally adding a calcium ion solution, stirring and reacting at a temperature of 70-100° C. for 1-5 hours, wherein PVA and tannic acid are cross-linked through hydrogen bonding, and sodium alginate and calcium ions are cross-linked through coordination, and finally a hydrogel electrolyte PVA-SA / TA-Ca is formed; (2) mixing a PVA aqueous solution and an aqueous solution of a conductive polymer PEDOT:PSS under stirring to obtain a mixed solution, and then dripping a tannic acid aqueous solution into the mixed solution dropwise for crosslinking and fixation to obtain a hydrogel electrode PVA / TA-PEDOT of PVA / tannic acid and conductive polymer PEDOT:PSS; (3) Cutting one sheet of the hydrogel electrolyte obtained in step (1) and two sheets of the hydrogel electrodes obtained in step (2) into the same size, and then stacking and assembling them to form a sandwich integrated hydrogel supercapacitor, that is, a self-healing hydrogel supercapacitor.

2. The method for preparing a self-healing hydrogel supercapacitor according to claim 1, characterized in that: The concentration of the PVA aqueous solution in step (1) is 10 mg / mL-20 mg / mL; the concentration of the tannic acid aqueous solution is 15-25 mg / mL; the concentration of the sodium alginate solution is 10-30 mg / mL; the concentration of the calcium ion solution is 5 mg / mL-10 mg / mL; the volume ratio of the PVA aqueous solution to the tannic acid aqueous solution is 1:1; the volume ratio of the PVA aqueous solution to the sodium alginate solution is 2:1, and the volume ratio of the sodium alginate solution to the calcium ion solution is 1:

1.

3. The method for preparing a self-healing hydrogel supercapacitor according to claim 1, characterized in that: The stirring reaction in step (1) is carried out at 80° C. for 2 hours.

4. The method for preparing a self-healing hydrogel supercapacitor according to claim 1, characterized in that: The model of the conductive polymer PEDOT:PSS described in step (2) is Clevios PH 1000, Clevios PH 500 or 4083.

5. The method for preparing a self-healing hydrogel supercapacitor according to claim 1, characterized in that: The model of the conductive polymer PEDOT:PSS described in step (2) is Clevios PH 1000.

6. The method for preparing a self-healing hydrogel supercapacitor according to claim 1, characterized in that: The concentration of the PVA aqueous solution in step (2) is 10 mg / mL-20 mg / mL; the concentration of the conductive polymer PEDOT:PSS aqueous solution is 10-20 mg / mL; the concentration of the tannic acid aqueous solution is 15-25 mg / mL; the volume ratio of the PVA aqueous solution, the conductive polymer PEDOT:PSS aqueous solution and the tannic acid aqueous solution is 1:2:

1.

7. A self-healing hydrogel supercapacitor prepared by the preparation method according to claim 1.

8. Use of the self-healing hydrogel supercapacitor according to claim 7 in the field of flexible and portable electronic devices.

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