Allyl functionalized hyaluronic acid hydrogel as well as preparation method and application thereof in electrolyte

Abstract

The invention discloses allyl functionalized hyaluronic acid hydrogel as well as a preparation method and application thereof in electrolyte, and belongs to the technical field of hydrogel electrolyte. And dissolving the modified hyaluronic acid in a solvent, sequentially adding a cross-linking agent, the modified chitin nanofibers and an initiator, carrying out polymerization reaction at a preset temperature for a preset time to obtain hydrogel, and soaking the hydrogel in an electrolyte to obtain the modified hyaluronic acid hydrogel electrolyte. According to the scheme, the existing problems that a traditional hydrogel electrolyte is prone to icing at low temperature, the ionic conductivity is suddenly reduced, and the mechanical performance is degraded are solved, and the mechanical strength is enhanced by constructing an allyl functionalized hyaluronic acid three-dimensional chemical cross-linked network; modified chitin nanofibers are introduced to bind water molecules through hydrogen bonds to inhibit growth of ice crystals, graphene quantum dots are added to optimize an ion transmission path, and the hydrogel electrolyte which still keeps high ionic conductivity, excellent freezing resistance and high mechanical strength at the low temperature of-40 DEG C is prepared.

Description

Technical Field

[0001] This invention relates to the field of hydrogel electrolyte technology, and in particular to an allyl-functionalized hyaluronic acid hydrogel, its preparation method, and its application in electrolytes. Background Technology

[0002] In recent years, with the increasing frequency of extreme weather events, the demand for high-performance, low-temperature resistant batteries has become increasingly urgent. Hydrogel electrolytes, due to their ease of preparation and environmental friendliness, have shown great application potential in the field of energy storage. However, in low-temperature environments, the large number of free water molecules inside traditional hydrogel electrolytes easily solidify into ice crystals, which obstructs ion transport channels, leading to a significant decrease in ionic conductivity and severe degradation of battery performance, greatly limiting their application in cold regions.

[0003] Hyaluronic acid is a substance containing a large number of hydrophilic groups. Due to its ability to form a cross-linked network with chitin nanofibers, it is widely used in hydrogel electrolytes for flexible batteries to improve their mechanical properties. However, when applying it to batteries, its performance under extreme environments, such as ionic conductivity at low and high temperatures, must be considered. Currently, although some methods exist to improve the low-temperature performance of hydrogel electrolytes, problems remain, including limited improvement in ionic conductivity and poor low-temperature cycle stability. Therefore, there is an urgent need to develop a hydrogel electrolyte that maintains good ionic conductivity and low-temperature performance even at -40°C. Summary of the Invention

[0004] The purpose of this invention is to provide an allyl-functionalized hyaluronic acid hydrogel, its preparation method, and its application in electrolytes. This invention addresses the existing problems of traditional hydrogel electrolytes, such as easy freezing at low temperatures, a sharp drop in ionic conductivity, and deterioration of mechanical properties. By constructing a three-dimensional chemical cross-linking network of allyl-functionalized hyaluronic acid to enhance mechanical strength, introducing modified chitin nanofibers to bind water molecules through hydrogen bonds to inhibit ice crystal growth, and adding graphene quantum dots to optimize ion transport pathways, a hydrogel electrolyte is prepared that maintains high ionic conductivity, excellent antifreeze properties, and high mechanical strength even at -40℃.

[0005] To achieve the above objectives, this invention discloses a method for preparing allyl-functionalized hyaluronic acid hydrogel. The hydrogel is formed by cross-linking photocatalytic allyl-functionalized hyaluronic acid with modified chitin nanofibers; the amount of modified chitin nanofibers added is 1.5 wt% of the mass of the photocatalytic allyl-functionalized hyaluronic acid. Photocatalytically functionalized hyaluronic acid was prepared by a photocatalytic allylation reaction, followed by purification. Modified chitin nanofibers were obtained through carboxymethylation and graphene quantum dot modification.

[0006] Preferably, the preparation process of the hydrogel specifically includes the following steps: S1. Photocatalytically functionalized hyaluronic acid was dissolved in ethylene glycol-water solution and stirred at 80°C until completely dissolved. After cooling to room temperature, the solution was sonicated and then magnetically stirred. N,N'-methylenebisacrylamide was added and magnetically stirred to obtain solution A. S2. Add graphene quantum dot modified chitin nanofiber aqueous solution to solution A, stir magnetically at room temperature, add ammonium persulfate, stir magnetically again to obtain ChNF-AHA hydrogel precursor solution. S3. After adding tetramethylethylenediamine to the ChNF-AHA hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place it in a vacuum oven at 60°C for 2 hours to obtain the hydrogel.

[0007] Preferably, the amount of photocatalytically functionalized hyaluronic acid added is 12-15 wt% of the mass of the ethylene glycol-water solution; In an ethylene glycol-water solution, the volume ratio of ethylene glycol to water is 3:7. The amount of N,N'-methylenebisacrylamide added is 0.15~0.18 wt% of the mass of photocatalytically functionalized hyaluronic acid; The amount of ammonium persulfate added is 0.7-1.0 wt% of the mass of photocatalytically allyl-functionalized hyaluronic acid. The molar ratio of ammonium persulfate to tetramethylethylenediamine is 1:0.8.

[0008] Preferably, the preparation process of photocatalytically functionalized hyaluronic acid specifically includes the following steps: S1-1. Dissolve hyaluronic acid in sodium bicarbonate solution and stir magnetically to form an aqueous solution of hyaluronic acid; S1-2. Allyl alcohol and photocatalyst are added to the solution obtained in step S1-1. Then, the mixture is magnetically stirred in a reactor equipped with a blue LED light source under a nitrogen atmosphere and at room temperature to obtain a mixed solution. S1-3. Place the mixed solution obtained in step S1-2 into a dialysis bag with a molecular weight cutoff of 8000-14000 Da, and dialyze it using deionized water for purification. S1-4. The solution purified by dialysis in step S1-3 is freeze-dried to obtain photocatalytically functionalized hyaluronic acid.

[0009] Preferably, in steps S1-2, the molar ratio of photocatalyst to hyaluronic acid monosaccharide units is (0.8-1.5):100; the irradiation wavelength of the blue LED light source is 450±10 nm, and the light intensity is 80~120 mW / cm². 2 .

[0010] Preferably, in steps S1-2, the photocatalyst is a 9-trimethylmethyl-10-methylacridine cation.

[0011] Preferably, in step S2, the preparation process of the graphene quantum dot modified chitin nanofiber aqueous solution specifically includes the following steps: S2-1. Take the chitin nanofiber aqueous dispersion, add NaOH solution, and stir magnetically; add monochloroacetic acid, heat for 3 h, add ethanol, and centrifuge to collect the precipitate; wash with ethanol, dissolve the precipitate in deionized water to obtain carboxymethylated chitin nanofiber dispersion. S2-2. Add graphene quantum dots and solid citric acid monohydrate to the above carboxymethylated chitin nanofiber dispersion; slowly add NaOH solution to adjust the pH of the mixed solution to 5-6; add anhydrous ethanol so that the volume ratio of ethanol to water in the mixed solution is (1-2):1; place the mixed solution in an oil bath and reflux at 90-100℃ for 12-24 hours; after the reaction is completed, allow it to cool naturally to room temperature to obtain an aqueous solution of graphene quantum dot modified chitin nanofibers.

[0012] Preferably, the amount of monochloroacetic acid added is 10-15 wt% of the dry weight of carboxymethyl chitin nanofibers; The amount of graphene quantum dots added is 5-15 wt% of the dry weight of carboxymethyl chitosan nanofibers; The oil bath temperature is preferably 100℃, and the reflux reaction time is preferably 18 h.

[0013] The present invention also provides an allyl functionalized hyaluronic acid hydrogel prepared by the above preparation method, wherein the allyl functionalized hyaluronic acid hydrogel is immersed in potassium hydroxide electrolyte to obtain the hydrogel electrolyte suitable for low-temperature batteries.

[0014] Therefore, the present invention has the following beneficial effects: This invention efficiently introduces high-density allyl double bonds into the hyaluronic acid molecular chain via photocatalysis, providing ample active sites for subsequent cross-linking. This allows for the construction of a dense and uniform three-dimensional network with chitin nanofibers, significantly improving the mechanical strength and structural stability of the hydrogel. Furthermore, the introduced chitin nanofibers, through their abundant hydrophilic groups, form strong hydrogen bonds with water molecules, effectively binding the movement of water molecules and inhibiting the formation of free ice crystals at low temperatures, thus giving the hydrogel excellent antifreeze and water retention properties. Simultaneously, the graphene quantum dots added to the composite system form conductive pathways, endowing the hydrogel with good conductivity.

[0015] The hydrogel electrolyte provided by this invention utilizes photocatalytically functionalized allyl hyaluronic acid (AHA) to construct a three-dimensional chemical cross-linked network, providing a robust mechanical framework. Graphene quantum dot-modified carboxymethyl chitin nanofibers (ChNF) serve as multifunctional physical cross-linking points, synergistically working with the polymer network to inhibit ice crystal growth and achieve low-temperature resistance. The addition of graphene quantum dots (GQDs) optimizes ion transport pathways and enhances the ionic conductivity of the hydrogel. The allyl functionalized hyaluronic acid hydrogel provided by this invention synergistically constructs both chemical and physical networks, exhibiting high mechanical strength, excellent antifreeze properties, and high ionic conductivity, making it suitable for use as a battery electrolyte.

[0016] The technical solution of the present invention will be further described in detail below through embodiments. Detailed Implementation

[0017] This invention provides a method for preparing modified hyaluronic acid and modified chitin nanofibers, comprising the following steps: The photocatalytic allyl functionalized hyaluronic acid preparation method is as follows: Hyaluronic acid is added to a NaHCO3 solution and magnetically stirred to obtain an aqueous hyaluronic acid solution. Allyl alcohol and 9-me-trimethyl-10-methylacridinium cation Mes-Acr are then added to the solution. + The mixture was placed in a reactor equipped with a blue LED light source and magnetically stirred under nitrogen atmosphere at room temperature to obtain a mixed solution. The mixed solution was transferred to a dialysis bag (8000-14000 Da) and dialyzed with deionized water for 36 h to remove unreacted allyl alcohol, photocatalyst, and their byproducts. The dialyzed solution was freeze-dried to obtain photocatalyzed allyl functionalized hyaluronic acid.

[0018] The modified chitosan nanofibers were prepared as follows: Aqueous dispersions of chitosan nanofibers were taken, and NaOH solution was added. The mixture was magnetically stirred at room temperature for 40 min. Monochloroacetic acid was added, and the reaction was carried out at 65 °C for 3 h. After the reaction, ethanol was added to precipitate the product, and the precipitate was collected by centrifugation. The product was washed three times with 70% ethanol aqueous solution to remove salts and unreacted chemicals. The purified carboxymethylated chitosan nanofibers were redispersed in deionized water to obtain a dispersion. Graphene quantum dots were added to the above carboxymethylated chitosan dispersion. Solid citric acid monohydrate was added to bring the dispersion concentration to 1.5 M. The pH of the mixed solution was adjusted to 5-6 using NaOH solution. Anhydrous ethanol was added to make the volume ratio of ethanol to water in the mixed solution (1-2):1. The mixed solution was placed in an oil bath and refluxed at 90-100 °C for 12-24 h. After the reaction, the mixture was allowed to cool naturally to room temperature. Dialysis was performed using a dialysis bag for 48 h to completely remove free citric acid. The concentrated dispersion after dialysis was ultrasonically treated in an ice-water bath for 1 h to obtain an aqueous solution of graphene quantum dot modified carboxymethyl chitin nanofibers.

[0019] The amount of monochloroacetic acid added is 10-15 wt% of the dry weight of carboxymethyl chitin nanofibers, preferably 12 wt%. The amount of graphene quantum dots added is 5-15 wt% of the dry weight of carboxymethyl chitin nanofibers, preferably 12 wt%. The oil bath temperature is preferably 100℃, and the reflux reaction time is preferably 18 h.

[0020] This invention also provides a method for preparing allyl-functionalized hyaluronic acid hydrogel, comprising the following steps: 1) Photocatalytic allyl functionalized hyaluronic acid (AHA) was dissolved in ethylene glycol-water solution and magnetically stirred at 80 °C. After complete dissolution, the solution was cooled to room temperature, sonicated for 20 min, magnetically stirred, and then N,N'-methylenebisacrylamide (MBAA) was added and magnetically stirred to obtain solution A.

[0021] 2) Add modified chitin nanofiber (ChNF) aqueous solution to solution A, stir magnetically at room temperature, add ammonium persulfate (APS), stir magnetically again to obtain ChNF-AHA hydrogel precursor solution.

[0022] 3) After adding tetramethylethylenediamine (TEMED) to the hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place the mold in a vacuum oven at 60 °C for 2 h to obtain the hydrogel.

[0023] In step 1) of the present invention, the amount of photocatalytically functionalized hyaluronic acid added is 12-15 wt.

[0024] In step 1) of the present invention, the volume ratio of ethylene glycol to water in the ethylene glycol-water solution is 3:7.

[0025] In step 1) of the present invention, the amount of N,N'-methylenebisacrylamide (MBAA) added is 0.15-0.18 wt% of the mass of AHA.

[0026] In step 2) of this invention, the amount of ammonium persulfate added is 0.7-1.0 wt% of the mass of AHA.

[0027] In step 2) of the present invention, the molar ratio of ammonium persulfate and tetramethylethylenediamine (TEMED) is 1:0.8.

[0028] A third aspect of the present invention provides the application of the hydrogel described in the above-mentioned technical solution or the allyl functionalized hyaluronic acid hydrogel prepared by the corresponding preparation method in a battery electrolyte. The photocatalytic allyl functionalized hyaluronic acid (AHA) hydrogel electrolyte is obtained by immersing the hydrogel or the allyl functionalized hyaluronic acid hydrogel prepared by the corresponding preparation method in KOH electrolyte for 24 h.

[0029] The technical solution of the present invention will be further described below through embodiments.

[0030] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0031] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. These other embodiments are also covered within the scope of protection of this invention.

[0032] Example 1 This embodiment provides an allyl-functionalized hyaluronic acid hydrogel electrolyte, the preparation method of which includes the following steps: A photocatalytic preparation of allyl-functionalized hyaluronic acid: 20g of hyaluronic acid was added to 4.2g of 0.05mol / L NaHCO3 solution, and the mixture was magnetically stirred (600rpm) for 30min to obtain an aqueous hyaluronic acid solution. Then, 30.57g of allyl alcohol and 0.363g of 9-mesinetrimethyl-10-methylacridinium cationic Mes-Acr were added to the solution. + The sample was placed in a reactor equipped with a blue LED light source, with an irradiation wavelength of 450±10 nm and a light intensity of 100 mW / cm². 2 The mixture was magnetically stirred (1500 rpm) at room temperature under nitrogen atmosphere for 2 h to obtain a mixed solution. The mixed solution was transferred to a dialysis bag (14000 Da) and dialyzed with deionized water for 36 h to remove unreacted allyl alcohol, photocatalyst and its byproducts. The dialyzed solution was freeze-dried to obtain 20 g of photocatalyst-functionalized allyl hyaluronic acid.

[0033] Preparation of modified chitin nanofiber aqueous solution: a) Take 1 g of chitosan nanofiber aqueous dispersion, add NaOH solution, and stir magnetically at room temperature for 40 min. Add 0.12 g of monochloroacetic acid and react at 65 ℃ for 3 h. After the reaction is complete, add ethanol to precipitate the product, and collect the precipitate by centrifugation. Wash three times with 70% ethanol, and redisperse the purified carboxymethylated chitosan nanofibers in deionized water to obtain a carboxymethylated chitosan nanofiber dispersion.

[0034] b) Add 0.12 g of graphene quantum dots to the above carboxymethylated chitin nanofiber dispersion. Add 10.5 g of citric acid monohydrate to achieve a dispersion concentration of 1.5 M. Adjust the pH of the mixture to 5 using NaOH solution. Add anhydrous ethanol to achieve a volume ratio of ethanol to water of 2:1 in the mixture. Place the mixture in an oil bath and reflux at 100 °C for 24 h. After the reaction is complete, allow it to cool naturally to room temperature.

[0035] c) Dialyze using a dialysis bag for 48 h to completely remove free citric acid. The concentrated dispersion after dialysis is then sonicated in an ice-water bath for 1 h to obtain 50 ml of an aqueous solution of graphene quantum dot-modified carboxymethylated chitin nanofibers.

[0036] Preparation of hydrogels and hydrogel electrolytes: 1) Dissolve 6.2g of photocatalytic allyl functionalized hyaluronic acid (AHA) in 50ml of ethylene glycol-water solution, stir magnetically at 80℃ (1500rpm) until completely dissolved, cool to room temperature, sonicate for 20 min, stir magnetically (600rpm) for 10 min, add 0.01g of N,N'-methylenebisacrylamide (MBAA), stir magnetically (600rpm) for 20 min to obtain solution A.

[0037] 2) Add 2 ml of modified chitin nanofiber (ChNF) aqueous solution to solution A, stir magnetically (1500 rpm) for 20 min at room temperature, add 0.05 g of ammonium persulfate (APS), and stir magnetically (600 rpm) for 30 min to obtain ChNF-AHA hydrogel precursor solution.

[0038] 3) After adding 0.02g of tetramethylethylenediamine (TEMED) to the hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place the mold in a vacuum oven at 60 ℃ for 2 h to obtain the hydrogel.

[0039] 4) Clean the surface of the hydrogel to remove unreacted precursor solution and other impurities, and immerse the hydrogel in KOH electrolyte for 24 h to obtain photocatalytic allyl functionalized hyaluronic acid (AHA) hydrogel electrolyte.

[0040] Example 2 This embodiment provides an allyl-functionalized hyaluronic acid hydrogel electrolyte, the preparation method of which includes the following steps: 1) Dissolve 6.7g of photocatalytic allyl functionalized hyaluronic acid (AHA) in 50ml of ethylene glycol-water solution, stir magnetically at 80℃ (1500rpm) until completely dissolved, cool to room temperature, sonicate for 20 min, stir magnetically (600rpm) for 10 min, add 0.01g of N,N'-methylenebisacrylamide (MBAA), stir magnetically (600rpm) for 20 min to obtain solution A.

[0041] 2) Add 3 ml of modified chitin nanofiber (ChNF) aqueous solution to solution A, stir magnetically (1500 rpm) for 20 min at room temperature, add 0.05 g of ammonium persulfate (APS), and stir magnetically (600 rpm) for 30 min to obtain ChNF-AHA hydrogel precursor solution.

[0042] 3) After adding 0.02g of tetramethylethylenediamine (TEMED) to the hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place the mold in a vacuum oven at 60 ℃ for 2 h to obtain the hydrogel.

[0043] 4) Clean the surface of the hydrogel to remove unreacted precursor solution and other impurities, and immerse the hydrogel in KOH electrolyte for 24 h to obtain photocatalytic allyl functionalized hyaluronic acid (AHA) hydrogel electrolyte.

[0044] In this embodiment, the preparation methods of photocatalytic allyl functionalized hyaluronic acid and modified chitin nanofiber aqueous solution are the same as in Example 1.

[0045] Example 3 This embodiment provides an allyl-functionalized hyaluronic acid hydrogel electrolyte, the preparation method of which includes the following steps: 1) Dissolve 7.2g of photocatalytic allyl functionalized hyaluronic acid (AHA) in 50ml of ethylene glycol-water solution, stir magnetically at 80℃ (1500rpm) until completely dissolved, cool to room temperature, sonicate for 20 min, stir magnetically (600rpm) for 10 min, add 0.01g of N,N'-methylenebisacrylamide (MBAA), stir magnetically (600rpm) for 20 min to obtain solution A.

[0046] 2) Add 4 ml of modified chitin nanofiber (ChNF) aqueous solution to solution A, stir magnetically (1500 rpm) for 20 min at room temperature, add 0.06 g of ammonium persulfate (APS), and stir magnetically (600 rpm) for 30 min to obtain ChNF-AHA hydrogel precursor solution.

[0047] 3) After adding 0.02g of tetramethylethylenediamine (TEMED) to the hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place the mold in a vacuum oven at 60 ℃ for 2 h to obtain the hydrogel.

[0048] 4) Clean the surface of the hydrogel to remove unreacted precursor solution and other impurities, and immerse the hydrogel in KOH electrolyte for 24 h to obtain photocatalytic allyl functionalized hyaluronic acid (AHA) hydrogel electrolyte.

[0049] In this embodiment, the preparation methods of photocatalytic allyl functionalized hyaluronic acid and modified chitin nanofiber aqueous solution are the same as in Example 1.

[0050] Comparative Example 1 This comparative example provides a hyaluronic acid hydrogel electrolyte, the preparation method of which includes the following steps: 1) Dissolve 7.2g of hyaluronic acid (AHA) in 50ml of ethylene glycol-water solution, stir magnetically at 80℃ (1500rpm) until completely dissolved, cool to room temperature, sonicate for 20 min, stir magnetically (600rpm) for 10 min, add 0.01g of N,N'-methylenebisacrylamide (MBAA), stir magnetically (600rpm) for 20 min to obtain solution A.

[0051] 2) Add 4 ml of chitin nanofiber (ChNF) aqueous solution to solution A, stir magnetically (1500 rpm) for 20 min at room temperature, add 0.06 g of ammonium persulfate (APS), and stir magnetically (600 rpm) for 30 min to obtain ChNF-AHA hydrogel precursor solution.

[0052] 3) After adding 0.02g of tetramethylethylenediamine (TEMED) to the hydrogel precursor solution, immediately pour it into a polytetrafluoroethylene mold and place the mold in a vacuum oven at 60 ℃ for 2 h to obtain the hydrogel.

[0053] 4) Clean the surface of the hydrogel to remove unreacted precursor solution and other impurities, and immerse the hydrogel in KOH electrolyte for 24 h to obtain hyaluronic acid (AHA) hydrogel electrolyte.

[0054] The hydrogel electrolytes prepared in the above embodiments and comparative examples were subjected to performance tests, namely, ionic conductivity and strain elongation, wherein: Ionic conductivity was measured using an electrochemical workstation and a high-low temperature chamber. The hydrogel was cut to 20 mm × 20 mm × 2 mm pieces, and a symmetrical cell was assembled using stainless steel sheets. The cell was placed in the high-low temperature chamber and connected to the electrochemical workstation. The AC impedance measurement parameters were set to a frequency of 10 Hz. -2 ~10 5 The conductivity was calculated using the formula σ=L / (R×S) with a signal amplitude of 5 mV and a Hz frequency. (L is the average thickness of the sample, S is the electrode contact area, and R is the bulk resistance of the hydrogel.)

[0055] The strain-tensile rate test was performed using a universal testing machine equipped with a tensile sensor and an environmental chamber. The hydrogel was prepared in a dumbbell shape, and the sample was aligned without skewing during clamping. The tensile rate was set to 1 mm / min and stopped when the sample completely broke.

[0056] The test results are shown in Table 1: Table 1 Performance Test Results

[0057] As can be seen from the above embodiments, the hydrogel provided by the present invention has an ionic conductivity ≥ 200 mS·cm at room temperature. -1 Ionic conductivity at -40 ℃ ≥ 8 mS·cm -1 The strain elongation is ≥ 400%. In Comparative Example 1, both the hyaluronic acid and chitin nanofibers are unmodified. Unmodified hyaluronic acid lacks allyl functionalization and relies solely on a small number of hydroxyl groups on the hyaluronic acid molecular chain for chemical cross-linking via the cross-linking agent MBAA. This results in extremely low cross-linking density, a loose network structure, and slow, circuitous ion transport. Furthermore, the unmodified chitin nanofibers contain hydrophobic groups on their surface, making them prone to aggregation in ethylene glycol-water solutions, thus disrupting ion transport channels.

[0058] Therefore, this invention provides an allyl-functionalized hyaluronic acid hydrogel, its preparation method, and its application, solving the existing problems of traditional hydrogel electrolytes such as easy freezing at low temperatures, sharp drop in ionic conductivity, and deterioration of mechanical properties. By constructing an allyl-functionalized hyaluronic acid three-dimensional chemical cross-linking network to enhance mechanical strength, introducing modified chitin nanofibers to bind water molecules through hydrogen bonds to inhibit ice crystal growth, and adding graphene quantum dots to optimize ion transport pathways, a hydrogel electrolyte that maintains high ionic conductivity, excellent antifreeze properties, and high mechanical strength at a low temperature of -40℃ is prepared.

[0059] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. Use of an allyl-functionalized hyaluronic acid hydrogel, characterized in that, The allyl-functionalized hyaluronic acid hydrogel is soaked in a potassium hydroxide electrolyte, so as to obtain the hydrogel electrolyte suitable for low-temperature batteries.

2. An allyl-functionalized hyaluronic acid hydrogel, characterized in that, The application is used to realize the application as claimed in claim 1.

3. A process for the preparation of an allyl-functionalized hyaluronic acid hydrogel according to claim 2, characterized in that, The hydrogel is formed by cross-linking photocatalytic allyl-functionalized hyaluronic acid and modified chitin nanofibers; the addition amount of the modified chitin nanofibers is 1.5 wt% of the mass of the photocatalytic allyl-functionalized hyaluronic acid. The photocatalytic allyl-functionalized hyaluronic acid is prepared through a photocatalytic allylation reaction, and is obtained after purification treatment; The modified chitin nanofibers are obtained through carboxymethylation and graphene quantum dot modification treatment.

4. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 3, characterized in that, The preparation process of the hydrogel specifically includes the following steps: S1, dissolve the photocatalytic allyl-functionalized hyaluronic acid in a glycol-water solution, stir at 80℃ until completely dissolved, cool to room temperature, magnetically stir after ultrasonic treatment, add N,N'-methylene bisacrylamide, magnetically stir, and obtain solution A; S2, add the graphene quantum dot modified chitin nanofiber aqueous solution to solution A, magnetically stir at room temperature, add ammonium persulfate, magnetically stir, and obtain the ChNF-AHA hydrogel precursor solution; S3, after adding tetramethyl ethylenediamine to the ChNF-AHA hydrogel precursor solution, immediately pour into a polytetrafluoroethylene mold, and place in a 60℃ vacuum oven for 2h, and obtain the hydrogel.

5. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 4, characterized in that, The addition amount of the photocatalytic allyl-functionalized hyaluronic acid is 12-15 wt% of the mass of the glycol-water solution; In the glycol-water solution, the volume ratio of glycol to water is 3:7; The addition amount of N,N'-methylene bisacrylamide is 0.15-0.18 wt% of the mass of the photocatalytic allyl-functionalized hyaluronic acid; The addition amount of ammonium persulfate is 0.7-1.0 wt% of the mass of the photocatalytic allyl-functionalized hyaluronic acid; The molar ratio of ammonium persulfate to tetramethyl ethylenediamine is 1:0.

8.

6. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 4, characterized in that, The preparation process of the photocatalytic allyl-functionalized hyaluronic acid specifically includes the following steps: S1-1, dissolve hyaluronic acid in a sodium bicarbonate solution, and magnetically stir to form a hyaluronic acid aqueous solution; S1-2, add allyl alcohol and a photocatalyst to the solution obtained in step S1-1, and then magnetically stir in a reactor equipped with a blue LED light source under a nitrogen atmosphere and at room temperature to obtain a mixed solution; S1-3, place the mixed solution obtained in step S1-2 in a dialysis bag with a molecular weight cut-off of 8000-14000 Da, and perform dialysis purification with deionized water; S1-4, freeze-dry the solution after dialysis purification in step S1-3 to obtain photocatalytic allyl-functionalized hyaluronic acid.

7. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 6, characterized in that, In step S1-2, the molar ratio of the photocatalyst to the hyaluronic acid monosaccharide unit is (0.8-1.5):100; the irradiation wavelength of the blue LED light source is 450±10 nm, and the light intensity is 80-120 mW / cm 2 .

8. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 6, characterized in that, In step S1-2, the photocatalyst is 9-mesityl-10-methyl acridine cation.

9. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 4, characterized in that, The preparation process of the graphene quantum dot modified chitin nanofiber aqueous solution in step S2 specifically includes the following steps: S2-1, take a chitin nanofiber aqueous dispersion, add a NaOH solution, and magnetically stir; add monochloroacetic acid, heat for 3h, add ethanol, and centrifuge to collect the precipitate; after washing with ethanol, dissolve the precipitate in deionized water to obtain a carboxymethylated chitin nanofiber dispersion; S2-2, adding graphene quantum dots to the carboxymethylated chitin nanofiber dispersion solution, adding solid citric acid monohydrate; slowly drop NaOH solution, adjust the pH value of the mixed solution to 5-6; add anhydrous ethanol, so that the volume ratio of ethanol to water in the mixed solution is (1-2):1; place the mixed solution in an oil bath, reflux at 90-100℃ for 12-24 hours; after the reaction is completed, naturally cool to room temperature to obtain a graphene quantum dot modified chitin nanofiber aqueous solution.

10. The method for preparing an allyl-functionalized hyaluronic acid hydrogel according to claim 9, characterized in that, The amount of monochloroacetic acid added is 10-15 wt% of the dry weight of the carboxymethyl chitin nanofiber; The amount of graphene quantum dots added is 5-15 wt% of the dry weight of the carboxymethyl chitin nanofiber; The oil bath temperature is preferably 100℃, and the reflux reaction time is preferably 18 h.

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