Hydrogel and preparation method thereof, hydrogel electrolyte, flexible battery and wearable intelligent equipment

Abstract

The invention discloses hydrogel and a preparation method thereof, hydrogel electrolyte, a flexible battery and wearable intelligent equipment, and relates to the technical field of batteries, the hydrogel is prepared from chitin, polyvinyl alcohol and alpha-helix protein, through the synergistic effect of the three materials, by means of the chemical and physical double-crosslinking stable structure of the chitin, the hydrogel electrolyte is prepared, and the hydrogel electrolyte is prepared. According to the preparation method disclosed by the invention, a high-efficiency ionic conduction network structure can be finally formed by using the alpha-helical protein and the unique alpha-helical structure of the alpha-helical protein, and the network structure also has excellent mechanical properties, so that the hydrogel with high ionic conductivity and strong mechanical properties is prepared.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly relates to a hydrogel, a preparation method thereof, a hydrogel electrolyte, a flexible battery, and a wearable intelligent device. Background Art

[0002] With the rise of new types of portable and wearable intelligent electronic products and devices, flexible batteries have seen a huge market demand. Currently, the mainstream lithium-ion batteries in the market face problems such as limited lithium resource reserves, significant safety hazards brought by lithium dendrite problems, and high costs. Flexible zinc metal batteries have become strong candidates for future energy storage applications due to their potential high energy storage capacity, environmental friendliness, high safety, easy assembly, and high theoretical capacity of the zinc anode.

[0003] Currently, flexible zinc metal batteries usually use semi-solid polymers as electrolytes, which can effectively overcome the problem of liquid electrolyte leakage and simultaneously act as both a separator and an electrolyte. Hydrogel polymer electrolytes with excellent flexibility and structural designability are the focus of current research. However, existing hydrogels still face problems such as low ionic conductivity and low mechanical strength, and the preparation process is relatively complex and the production cost is high, which greatly limits their practical applications and performance. Therefore, it is crucial to develop hydrogels with high ionic conductivity, strong mechanical properties, and low cost to meet the needs of future energy storage. Summary of the Invention

[0004] The main object of the present invention is to propose a hydrogel, a preparation method thereof, a hydrogel electrolyte, a flexible battery, and a wearable intelligent device, aiming to improve the problems of poor ionic conductivity, low water retention rate, and low mechanical strength of hydrogels in the prior art.

[0005] To achieve the above object, the hydrogel proposed by the present invention has a material including chitin, polyvinyl alcohol, and α-helical protein.

[0006] In one embodiment, the mass ratio of the chitin, the polyvinyl alcohol, and the α-helical protein is (2 - 3):4:(1 - 2).

[0007] The present invention also proposes a preparation method of the hydrogel as described above, and the preparation steps include:

[0008] S10, mixing chitin with a first solvent and performing a freeze-thaw cycle operation to obtain a chitin solution;

[0009] S20, mixing a protein product with a second solvent, concentrating and dialyzing to obtain α-helical protein;

[0010] S30. Prepare an aqueous solution of polyvinyl alcohol, mix and stir the aqueous polyvinyl alcohol solution with the α-helical protein solution and the chitin solution to obtain a mixed solution;

[0011] S40. Mix the mixed solution with a crosslinking agent to carry out a crosslinking reaction, freeze, and dry to obtain a hydrogel.

[0012] In one embodiment, in step S10:

[0013] The first solvent includes NaOH, urea, and water, and the mass ratio of the chitin to the first solvent is (4 - 6):100; and / or,

[0014] The concentration of chitin in the chitin solution is (4 - 6) wt%;

[0015] In step S20:

[0016] The second solvent includes urea, sodium dodecyl sulfate, and sodium sulfide, and the molar ratio of the urea, the sodium dodecyl sulfate, and the sodium sulfide is (60 - 100):1:1; and / or,

[0017] The protein product includes wool fibers; and / or,

[0018] The mixing of the wool fibers with the second solvent includes: adding 0.1 - 0.5 grams of the wool fibers per milliliter of the second solvent.

[0019] In one embodiment, step S30 includes:

[0020] S301. Mix and subject to an oil bath polyvinyl alcohol and glycerol to obtain an aqueous polyvinyl alcohol solution;

[0021] S302. Mix and stir the aqueous polyvinyl alcohol solution with the α-helical protein solution and the chitin solution to obtain a mixed solution.

[0022] In one embodiment, in the polyvinyl alcohol solution, the concentration of the polyvinyl alcohol is 18 - 22 wt.%; and / or,

[0023] In the α-helical protein solution, the concentration of the α-helical protein is (4 - 6) wt%; and / or,

[0024] The volume ratio of the aqueous polyvinyl alcohol solution to the α-helical protein solution and the chitin solution is 1:(1 - 2):(1 - 2).

[0025] In one embodiment, step S40 includes:

[0026] S401. Mix the mixed solution with a crosslinking agent to carry out a chemical crosslinking reaction to obtain a preliminarily crosslinked solution;

[0027] S402. Mix the initial cross-linking solution with hydrochloric acid for physical cross-linking to obtain a gel solution;

[0028] S403. Subject the gel solution to low-temperature treatment, freezing, and drying to obtain a hydrogel;

[0029] Wherein, the cross-linking agent includes epichlorohydrin, and the mixing of the mixed solution with the cross-linking agent includes: adding 15-20 grams of the mixed solution per milliliter of epichlorohydrin.

[0030] The present invention provides a hydrogel electrolyte, which includes a hydrogel and an electrolyte salt. The electrolyte salt includes a zinc salt, and the hydrogel includes the above-mentioned hydrogel or a hydrogel prepared by the preparation method of the hydrogel described in any one of the above.

[0031] The present invention also proposes a flexible battery, which includes the above-mentioned hydrogel electrolyte.

[0032] The present invention also proposes a wearable smart device, which includes the above-mentioned flexible battery.

[0033] The technical solution of the present invention prepares a hydrogel by using raw materials of chitin, polyvinyl alcohol, and α-helical protein. Among them, polyvinyl alcohol provides a basic polymer with good hydration ability and can form a network structure with high ion migration efficiency. Chitin contains abundant amino and hydroxyl groups, providing more ion transport channels. α-helical protein can provide a flexible and dynamic structure to promote the movement of ions in the electrolyte. Through the synergistic effect of the three materials, using the chemical and physical double cross-linking of chitin to stabilize the structure and the unique α-helical structure of α-helical protein, an efficient ion conduction network structure can be finally formed, and this network structure has excellent mechanical properties at the same time, thus achieving the preparation of a hydrogel with high ionic conductivity and strong mechanical properties. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0035] Figure 1 Schematic diagram of the product of the hydrogel prepared in Example 1 provided by the present invention;

[0036] Figure 2 Tensile strength curve graph of the hydrogel prepared in Example 1 provided by the present invention;

[0037] Figure 3 This is the water retention rate test result of the hydrogel prepared in Example 1 of the present invention.

[0038] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0041] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0042] Currently, flexible zinc metal batteries usually use semi-solid polymers as electrolytes, which can effectively overcome the problem of liquid electrolyte leakage and simultaneously act as both a separator and an electrolyte. Hydrogel polymer electrolytes with excellent flexibility and structural designability are the focus of current research. However, existing hydrogels still face problems such as low ionic conductivity and low mechanical strength, and the preparation process is relatively complex and the production cost is relatively high, which greatly limits their practical applications and performance. Therefore, in order to meet the needs of future energy storage, it is crucial to develop hydrogels with high ionic conductivity, strong mechanical properties and low cost.

[0043] The present invention provides a hydrogel, and the materials of the hydrogel include chitin, polyvinyl alcohol and α-helical protein.

[0044] The technical solution of the present invention prepares a hydrogel by using raw materials of chitin, polyvinyl alcohol and α-helical protein. Among them, polyvinyl alcohol provides a basic polymer with good hydration ability and can form a network structure with high ion migration efficiency. Chitin contains abundant amino and hydroxyl groups, providing more ion transport channels. The α-helical protein can provide a flexible and dynamic structure to promote the movement of ions in the electrolyte. Through the synergistic effect of the three materials, the chemical and physical double cross-linking of chitin is used to stabilize the structure, and the unique α-helical structure of the α-helical protein is utilized to finally form an efficient ion conduction network structure, and this network structure has excellent mechanical properties at the same time, thereby realizing the preparation of a hydrogel electrolyte with high ionic conductivity and strong mechanical properties.

[0045] In an embodiment of the present invention, the mass ratio of the chitin, the polyvinyl alcohol and the α-helical protein is (2-3):4:(1-2). Within the above mass range, an efficient ion conduction network structure can be formed, and this network structure has excellent mechanical properties at the same time, thereby realizing the preparation of a hydrogel with high ionic conductivity and strong mechanical properties.

[0046] The present invention also provides a preparation method of the hydrogel as described above. The preparation steps include:

[0047] S10, mixing chitin with a first solvent and performing a freeze-thaw cycle operation to obtain a chitin solution;

[0048] S20, mixing a protein product with a second solvent, concentrating and dialyzing to obtain α-helical protein;

[0049] S30, preparing a polyvinyl alcohol aqueous solution, mixing the polyvinyl alcohol aqueous solution with the α-helical protein solution and the chitin solution, and stirring to obtain a mixed solution;

[0050] S40, mixing the mixed solution with a cross-linking agent for cross-linking reaction, freezing and drying to obtain a hydrogel.

[0051] Adopting the above preparation process, through multi-step mixing, it has the advantages of simple operation, low cost, good repeatability, etc.

[0052] In an embodiment of the present invention, in step S10: the first solvent includes NaOH, urea, and water, and the mass ratio of the chitin to the first solvent is (4-6):100. The addition of the first solvent is to promote the dissolution of chitin. The mass ratio of the chitin to the first solvent being 4-6:100 can be 4:100, 5:100, or 6:100. Within this range, the dissolution effect is better. Preferably, the mass ratio of the chitin, NaOH, urea, and water being 1:2:1:17 is even better.

[0053] Further, in step S10, the freeze-thaw operation is to make the chitin solution more uniform and form a stable solution.

[0054] In an embodiment of the present invention, the concentration of chitin in the chitin solution is (4-6) wt%. Within this concentration range, the chitin can fully react completely without wasting raw materials excessively.

[0055] Specifically, the operation steps of step S10 include: mixing the crude chitin powder with the first solvent at a ratio of 4-6:100. Among them, NaOH, urea, and deionized water are mixed at a mass ratio of 2:1:17. After mixing, perform 5 cycles of freeze-thaw operation to form a colorless and transparent chitin solution. Centrifuge the obtained colorless and transparent chitin solution in a constant-temperature centrifuge to obtain a pure chitin solution without bubbles and impurities, and store it in a refrigerator at 4°C for subsequent use.

[0056] It can be understood that the main component in wool fibers is keratin, which is a natural protein with an α-helical structure, and it has a wide source. By using the second solvent to break the cross-linked structure of wool fibers, the keratin is extracted from the fibers and the α-helical structure is maintained.

[0057] In an embodiment of the present invention, in step S20, the second solvent includes urea, sodium dodecyl sulfate, and sodium sulfide. The second solvent is used to dissolve the protein to obtain α-helical protein.

[0058] Specifically, in the second solvent, the molar ratio of the urea, the sodium dodecyl sulfate, and the sodium sulfide is (60-100):1:1.

[0059] The present invention extracts α-helical protein by a reduction method, using a high-concentration urea solution with a concentration of about 6-10 mol / L, and adding a small amount of sodium dodecyl sulfate and sodium sulfide, both with a concentration of about 0.1 mol / L. Among them, sodium sulfide is a reducing agent that can break the disulfide bonds crosslinking between wool keratin molecules. Its concentration directly affects the solubility of wool fibers, but also affects the solution viscosity. And too high a concentration will increase the alkalinity of the solution, resulting in hydrolysis of protein macromolecules, which is not conducive to obtaining α-helical protein. Therefore, the dosage should not be too high. High-concentration urea (it can play a role when the concentration is greater than 4 mol / L) is a protein denaturant, which is used to break the hydrogen bonds between protein molecules so that the protein macromolecules are in an extended state or directly denatured. Sodium dodecyl sulfate is a surfactant that can inhibit the crosslinking between keratin macromolecules in this system and at the same time act as a stabilizer to protect the helical structure of protein molecules.

[0060] To make the extraction effect better, in step S20, the protein product includes wool fibers, and the mixing of the wool fibers and the second solvent includes: adding 0.1-0.5 g of the wool fibers to each milliliter of the second solvent.

[0061] Specifically, the operation steps of step S20 include: cleaning the wool fibers with acetone and ethanol to remove surface impurities such as grease. After cleaning, dissolving them with the second solvent to release the protein, filtering to obtain a crude protein solution, loading the crude protein solution into a dialysis bag for retention, filtering with deionized water multiple times to remove impurities, and then concentrating, freeze-drying to obtain α-helical protein.

[0062] In the embodiment of the present invention, step S301 includes: mixing polyvinyl alcohol and glycerol and performing an oil bath to obtain an aqueous polyvinyl alcohol solution. This step is to dissolve the polyvinyl alcohol to prepare an aqueous polyvinyl alcohol solution.

[0063] Furthermore, the concentration of the aqueous polyvinyl alcohol solution is (18-22) wt%, preferably 20 wt%. In this concentration range, polyvinyl alcohol can be mixed with the subsequent solution system and serve as a network structure scaffold for the hydrogel to obtain a relatively stable hydrogel product.

[0064] In the embodiment of the present invention, step S302 includes mixing the aqueous polyvinyl alcohol solution with the α-helical protein solution and the chitin solution and stirring to obtain a mixed solution.

[0065] In this step, the aqueous polyvinyl alcohol solution, the chitin solution and the α-helical protein solution are fully mixed, and finally a crosslinked network structure with high mechanical strength can be formed.

[0066] Further, to ensure a sufficient reaction, the volume ratio of the polyvinyl alcohol aqueous solution, the α-helical protein solution, and the chitin solution is 1:(1-2):(1-2). Within this range, polyvinyl alcohol provides a scaffold structure, and chitin serves as a supplement to the structural scaffold, further stabilizing the structure. The α-helical protein can form a specific coordination with zinc ions in the zinc salt of the electrolyte, thereby achieving ultra-high ionic conductivity. Preferably, the volume ratio of 1:1:2 is even better.

[0067] In an embodiment of the present invention, step S40 includes:

[0068] S401, mixing the mixed solution with a crosslinking agent to carry out a chemical crosslinking reaction to obtain a primary crosslinked solution;

[0069] S402, mixing the primary crosslinked solution with hydrochloric acid to carry out physical crosslinking to obtain a gel solution;

[0070] S403, subjecting the gel solution to low-temperature treatment, freezing, and drying to obtain a hydrogel.

[0071] The above steps are mainly to enable a crosslinking reaction to occur in the mixed reaction and improve the mechanical properties of the hydrogel. Hydrochloric acid can cause some chitin molecular chains to be arranged and stacked in parallel under force in the liquid phase environment through strong self-cohesion, achieving physical crosslinking. Through the crosslinking reaction, a hydrogel with good stability, electrical conductivity, and mechanical properties can be obtained.

[0072] In step S40, the crosslinking agent includes epichlorohydrin. The mixing of the mixed solution and the crosslinking agent includes: adding 15-20 grams of the mixed solution to each milliliter of epichlorohydrin to ensure a sufficient crosslinking reaction.

[0073] Specifically, the operating steps of step S40 include:

[0074] In an embodiment of the present invention, the present invention provides a hydrogel electrolyte, which includes a hydrogel and an electrolyte salt. The electrolyte salt includes a zinc salt, and the hydrogel includes the above-mentioned hydrogel or the hydrogel prepared by the preparation method of any one of the above.

[0075] It should be noted that to prepare the hydrogel electrolyte, the hydrogel material needs to be mixed with the electrolyte salt. Here, the electrolyte salt is selected as the zinc salt and added to the α-helical protein solution during the preparation process because zinc ions will form a specific coordination with α-helical protein. As an electrolyte, it can achieve a low transport energy barrier and a short transport distance, realizing ultra-high ionic conductivity.

[0076] The present invention also proposes a flexible battery, including the above-mentioned hydrogel electrolyte.

[0077] It is understandable that a flexible battery is a battery that can be bent, folded or twisted, designed to adapt to various shapes and application scenarios, such as wearable devices, flexible electronic devices, etc. Usually, a hydrogel electrolyte is sandwiched between the positive electrode and the negative electrode to form the structure of the flexible battery. Since the flexible battery includes the hydrogel, it has all the technical solutions of the above-mentioned hydrogel, and thus also has all the beneficial effects brought by the above technical solutions, which will not be elaborated here one by one.

[0078] The present invention also proposes a wearable intelligent device, including the flexible battery as described above. The demonstration examples of the wearable intelligent device can be electronic watches, earphones or other similar products. It has all the technical solutions of the above-mentioned hydrogel, and thus also has all the beneficial effects brought by the above technical solutions, which will not be elaborated here one by one.

[0079] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present invention and are not used to limit the present invention.

[0080] Embodiment 1

[0081] The preparation of a hydrogel electrolyte is as follows:

[0082] 1) Preparation of chitin solution: Coarse chitin raw material powder (without prior purification) is mixed with NaOH, urea, and deionized water in a mass ratio of 5:10:5:85, and stirred with a magnetic stirrer at room temperature for 30 minutes to dissolve NaOH and urea, promoting uniform mixing of the raw materials. Then the mixed solution is placed in a low-temperature box pre-cooled to -60°C in advance and frozen for 12 h, then taken out and thawed at room temperature for 3 h, and then placed in a magnetic stirrer and stirred for 1 h (manual assistance with a glass rod is required for the first stirring). Such a freeze-thaw cycle is carried out 5 times to form a colorless and transparent chitin solution. The obtained transparent chitin solution is centrifuged at 8000 rpm for 10 min in a constant-temperature centrifuge at 0°C to obtain a pure 5 wt.% chitin solution without bubbles and impurities, and stored in a refrigerator at 4°C for subsequent use.

[0083] 2) Extraction of α-helical protein: Immerse wool fibers in acetone for 4 hours, then wash them three times with ethanol to remove grease and impurities. Immerse the washed wool fibers in an aqueous solution containing urea (8M), sodium dodecyl sulfate (0.1M), and sodium sulfide (0.1M) at a mass concentration of 0.1 g / mL, stir at 60 °C for 8 h, and filter to obtain a yellow crude keratin solution. Load the crude keratin solution into a dialysis bag with a molecular weight cut-off of 3500 D and dialyze it in deionized water for 3 days to remove protein denaturants and reducing agents. During dialysis, change the deionized water every 4 h to ensure that the volume ratio of deionized water to the dialysis solution remains at about 100:1. Finally, concentrate the dialyzed keratin solution and obtain white α-helical protein powder after freeze-drying.

[0084] 3) Preparation of chitin / α-helical protein / polyvinyl alcohol mixed solution: Add polyvinyl alcohol and glycerol to deionized water at a mass ratio of 7:1, stir in an oil bath at 90 °C for 5 h to obtain a homogeneous 20 wt.% polyvinyl alcohol aqueous solution. Then add α-helical protein powder to deionized water and add zinc trifluoromethanesulfonate at 1 mol / L, stir at room temperature for 2 h to obtain a homogeneous 5 wt.% α-helical protein solution. Mix the polyvinyl alcohol solution with the α-helical protein solution containing Zn 2+ in a volume ratio of 1:1, continue to stir at room temperature for 2 h to form a homogeneous mixed solution. Then transfer the mixed solution to a 0 °C constant temperature ice-water bath, mix it with a pre-prepared 5 wt.% chitin aqueous solution in a volume ratio of 1:1, and continue to stir for 1 h to form a homogeneous mixed solution.

[0085] 4) Preparation of hydrogel for zinc metal battery: In a 0 °C constant temperature ice-water bath, under continuous magnetic stirring, dropwise add the cross-linking agent epichlorohydrin into the chitin / α-helical protein / polyvinyl alcohol solution through a constant pressure dropping funnel (the component ratio is cross-linking agent: solution = 50 mL: 1000 g) to chemically cross-link the chitin solution and obtain a preliminarily cross-linked gel. Then quickly place the gel in a 0.1 M hydrochloric acid solution for 30 s to cause some chitin molecular chains to be arranged and stacked parallelly under force in the liquid phase environment through strong self-cohesion, realizing physical cross-linking. Quickly pour the preformed gel into a mold and perform low-temperature treatment in an incubator at 4 °C for 12 h to obtain a formed hydrogel. Then soak the gel in ethanol and deionized water for 2 h and 48 h respectively, keep the liquid circulating continuously to thoroughly wash away residual reagents such as acids and alkalis, and then obtain the final product after freeze-drying.

[0086] Example 2

[0087] The difference between Example 2 and Example 1 is that: the mass ratio of the chitin, the polyvinyl alcohol, and the α-helical protein is 3 ： 4:1.

[0088] Example 3

[0089] The difference between Example 2 and Example 1 is that: the mass ratio of the chitin, the polyvinyl alcohol and the α-helical protein is 1 ： 2:1.

[0090] Comparative Example 1

[0091] The difference between Comparative Example 1 and Example 1 is that α-helical protein is not added in Comparative Example 1.

[0092] Performance Test

[0093] 1) The hydrogel product prepared in Example 1 is as Figure 1 shown. It can be seen from Figure 1 the optical photograph of the hydrogel product prepared in Example 1 that the product presents a relatively transparent gel film shape.

[0094] 2) Tensile strength test:

[0095] Test method: Pour the hydrogels prepared in the examples and comparative examples into a mold, demold after curing to obtain standard specimens, fix the specimens between the upper and lower clamps of a universal material testing machine, conduct the test, and record the tensile strength. Among them, the calculation formula for the tensile strength (σ) is: σ = F / S, where F is the maximum tensile force that can be borne, and S is the cross-sectional area.

[0096] The test results are as Figure 2 shown in and Table 1:

[0097] Table 1

[0098] Tensile strength (Mpa) Example 1 2.24 Example 2 2.03 Example 3 2.18 Comparative Example 1 1.86

[0099] From Figure 2 it can be obtained the tensile strength test curves of the hydrogel products prepared in the examples and comparative examples. Thus, it can be known that by using the chemical and physical double-crosslinked stable structure of chitin and the unique α-helical structure of α-helical protein, a network structure with excellent mechanical properties can be finally formed. The highest tensile strength value corresponding to Example 1 is 2.24 MPa, and all the examples are above 2 MPa. However, due to the non-addition of α-helical protein in the comparative example, the tensile strength decreases.

[0100] 3) Water retention rate test:

[0101] Test method: Place the hydrogel prepared in Example 1 in an environment with a relative humidity of 30% and a temperature of 25 °C to evaluate the water retention ability of the hydrogel. Use an electronic scale to record the weight of the hydrogel every 48 hours within 20 days, and calculate the water retention rate (WR) of the hydrogel according to the following formula: WR i = Wi / W0, where W i and W0 represent the weights of the hydrogel at times i and 0, respectively. At least three samples are tested to evaluate their water retention rates, and the final data is the average value.

[0102] The test results are as Figure 3 described: The hydrogel prepared in Example 1 can still maintain a water retention rate of about 88.42% by the 20th day as time goes by.

[0103] 4) Ion conductivity test

[0104] Test method: The electrochemical impedance method is used to test the ion conductivity of the hydrogel. A small-amplitude alternating current voltage with a frequency range of 0.1 Hz to 1 MHz is applied to the hydrogel electrolyte, and its impedance response at different frequencies is measured. An equivalent circuit model is established using the obtained Nyquist plot to separate the bulk resistance R b and the interfacial resistance. Then, in combination with the sample thickness (L) and the electrode area (A), according to the formula

[0105]

[0106] the ion conductivity is calculated, and the calculation results are shown in Table 2:

[0107] Table 2

[0108] Test item Ionic conductivity (mS / cm) Example 1 97.6 Example 2 92.7 Example 3 85.3 Comparative Example 1 34.3

[0109] After testing, compared with Comparative Example 1 lacking α-helical protein, the ion conductivity of the hydrogel prepared in Example 1 at room temperature is 97.6 mS / cm. The α-helical protein in the example can form a specific coordination interaction with the zinc ions of the zinc salt in the electrolyte, thus achieving ultra-high ion conductivity and having outstanding advantages in the existing hydrogel research result data.

[0110] At the same time, the test results of the mechanical tensile experiment show that the fracture strength of the prepared hydrogel is about 2.24 MPa, which is about 15 times that of the conventional polyvinyl alcohol electrolyte. The water retention test results at 25 °C room temperature also show its excellent water retention ability (still maintaining 88.42% after 20 days). And due to the use of biomass raw materials, this hydrogel exhibits degradable characteristics.

Claims

1. A hydrogel, characterized in that, The materials of the hydrogel include chitin, polyvinyl alcohol, and α-helical protein.

2. The hydrogel according to claim 1, wherein The mass ratio of the chitin, the polyvinyl alcohol, and the α-helical protein is (2-3):4:(1-2).

3. A method for preparing the hydrogel according to claim 1 or 2, characterized in that, The preparation steps include: S10. Mix chitin with a first solvent and perform freeze-thaw cycling operations to obtain a chitin solution. S20. Mix a protein product with a second solvent, concentrate and dialyze to obtain α-helical protein. S30. Prepare an aqueous solution of polyvinyl alcohol, and mix the aqueous solution of polyvinyl alcohol with the α-helical protein solution and the chitin solution, and stir to obtain a mixed solution. S40. Mix the mixed solution with a crosslinking agent to carry out a crosslinking reaction, freeze, and dry to obtain a hydrogel.

4. The method for preparing the hydrogel according to claim 3, wherein in step S10: the first solvent includes NaOH, urea, and water, and the mass ratio of the chitin to the first solvent is (4-6):100; and / or the concentration of chitin in the chitin solution is (4-6) wt%. in step S20: the second solvent includes urea, sodium dodecyl sulfate, and sodium sulfide, and the molar ratio of the urea, the sodium dodecyl sulfate, and the sodium sulfide is (60-100):1:1; and / or the protein product includes wool fibers; and / or the mixing of the wool fibers with the second solvent includes: adding 0.1-0.5 grams of the wool fibers per milliliter of the second solvent.

5. The preparation method of the hydrogel according to claim 3, characterized in that, Step S30 includes: S301. Mix polyvinyl alcohol and glycerol, and perform an oil bath to obtain an aqueous solution of polyvinyl alcohol. S302. Mix the aqueous solution of polyvinyl alcohol with the α-helical protein solution and the chitin solution, and stir to obtain a mixed solution.

6. The method for preparing the hydrogel according to claim 5, wherein in the polyvinyl alcohol solution, the concentration of the polyvinyl alcohol is 18-22 wt.%; and / or in the α-helical protein solution, the concentration of the α-helical protein is (4-6) wt%; and / or the volume ratio of the aqueous solution of polyvinyl alcohol to the α-helical protein solution and the chitin solution is 1:(1-2):(1-2).

7. The preparation method of the hydrogel according to claim 3, characterized in that, Step S40 includes: S401. Mix the mixed solution with a crosslinking agent to carry out a chemical crosslinking reaction to obtain a pre-crosslinked solution. S402. Mix the pre-crosslinked solution with hydrochloric acid to carry out physical crosslinking to obtain a gel solution. S403. Subject the gel solution to low-temperature treatment, freeze, and dry to obtain a hydrogel. wherein the crosslinking agent includes epichlorohydrin, and the mixing of the mixed solution with the crosslinking agent includes: adding 15-20 grams of the mixed solution per milliliter of epichlorohydrin.

8. A hydrogel electrolyte, characterized in that, The hydrogel electrolyte includes a hydrogel and an electrolyte salt, the electrolyte salt includes a zinc salt, and the hydrogel includes the hydrogel according to claim 1 or 2 or the hydrogel prepared by the method for preparing the hydrogel according to any one of claims 3-7.

9. A flexible battery, characterized in that, including the hydrogel electrolyte according to claim 8.

10. A wearable intelligent device, characterized in that, including the flexible battery according to claim 9.

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