Preparation method of high-strength and high-toughness integrated gelatin-based hydrogel supercapacitor

Abstract

The present invention discloses a method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor, specifically: adding carbon nanotubes to a gelatin aqueous solution, stirring, placing the gelatin / water / carbon nanotube solution in a glass mold, cooling and heat preservation, and forming a gel; immersing the gel in an aldehyde aqueous solution, immersing the aldehyde-crosslinked gelatin / carbon nanotube hydrogel in a salt solution, and obtaining a Gel / CNT gel; cutting the Gel / CNT gel into blocks and immersing them in a pyrrole / methanol mixture, using a template method to form a gelatin / carbon nanotube / polypyrrole electrode layer on the outer layer of the Gel / CNT gel, and then immersing it in a salt solution for swelling equilibrium. The present invention utilizes covalent crosslinking, nanofiller reinforcement, and the salting-out effect of protein to promote the hydrophobic association of gelatin combined with hydrogen bond crosslinking between gelatin molecular chains to give the hydrogel supercapacitor a multiple crosslinked structure, which significantly improves its mechanical strength and has strong toughness.

Description

Technical Field

[0001] The present invention belongs to the technical field of capacitor material preparation, and in particular relates to a method for preparing a high-strength and high-toughness integrated gelatin-based hydrogel supercapacitor. Background Art

[0002] With the update and iteration of electronic devices, electronic devices are increasingly developing in the direction of miniaturization, intelligence and wearability. Compared with traditional rigid electrode materials, flexible electrode materials have received widespread attention and concern in various fields because of their better ductility, high sensitivity and small size. Hydrogel is a polymer material with a three-dimensional network structure that can swell in water but is insoluble in water. Due to its unique solid-liquid coexistence characteristics, it has broad application prospects in biomedicine, flexible devices and other fields. Flexible supercapacitors based on conductive hydrogels show great market potential in biomedicine and new energy storage fields. Most of the flexible supercapacitors based on conductive hydrogels use a three-layer assembly structure of synthetic polymer hydrogels. However, synthetic polymers often have poor degradability. Compared with the three-layer assembly structure, the integrated structural design solves the interface stratification problem between the electrode and the gel electrolyte, and the interface diffusion resistance is greatly reduced. In the actual application process, there will be no electrode shedding or slippage caused by deformation. As a by-product in the leather and food fields, gelatin has the characteristics of being cheap, degradable, non-toxic and environmentally friendly. However, gelatin-based hydrogels often have poor strength and toughness, and it is difficult to meet the strength requirements for use in flexible electronic devices. Summary of the invention

[0003] The object of the present invention is to provide a method for preparing a high-strength and high-toughness integrated gelatin-based hydrogel supercapacitor.

[0004] The technical solution adopted by the present invention is a method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor, which is specifically implemented according to the following steps:

[0005] Step 1, mixing gelatin and water, and stirring until a uniform gelatin aqueous solution is formed;

[0006] Step 2, adding carbon nanotubes to the gelatin aqueous solution and stirring evenly to obtain a gelatin / water / carbon nanotube solution;

[0007] Step 3, placing the gelatin / water / carbon nanotube solution in a glass mold, cooling it to 0-4°C, and storing it at this temperature for 0.5-5h to form a gel;

[0008] Step 4, immersing the gel in an aldehyde aqueous solution to form a hydrogel, and immersing the aldehyde-crosslinked gelatin / carbon nanotube hydrogel in a salt solution to obtain a multi-crosslinked Gel / CNT gel;

[0009] Step 5, cutting the Gel / CNT gel into blocks, immersing the blocks in a pyrrole / methanol mixture at 0°C-4°C, and then using a template method to form a gelatin / carbon nanotube / polypyrrole electrode layer on the outer layer of the Gel / CNT gel, and then immersing them in a salt solution for swelling equilibrium to obtain a gelatin-based integrated supercapacitor.

[0010] The present invention is also characterized in that:

[0011] In step 1, the mass fraction of gelatin in the gelatin aqueous solution is 5%-15%; the stirring temperature is 35-60° C., and the stirring time is 10-60 min.

[0012] In step 4, the aldehyde aqueous solution is an aqueous solution containing an aldehyde compound, and the aldehyde compound is any one of formaldehyde, glutaraldehyde, aldehyde starch, aldehyde chitosan oligosaccharide, aldehyde trehalose, and aldehyde cellulose.

[0013] In step 5, the pyrrole / methanol mixed solution is prepared by mixing pyrrole and methanol in a volume ratio of 2:5; and the soaking time is 10 minutes.

[0014] In step 5, the specific process of the template method is: drop methyl orange solution on the Gel / CNT gel and spread it evenly, then drop oxidant solution on the surface of the gel, react for 5-25 hours, rinse the gel surface with deionized water to wash away the oxidant and unreacted pyrrole, and then form a gelatin / carbon nanotube / polypyrrole electrode layer.

[0015] The oxidant solution is prepared by mixing ferric chloride hexahydrate, disodium 2,6-naphthalene disulfonate, concentrated hydrochloric acid and deionized water in a mass ratio of 8:0.13:3:100.

[0016] In step 5, the salt solution is any one of ammonium sulfate solution, sodium sulfate solution, potassium sulfate solution, sodium carbonate solution, sodium sulfite solution, sodium dihydrogen phosphate solution, potassium carbonate solution, potassium sulfite solution, and potassium dihydrogen phosphate solution.

[0017] The beneficial effects of the present invention are as follows: the present invention restricts the diffusion of polypyrrole into the gelatin hydrogel substrate by chemically cross-linking gelatin, and prepares an electrode layer integrated with the gelatin hydrogel by in-situ polymerization of pyrrole on the surface of the gelatin hydrogel substrate, thereby solving the problem of electrode shedding or slippage caused by interface stratification and deformation between the electrode and the gel electrolyte of the three-layer assembled hydrogel supercapacitor. The capacitance (298F / g) of the supercapacitor prepared by the method of the present invention is significantly higher than that of the three-layer assembled hydrogel supercapacitor with gelatin-based conductive hydrogel as the electrode (75F / g). In addition, the present invention also utilizes covalent cross-linking, nanofiller reinforcement and the salting-out effect of protein to promote the hydrophobic association of gelatin and the hydrogen bond cross-linking between gelatin molecular chains to give the hydrogel supercapacitor a multiple cross-linked structure, which significantly improves its mechanical strength and has strong toughness. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a photograph of a high-strength and tough integrated gelatin-based hydrogel supercapacitor prepared by the method of the present invention;

[0019] Figure 2 CV curves of the high-strength and tough integrated gelatin-based hydrogel supercapacitor prepared in Example 1 at different scanning rates;

[0020] Figure 3 3 is a tensile stress-strain curve diagram of the gelatin-based hydrogel supercapacitor in Examples 1-4 of the present invention. DETAILED DESCRIPTION

[0021] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] The preparation method of the high-strength and toughness integrated gelatin-based hydrogel supercapacitor of the present invention is specifically implemented according to the following steps:

[0023] Step 1, mixing gelatin and water, and stirring at 35-60° C. for 10-60 minutes until a uniform gelatin aqueous solution is formed;

[0024] The mass fraction of gelatin in the gelatin aqueous solution is 5%-15%;

[0025] As a byproduct of leather and food, gelatin is cheap, degradable, non-toxic and environmentally friendly. Compared with the hydrogel supercapacitor with synthetic polymer as the base material, the hydrogel supercapacitor of the present invention has the advantages of being degradable and environmentally friendly.

[0026] Step 2, adding carbon nanotubes to the gelatin aqueous solution and stirring evenly to obtain a gelatin / water / carbon nanotube solution;

[0027] The amount of carbon nanotubes added is 0.1wt%-1wt%;

[0028] Step 3, placing the gelatin / water / carbon nanotube solution in a 120 mm×30 mm×1 mm glass mold, cooling to 0-4° C., and storing at this temperature for 0.5-5 h to form a gel;

[0029] Step 4, immersing the gel in an aldehyde aqueous solution with a concentration of 0.1wt%-1wt% for 5-15min to form a hydrogel, immersing the aldehyde-crosslinked gelatin / carbon nanotube hydrogel in a salt solution, utilizing the salting-out effect to promote the gelatin to form a hydrophobic association, and obtaining a multi-crosslinked gelatin / carbon nanotube hydrogel (Gel / CNT);

[0030] The amount of salt solution added is 10-30wt%; the soaking time is not less than 8h;

[0031] Aldehyde aqueous solution refers to an aqueous solution containing aldehyde compounds, and the aldehyde compound is any one of formaldehyde, glutaraldehyde, aldehyde starch, aldehyde chitosan oligosaccharide, aldehyde trehalose, and aldehyde cellulose;

[0032] Step 5, cutting the Gel / CNT gel into 3 cm × 3 cm blocks, soaking the blocks in a pyrrole / methanol mixture at 0°C-4°C, and then forming a gelatin / carbon nanotube / polypyrrole electrode layer on the outer layer of the Gel / CNT gel using a template method, and then soaking the blocks in a salt solution for swelling equilibrium to obtain a gelatin-based integrated supercapacitor;

[0033] The pyrrole / methanol mixture is prepared by mixing pyrrole and methanol in a volume ratio of 2:5; the soaking time is 10 minutes;

[0034] The specific process of the template method is as follows: drop methyl orange solution on the Gel / CNT gel and spread it evenly, then drop oxidant solution on the surface of the gel, react for 5-25 hours, rinse the surface of the gel with deionized water to wash away the oxidant and unreacted pyrrole, and then form a gelatin / carbon nanotube / polypyrrole electrode layer;

[0035] The oxidant solution is prepared by mixing ferric chloride hexahydrate, disodium 2,6-naphthalene disulfonate, concentrated hydrochloric acid and deionized water in a mass ratio of 8:0.13:3:100;

[0036] The salt solution is a salt having a salting-out effect on gelatin, specifically any one of ammonium sulfate solution, sodium sulfate solution, potassium sulfate solution, sodium carbonate solution, sodium sulfite solution, sodium dihydrogen phosphate solution, potassium carbonate solution, potassium sulfite solution, and potassium dihydrogen phosphate solution;

[0037] The method for preparing a supercapacitor of the present invention introduces covalent cross-linking, hydrogen bonding, hydrophobic association and nanofillers into a gelatin hydrogel matrix to form a multiple cross-linking structure, thereby improving the strength and toughness of the gelatin hydrogel matrix, and forms a gelatin, polypyrrole and carbon nanotube composite electrode layer integrated with the gelatin hydrogel matrix through an in-situ template coating method to prepare a gelatin-based integrated strong and tough supercapacitor.

[0038] Example 1

[0039] Mix gelatin and water at 45°C and stir for 30 minutes until a uniform gelatin aqueous solution is formed, and the mass fraction of gelatin in the gelatin aqueous solution is 10%; add 0.1wt% carbon nanotubes to the gelatin aqueous solution and stir evenly to obtain a gelatin / water / carbon nanotube solution. Place the solution in a 120mm×30mm×1mm glass mold, cool to 4°C, and store at this temperature for 1 hour to form a gel. Then, immerse the gel in a 0.1wt% glutaraldehyde aqueous solution for 10 minutes to form a hydrogel. The aldehyde-crosslinked gelatin / carbon nanotube hydrogel is immersed in a 30wt% ammonium sulfate solution for 12 hours, then cut into 3cm×3cm squares, and immersed in 0.075mL of pyrrole / methanol mixture for 10 minutes at 0°C. The gelatin / carbon nanotube / polypyrrole electrode layer is formed on the outer layer of the Gel / CNT gel by the template method. After pyrrole polymerization for 6 hours, the oxidant and unreacted pyrrole are washed with deionized water. Then the gel was immersed in a salt solution to swell and balance, and a gelatin-based integrated supercapacitor was obtained. The prepared gelatin-based hydrogel supercapacitor had a capacitance of 298F / g, and a tensile fracture stress and strain of 1.4MPa and 4.5, respectively.

[0040] Example 2

[0041] Mix gelatin and water at 45°C and stir for 30 minutes until a uniform gelatin aqueous solution is formed, and the mass fraction of gelatin in the gelatin aqueous solution is 10%. Add 0.6wt% carbon nanotubes to the gelatin aqueous solution and stir evenly to obtain a gelatin / water / carbon nanotube solution. Place the solution in a 120mm×30mm×1mm glass mold, cool to 2°C, and store at this temperature for 0.5h to form a gel. Then, immerse the gel in a 1wt% hydroformyl starch aqueous solution for 10min to form a hydrogel. The aldehyde-crosslinked gelatin / carbon nanotube hydrogel is immersed in a 30wt% salt solution for 10h, then cut into 3cm×3cm squares, and immersed in 0.075mL of pyrrole / methanol mixture for 10 minutes at 1°C. The gelatin / carbon nanotube / polypyrrole electrode layer is formed on the outer layer of the Gel / CNT gel by the template method. After pyrrole polymerization for 6h, the oxidant and unreacted pyrrole are washed with deionized water. Then the gel was immersed in a salt solution to swell and balance, and a gelatin-based integrated supercapacitor was obtained. The prepared gelatin-based hydrogel supercapacitor had a capacitance of 156F / g, and a tensile fracture stress and strain of 0.8MPa and 3.7, respectively.

[0042] Example 3

[0043] Mix gelatin and water at 55°C and stir for 20 minutes until a uniform gelatin aqueous solution is formed, and the mass fraction of gelatin in the gelatin aqueous solution is 10%. Add 0.8wt% carbon nanotubes to the gelatin aqueous solution and stir evenly to obtain a gelatin / water / carbon nanotube solution. Place the solution in a 120mm×30mm×1mm glass mold, cool to 4°C, and store at this temperature for 0.5h to form a gel. Then, immerse the gel in a 0.1wt% glutaraldehyde aqueous solution for 5min to form a hydrogel. Immerse the aldehyde-crosslinked gelatin / carbon nanotube hydrogel in a 30wt% sodium sulfate solution for 10h, then cut into 3cm×3cm squares, and soak in 0.075mL of pyrrole / methanol mixture for 10 minutes at 4°C. Use the template method to form a gelatin / carbon nanotube / polypyrrole electrode layer on the outer layer of the Gel / CNT gel. After pyrrole polymerization for 10h, wash the oxidant and unreacted pyrrole with deionized water. Then the gel was immersed in a salt solution to swell and balance, and a gelatin-based integrated supercapacitor was obtained. The prepared gelatin-based hydrogel supercapacitor had a capacitance of 268F / g, and a tensile fracture stress and strain of 1.0MPa and 4.3, respectively.

[0044] Example 4

[0045] The gelatin and water were mixed and stirred at 40°C for 50 minutes until a uniform gelatin aqueous solution was formed, and the mass fraction of gelatin in the gelatin aqueous solution was 10%. 0.1wt% carbon nanotubes were added to the gelatin aqueous solution and stirred evenly to obtain a gelatin / water / carbon nanotube solution. The solution was placed in a 120mm×30mm×1mm glass mold, cooled to 4°C, and stored at this temperature for 0.5h to form a gel. Then, the gel was immersed in a 0.5wt% hydroformylation chitosan aqueous solution for 5min to form a hydrogel. The aldehyde-crosslinked gelatin / carbon nanotube hydrogel was immersed in a 30wt% ammonium sulfate solution for 10h, then cut into 3cm×3cm squares, and immersed in 0.075mL of pyrrole / methanol mixture for 10 minutes at 3°C. The gelatin / carbon nanotube / polypyrrole electrode layer was formed on the outer layer of the Gel / CNT gel using the template method. After pyrrole polymerization for 8h, the oxidant and unreacted pyrrole were washed with deionized water. Then the gel was immersed in a salt solution to swell and balance, and a gelatin-based integrated supercapacitor was obtained. The prepared gelatin-based hydrogel supercapacitor had a capacitance of 192F / g, and a tensile fracture stress and strain of 0.7MPa and 4.6, respectively.

[0046] Figure 1 This is a photograph of a high-strength and tough integrated gelatin-based hydrogel supercapacitor prepared by the method of the present invention; the three-layer structure of the integrated gelatin-based hydrogel supercapacitor can be clearly seen from the figure.

[0047] Figure 2It is a CV curve diagram of the high-strength and tough integrated gelatin-based hydrogel supercapacitor prepared in Example 1 at different scanning rates; it shows that the capacitor has energy storage characteristics at different scanning rates; Figure 3 The tensile stress-strain curves of the gelatin-based hydrogel supercapacitors in Examples 1 to 4 of the present invention are shown in FIG. The fracture stress of the hydrogel capacitors in Examples 1 and 3 both reach above 1 MPa, and the fracture strain reaches above 4, which are strong and tough.

[0048] The above are only preferred embodiments of the present invention, and the scope of the present invention is not limited by them. The present invention may be modified and varied. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of patent protection of the present invention.

Claims

1. A method for preparing a high-strength and high-toughness integrated gelatin-based hydrogel supercapacitor, characterized in that: Follow the steps below to implement it: Step 1, mixing gelatin and water, and stirring until a uniform gelatin aqueous solution is formed; Step 2, adding carbon nanotubes to the gelatin aqueous solution and stirring evenly to obtain a gelatin / water / carbon nanotube solution; Step 3, placing the gelatin / water / carbon nanotube solution in a glass mold, cooling it to 0-4°C, and storing it at this temperature for 0.5-5h to form a gel; Step 4, immersing the gel in an aldehyde aqueous solution to form a hydrogel, and immersing the aldehyde-crosslinked gelatin / carbon nanotube hydrogel in a salt solution to obtain a multi-crosslinked Gel / CNT gel; Step 5, cutting the Gel / CNT gel into blocks, soaking the blocks in a pyrrole / methanol mixture at 0°C-4°C, and then forming a gelatin / carbon nanotube / polypyrrole electrode layer on the outer layer of the Gel / CNT gel using a template method, and then soaking the blocks in a salt solution for swelling equilibrium to obtain a gelatin-based integrated supercapacitor; The specific process of the template method is: drop methyl orange solution on the Gel / CNT gel and spread it evenly, then drop oxidant solution on the surface of the gel, react for 5-25 hours, rinse the surface of the gel with deionized water to wash away the oxidant and unreacted pyrrole, and then form a gelatin / carbon nanotube / polypyrrole electrode layer; the oxidant solution is a mixture of ferric chloride hexahydrate, disodium 2,6-naphthalene disulfonate, concentrated hydrochloric acid and deionized water in a mass ratio of 8:0.13:3:

100.

2. The method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor according to claim 1, characterized in that: In the step 1, the mass fraction of gelatin in the gelatin aqueous solution is 5%-15%; the stirring temperature is 35-60° C., and the stirring time is 10-60 min.

3. The method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor according to claim 1, characterized in that: In step 4, the aldehyde aqueous solution is an aqueous solution containing an aldehyde compound, and the aldehyde compound is any one of formaldehyde, glutaraldehyde, aldehyde starch, aldehyde chitosan oligosaccharide, aldehyde trehalose, and aldehyde cellulose.

4. The method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor according to claim 1, characterized in that: In step 5, the pyrrole / methanol mixed solution is prepared by mixing pyrrole and methanol in a volume ratio of 2:5; and the soaking time is 10 minutes.

5. The method for preparing a high-strength and tough integrated gelatin-based hydrogel supercapacitor according to claim 1, characterized in that: In step 5, the salt solution is any one of ammonium sulfate solution, sodium sulfate solution, potassium sulfate solution, sodium carbonate solution, sodium sulfite solution, sodium dihydrogen phosphate solution, potassium carbonate solution, potassium sulfite solution, and potassium dihydrogen phosphate solution.

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