A lysozyme amyloid fiber-based gel electrolyte and applications thereof

Abstract

The present application relates to the technical field of gel electrolyte for supercapacitor, in particular to a gel electrolyte based on lysozyme amyloid fibers and application thereof. The ion conductivity of the conventional plant protein-based gel electrolyte is poor, and the electrical performance needs to be further improved. In view of the above problems, the present application provides a gel electrolyte based on lysozyme amyloid fibers. The lysozyme in the formula self-assembles into amyloid fibers under acidic conditions, and the surface of the amyloid fibers is rich in polar groups such as hydroxyl, carboxyl and amino groups, which can effectively promote the dissociation of lithium salt. At the same time, the three-dimensional network structure formed by the self-assembly of the fibers. Glycerol as a small molecule plasticizer inserts between the polymer chains. Lithium perchlorate and other lithium salts can provide high concentration of free lithium ions due to the large anion volume and low dissociation energy. The above components synergize and jointly act, effectively improving the comprehensive electrical performance of the gel electrolyte.

Description

Technical Field

[0001] With the accelerated global energy transition, the large-scale application of renewable energy has created an urgent need for efficient energy storage technologies. Supercapacitors, as energy storage devices that combine high power density and long cycle life, have demonstrated irreplaceable advantages in electric vehicles, smart grids, and portable electronic devices. However, traditional supercapacitors rely on liquid electrolytes, which suffer from drawbacks such as easy leakage, strong corrosiveness, and poor safety, limiting their application, especially in extreme environments or scenarios with high safety requirements. Therefore, developing solid-state or gel electrolytes has become a key direction for improving the overall performance of supercapacitors.

[0002] Gel polymer electrolytes (GPEs), as a transitional form between liquid and solid electrolytes, combine a polymer matrix with lithium salts, plasticizers, etc., retaining the high ionic conductivity of liquid electrolytes while possessing the mechanical stability and safety of solid electrolytes. The choice of polymer matrix directly affects the ionic conductivity, mechanical strength, and interfacial compatibility of GPEs. Currently, commonly used polymer matrices such as polyethylene oxide (PEO) and polyvinylidene fluoride (PVDF), although commercially available, suffer from problems such as low ionic conductivity, high crystallinity, and high interfacial impedance with electrodes, making it difficult to meet the requirements of high-performance supercapacitors.

[0003] Biomass materials, due to their wide availability, environmental friendliness, and tunable structure, have gradually become a research hotspot for GPE (Geophysical Polymers) matrix materials. Among them, nanofiber structures formed by protein self-assembly have attracted much attention due to their unique physicochemical properties. Amyloid fibrils are a class of nanofibers formed by the self-assembly of proteins under specific conditions (such as acid, heat, and mechanical stirring). Their core structure is a cross-β-sheet conformation, composed of antiparallel β-sheets stacked through a hydrogen bond network. This structure endows amyloid fibrils with the following advantages:

[0004] High ion adsorption capacity: The abundant polar groups (such as hydroxyl, carboxyl, and amino groups) on the fiber surface can adsorb lithium ions through electrostatic interactions or coordination, promoting the dissociation of lithium salts;

[0005] Three-dimensional network structure: The self-assembled fiber network can provide continuous ion transport channels and reduce ion migration resistance;

[0006] Biocompatibility and biodegradability: In line with the development trend of green energy materials.

[0007] However, pure amyloid fibrous GPEs still suffer from insufficient mechanical strength and ionic conductivity limited by fiber density, necessitating modification strategies to optimize their performance. Existing research largely focuses on chemical crosslinking or physical blending modification, but the selection of crosslinking agents and the compatibility of blend components remain challenges.

[0008] Lysozyme, a basic globular protein widely found in organisms, possesses a well-defined amino acid sequence and a stable tertiary structure. Under acidic conditions (e.g., pH 3.8–4.2), lysozyme can partially unfold to expose hydrophobic regions, subsequently self-assembling to form amyloid protein fibers. Compared to plant-based protein fibers such as soybean protein, lysozyme fibers exhibit milder formation conditions (e.g., no need for high-concentration denaturants or extreme pH environments) and more uniform fiber morphology, which is beneficial for constructing ordered ion transport channels. Furthermore, the preparation of plant-based protein fibers such as soybean protein typically requires strong acid or alkali treatment, which may introduce impurities or damage the fiber structure, while lysozyme fibers offer higher biosafety and have potential applications in the interdisciplinary fields of biomedicine and energy.

[0009] To further enhance the overall performance of GPEs, the synergistic effect of plasticizers and crosslinking agents must be combined. Glycerin, as a small-molecule plasticizer, can insert into the polymer chains to reduce crystallinity and increase free volume, thereby improving ionic conductivity. Polyvinyl alcohol (PVA), due to its excellent film-forming properties and abundant hydroxyl groups, can serve as a blend matrix to enhance mechanical strength. Crosslinking agents such as acrylamide can form a three-dimensional network through chemical bonding, inhibiting polymer chain slippage and improving the dimensional stability of GPEs. The choice of lithium salt is equally crucial. Lithium salts such as lithium perchlorate (LiClO4) and lithium sulfate, due to their large anion volume and low dissociation energy, can provide a high concentration of free lithium ions, significantly improving ionic conductivity.

[0010] In summary, this invention proposes a gel electrolyte based on lysozyme-amyloid fibers. The fibers are formed through acid-thermal induced lysozyme self-assembly, plasticized by blending with glycerol and PVA, and chemically crosslinked with acrylamide, thus constructing a double-crosslinked GPE matrix with both high ionic conductivity and excellent mechanical strength. This approach overcomes the performance bottlenecks of traditional biomass-based GPEs and provides a new technical path for the development of high-performance supercapacitors. Summary of the Invention

[0011] A problem with existing technologies is that gel electrolytes based on conventional plant proteins have poor ionic conductivity, and their electrical properties need further improvement. To address this issue, this invention provides a gel electrolyte based on lysozyme-amyloid cellulose, the preparation method of which includes the following steps:

[0012] (1) Dissolve lysozyme in ultrapure water, adjust the solution to be acidic, and heat and stir continuously at 85-95℃ to obtain amyloid protein fiber solution;

[0013] (2) Add glycerol and polyvinyl alcohol to the amyloid protein fiber solution, heat and stir continuously at 85-95℃ until homogeneous, then cool the reaction system to room temperature and add acrylamide and crosslinking agent to the reaction system, stir until homogeneous at room temperature to obtain a mixture;

[0014] (3) Add lithium salt and photoinitiator to the mixture, stir evenly, pour into a mold, and irradiate with ultraviolet light to obtain gel electrolyte.

[0015] Preferably, the mass concentration of lysozyme in ultrapure water in step (1) is 1-3%.

[0016] Preferably, the pH of the solution in step (1) is 3.8-4.2.

[0017] Preferably, in step (2), the mass ratio of glycerol to lysozyme is (37-40):(0.5-1), and the mass ratio of glycerol to polyvinyl alcohol is (37-40):(13-18).

[0018] Preferably, in step (2), the polyvinyl alcohol is at least one of PVA 1788, PVA 2488 and PVA 2088.

[0019] Preferably, the mass ratio of acrylamide to lysozyme is (100-130):(0.5-1), the crosslinking agent is N,N'-methylenebisacrylamide, and the mass ratio of crosslinking agent to lysozyme is (0.15-0.2):(0.4-0.6).

[0020] Preferably, the lithium salt in step (3) is at least one of lithium perchlorate, lithium sulfate, lithium chloride, and lithium nitrate.

[0021] Preferably, the concentration of lithium salt in the mixture is 1-5 mol / L. -1 .

[0022] Preferably, the mass ratio of photoinitiator to lysozyme is (0.9-1.1):(0.9-1.1).

[0023] The gel electrolyte based on lysozyme amyloid fibrous protein provided by this invention addresses the problems of poor ionic conductivity and insufficient electrical performance of gel electrolytes based on conventional plant proteins in existing technologies. Through unique raw material selection and preparation process, it achieves multi-faceted performance optimization, providing a new and effective technical path for the development of high-performance supercapacitors. The specific beneficial effects are as follows:

[0024] (1) High ionic conductivity: The amyloid protein fibers formed by the self-assembly of lysozyme under acidic conditions are rich in polar groups such as hydroxyl, carboxyl, and amino groups on their surface. These groups can effectively adsorb lithium ions through electrostatic interactions or coordination, promoting the dissociation of lithium salts and providing abundant active sites for ion transport. At the same time, the three-dimensional network structure formed by the self-assembly of fibers provides continuous transport channels for ions and reduces the resistance to ion migration. In addition, glycerol, as a small molecule plasticizer, is inserted between polymer chains, reducing crystallinity and increasing free volume, further improving ionic conductivity. Lithium salts such as lithium perchlorate, due to their large anion volume and low dissociation energy, can provide a high concentration of free lithium ions, significantly enhancing ionic conductivity and thus effectively improving the electrical properties of the gel electrolyte.

[0025] (2) Excellent mechanical strength: Polyvinyl alcohol (PVA) has good film-forming properties and its molecular chains are rich in hydroxyl groups. When it is blended with amyloid cellulose solution, the PVA molecular chains and fibers intertwine, enhancing the cohesive force of the material and effectively improving the mechanical strength of the gel electrolyte. At the same time, acrylamide, as a crosslinking agent, forms a three-dimensional network structure through chemical bonding, inhibiting polymer chain slippage and further improving the dimensional stability and mechanical strength of the gel electrolyte, enabling it to better adapt to various mechanical environments in practical applications.

[0026] (3) Mild preparation conditions: Compared with plant-based protein fibers such as soybean protein, lysozyme fibers have milder formation conditions. Under acidic conditions (e.g., pH=3.8-4.2), lysozyme can self-assemble into fibers by partially unfolding to expose hydrophobic regions, without the need for high concentrations of denaturants or extreme pH environments. This not only simplifies the preparation process and reduces production costs, but also reduces impurities that may be introduced by strong acid or strong alkali treatment and the damage to the fiber structure, ensuring the quality and performance of the fiber.

[0027] (4) Performance Breakthrough and Technological Innovation: This invention constructs a double-crosslinked GPE matrix with both high ionic conductivity and excellent mechanical strength by acid-heat-induced lysozyme self-assembly to form fibers, compounding glycerol with PVA for plasticization, and combining it with acrylamide chemical crosslinking. This approach breaks through the performance bottleneck of traditional biomass-based GPEs, providing new technical ideas and methods for the development of high-performance supercapacitors, and is conducive to promoting the further development and application of gel electrolyte technology. Attached Figure Description

[0028] Figure 1 Flowchart of the preparation process of gel electrolyte based on lysozyme amyloid protein fibers in Example 1.

[0029] Figure 2 : The bonding effect of the gel electrolyte obtained in Example 1.

[0030] Figure 3 AFM diagram of the gel electrolyte obtained in Example 1.

[0031] Figure 4 SEM image of the gel electrolyte obtained in Example 1.

[0032] Figure 5 The results of compressive strength tests conducted on square gel electrolytes of identical size obtained in Examples 1, 1, and 2 on a universal testing machine at a loading speed of 10 mm / min.

[0033] Figure 6 The results of tensile tests conducted on square gel electrolytes of identical size obtained in Example 1, Comparative Example 1, and Comparative Example 2 at a loading speed of 10 mm / min on a universal testing machine.

[0034] Figure 7 : Schematic diagram of the connection structure of the self-assembled flexible supercapacitor used for electrical performance testing of the present invention.

[0035] Figure 8 The room temperature impedance of the gel electrolyte was tested by electrochemical impedance spectroscopy (EIS) on the flexible supercapacitors obtained in Examples 1, 1, and 2.

[0036] Figure 9 The electrochemical impedance spectroscopy (EIS) was used to test the ionic conductivity of the gel electrolyte at different temperatures in the flexible supercapacitors obtained in Examples 1, 1, and 2.

[0037] Figure 10 Examples 1, 1 (Comparative Example), and 2 (Comparative Example) are flexible supercapacitors. Their electrical performance was tested under the same conditions, specifically at 0.5 mA / cm². 2 Under the given current conditions, the charge-discharge performance of the flexible gel electrolyte was tested using constant current charge-discharge (GCD).

[0038] Figure 11 Examples 1, 1 (Comparative Example), and 2 (Comparative Example) are flexible supercapacitors. Their electrical performance was tested under the same conditions, specifically at 0.5 mA / cm². 2 Under the given current conditions, the specific capacitance of the flexible gel electrolyte was tested using constant current charge-discharge (GCD).

[0039] Figure 12 The results of cyclic voltammetry testing of the square gel electrolyte obtained in Example 1, which was pressed together with two carbon electrodes of the same size and electrically connected by wires to form a flexible supercapacitor.

[0040] Figure 13The constant current charge-discharge test results of the square gel electrolyte obtained in Example 1, which was pressed together with two carbon electrodes of the same size and electrically connected by wires to form a flexible supercapacitor.

[0041] Figure 14 In Example 1, the square gel electrolyte was bent at 0°, 90°, and 180° and pressed against two carbon electrodes of identical size, then electrically connected by wires to form a flexible supercapacitor. The supercapacitor was tested at a scan rate of 20 mV / s. -1 Cyclic voltammetry curves under potential range of 0.0–1.0 V.

[0042] Figure 15 In Example 1, the square gel electrolyte was bent at 0°, 90°, and 180° and pressed against two carbon electrodes of identical size, then electrically connected by wires to form a flexible supercapacitor. The supercapacitor was tested at a scan rate of 20 mV / s. -1 The constant current charge-discharge curves under the condition of potential range 0.0–1.0 V.

[0043] Figure 16 The charge-discharge cycle stability of flexible supercapacitors assembled from the flexible superelectrolytes obtained in Example 1, Comparative Example 1, and Comparative Example 2 under the same test conditions. Detailed Implementation

[0044] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are merely illustrative examples of implementation of the present invention and are not intended to limit the scope of the present invention.

[0045] The lysozyme used in this invention is from Davisco International Foods, catalog number JE 003-6-922.

[0046] The conventional gel electrolyte used in this invention, commercially known as acrylamide-potassium hydroxide flexible electrolyte, is prepared as follows:

[0047] 15 g of acrylamide was dissolved in 100 mL of deionized water. 0.12 g of N,N'-methylenebisacrylamide was added as a crosslinking agent and 0.045 g of α-ketoglutaric acid. The mixture was then cast into a film and polymerized under UV initiation to obtain a polyacrylamide gel membrane. Subsequently, the gel membrane was immersed in a 6 mol / L potassium hydroxide aqueous solution for 2 h to allow the electrolyte to be fully adsorbed and enter the gel network. After removal, the membrane was first vertically suspended for 20 s to remove naturally dripping liquid. Then, the free liquid on the membrane surface was gently absorbed with filter paper to avoid squeezing the electrolyte inside the gel, thus obtaining a flexible gel electrolyte.

[0048] The carbon electrode used in this invention is prepared by the following method:

[0049] (1) Activated carbon, conductive carbon black and polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 80:10:10. Based on a total solid content of 1.0 g per batch, the mixture contains 0.80 g of activated carbon, 0.10 g of conductive carbon black and 0.10 g of PVDF. N-methylpyrrolidone (NMP) is added as a solvent and stirred to obtain a uniform slurry with a solid content of approximately 10.8 wt%.

[0050] (2) The slurry was uniformly coated on both sides of the pretreated 2cm×2cm nickel foam current collector, dried at 80℃ for 12h, and then pressed into a sheet to obtain the carbon electrode. The surface active material loading of the carbon electrode was 3.0 mg / cm³. 2 The nickel foam current collector was purchased from TOB NEW ENERGY, specifically nickel foam sheets (model TOB-NF03). Its typical technical parameters are: thickness 1.0 mm, porosity 97%, purity ≥99.8%, pore size grade 110 PPI, and areal density 350 ± 20 g / m³. 2 .

[0051] Example 1

[0052] A gel electrolyte based on lysozyme amyloid fibrous protein, preparation method (process flow diagram is attached to the instruction manual). Figure 1 As shown below:

[0053] (1) First, weigh 0.6g of lysozyme and dissolve it in 29.4g of ultrapure water. Then, slowly add 1M HCl aqueous solution to the solution to adjust the pH of the solution to 4. Then, put the solution into an oil bath and stir continuously at 90℃ for 24 hours to allow it to react fully and obtain amyloid protein fiber solution.

[0054] (2) Add 30 mL of glycerol and 15 g of PVA1788 to the amyloid cellulose solution obtained in step (1), keep at 90 °C and stir continuously for 1 h, then lower the temperature of the reaction system to room temperature, and then add 120 g of acrylamide and 9 mL of N,N'-methylenebisacrylamide aqueous solution with a mass fraction of 2% to the reaction system, and stir continuously at room temperature for 2 h to obtain a mixture;

[0055] (3) Add LiClO4 and 0.6g of photoinitiator α-ketoglutarate to the mixture obtained in step (2), stir evenly, and the concentration of LiClO4 in the solution is 3M. ​​Then pour the solution into a mold and irradiate it under a 365 nm ultraviolet lamp for 2 hours to obtain the gel electrolyte.

[0056] The gel electrolyte obtained in Example 1 was placed horizontally on a table, measuring 1cm × 1cm × 7mm. A 150g titanium dioxide tube was then bonded to it, and it adhered firmly without falling off. The bonding effect is shown in the attached instruction manual. Figure 2 As shown, the gel electrolyte obtained in Example 1 of this invention has good bonding properties and can be tightly bonded to the electrode.

[0057] The gel electrolyte obtained in Example 1, as imaged by atomic force microscopy and transmission electron microscopy, exhibits a helical structure with an average diameter of 30 nanometers. During the preparation of the gel electrolyte, polyvinyl alcohol in the gel electrolyte causes amyloid protein fibers to aggregate and form clusters, constructing the first physical cross-linked network of the hydrogel. Acrylamide, through ultraviolet light polymerization, constructs an elastic channel structure, forming a chemically cross-linked elastic network of the hydrogel. Glycerol can act as a bridging cross-linking agent in the hydrogel network, enhancing the physical cross-linking between the hydrogel networks. The AFM and SEM images of the gel electrolyte obtained in Example 1 are attached to the instruction manual. Figure 3 and Figure 4 As shown, this hybrid physicochemical cross-linking network creates a porous and dense microstructure in the hydrogel.

[0058] Comparative Example 1

[0059] A gel electrolyte, prepared by the following method:

[0060] (1) Add 30 mL of glycerol and 15 g of PVA1788 to 29.4 g of ultrapure water, keep at 90 °C and stir continuously for 1 h. Then lower the temperature of the reaction system to room temperature, and then add 120 g of acrylamide and 9 mL of N,N'-methylenebisacrylamide aqueous solution with a mass fraction of 2% to the reaction system. Stir continuously at room temperature for 2 h to obtain a mixture.

[0061] (3) Add LiClO4 and 0.6g of photoinitiator α-ketoglutarate to the mixture obtained in step (1), stir evenly, and the concentration of LiClO4 in the solution is 3M. ​​Then pour the solution into a mold and irradiate it under a 365 nm ultraviolet lamp for 2 hours to obtain the gel electrolyte.

[0062] Comparative Example 2 uses a conventional gel electrolyte.

[0063] Square gel electrolytes of identical size (both upper and lower surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained from Example 1, Comparative Example 1, and Comparative Example 2 were subjected to compressive and tensile tests on a universal testing machine at a loading speed of 10 mm / min. The test results are shown in the appendix to the instruction manual. Figure 5 , 6As shown in the figure. The test results show that, under the same compressive strain conditions, the gel electrolyte obtained in Example 1 of this invention reaches 0.8 MPa when compressed to 50% strain, consistently exhibiting higher compressive stress, indicating that its compressive strength and structural stability are superior. The compressive performance of the gel obtained in Comparative Example 1 is second best, while the conventional gel electrolyte has the lowest compressive stress, indicating that its internal network load-bearing capacity is weak and it is more prone to deformation under external forces. Especially in the medium-to-high strain region, the stress growth of the gel electrolyte obtained in Example 1 of this invention is faster, showing more obvious strain hardening characteristics, indicating that the introduction of amyloid protein fibers effectively enhances the internal network effect of the gel and improves the material's resistance to deformation under compressive conditions.

[0064] During the stretching process, the gel electrolyte obtained in Example 1 of this invention exhibited the highest tensile stress and the largest elongation at break, with tensile stress and deformation of approximately 0.9 MPa and 700%, respectively, significantly better than Comparative Example 1 and Comparative Example 2. In contrast, the tensile strength and fracture strain of the gel electrolyte obtained in Comparative Example 1 decreased significantly, indicating that the removal of amyloid fibers reduced the effective physical cross-linking and energy dissipation units in the gel network, leading to a weakening of load transfer capacity and fracture resistance. The conventional gel electrolyte in Comparative Example 2 exhibited even lower tensile strength and worse ductility, indicating insufficient toughness and difficulty in meeting the service requirements of repeated bending and stretching of flexible devices. More importantly, the gel electrolyte obtained in Example 1 of this invention maintained good integrity even after reaching a large deformation and returned to its original shape after unloading, indicating that the gel possesses both high strength, good flexibility, and excellent elastic recovery performance.

[0065] The square-shaped gel electrolyte (both top and bottom surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained in Example 1 was subjected to pull-out and peel tests on a universal testing machine at a constant tensile speed of 10 mm / min. The calculated adhesion strength between the gel and the substrate (the substrate is a carbon electrode) was 5 MPa. This hydrogel exhibits excellent adhesion to the electrode, indicating great potential for applications in flexible supercapacitors.

[0066] Square gel electrolytes of the same size (both upper and lower surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained in Example 1, Comparative Example 1, and Comparative Example 2 are pressed together with two carbon electrodes of the same size and electrically connected by wires to form a flexible supercapacitor (connection structure as shown in the attached instruction manual). Figure 7 (As shown). The room-temperature ionic conductivity of the gel electrolyte was tested by electrochemical impedance spectroscopy (EIS) for the flexible supercapacitors obtained in Example 1, Comparative Example 1, and Comparative Example 2, respectively. The test results are shown in the appendix to the instruction manual. Figure 8 As shown.

[0067] Depend on Figure 8 It can be seen that the gel electrolyte obtained in Example 1 of this invention has an intercept of approximately 1.01 Ω with respect to the real axis in the high-frequency region, indicating that its equivalent series internal resistance is small and the overall impedance of the device is low. Simultaneously, the curve in the low-frequency region is nearly vertical, indicating that it has ideal capacitive behavior and fast ion transport kinetics. In contrast, the impedance curve of the gel electrolyte obtained in Comparative Example 1 shifts to the right overall, with an increased high-frequency intercept, indicating that both its ohmic internal resistance and interfacial impedance have increased. The impedance curve of the conventional gel electrolyte in Comparative Example 2 shifts further to the right, exhibiting greater internal resistance and poorer ion transport capability. Therefore, the impedance of the three devices, from smallest to largest, is: Example 1 < Comparative Example 1 < Comparative Example 2. This demonstrates that the introduction of lysozyme amyloid fibers can effectively reduce the internal resistance of the device, improve the electrode-electrolyte interface contact, and enhance the ionic conductivity of the gel electrolyte, resulting in superior electrochemical performance.

[0068] Square gel electrolytes of the same size (both upper and lower surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained in Examples 1, 1, and 2 were pressed together with two carbon electrodes of identical size and electrically connected by wires to form flexible supercapacitors. The ionic conductivity of the gel electrolytes at different temperatures was tested using electrochemical impedance spectroscopy (EIS) on the flexible supercapacitors obtained in Examples 1, 1, and 2, respectively. The test results are shown in the appendix to the instruction manual. Figure 9 As shown.

[0069] Figure 9 The results show that the gel electrolyte obtained in Example 1 consistently exhibits the highest conductivity under the same test conditions, reaching 311.9 mS / cm.

[0070] The conductivity values ​​of Example 1, Comparative Example 2, and Comparative Example 3 were 173.3 mS / cm, 69.3 mS / cm, and 173.3 mS / cm, respectively. Comparative Example 1 was next, with values ​​of 57.8 mS / cm, 36.1 mS / cm, and 7.9 mS / cm, respectively. Comparative Example 2 had the lowest conductivity, at only 11.2 mS / cm, 8 mS / cm, and 1.1 mS / cm. The overall ionic conductivity, from highest to lowest, was: Example 1 > Comparative Example 1 > Comparative Example 2. This result indicates that the introduction of lysozyme amyloid fibers significantly improved the ion transport capacity within the gel, enabling the gel to maintain higher conductivity under different testing conditions. In contrast, although the gel electrolyte obtained in Comparative Example 1 still possessed some ion-conducting capacity, its conductivity decreased significantly due to the lack of optimization of the network structure and ion migration channels by lysozyme amyloid fibers. The commercially available gel had the lowest conductivity, indicating poor ion transport efficiency and structural stability. Meanwhile, the trends in the three sets of data also show that as the testing conditions became more stringent, the conductivity of all three gel electrolytes decreased. However, the gel electrolyte obtained in Example 1 still maintained a significant advantage, indicating that it has better environmental adaptability and more stable ion transport performance. In summary, the addition of amyloid fibers can not only reduce device impedance but also significantly improve the ion conductivity of the gel electrolyte, thereby contributing to the improvement of the electrochemical performance of flexible supercapacitors.

[0071] Square gel electrolytes of the same size (both upper and lower surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained in Example 1, Comparative Example 1, and Comparative Example 2 were pressed together with two carbon electrodes of identical size and electrically connected by wires to form flexible supercapacitors. Electrical performance tests were conducted under the same conditions, specifically at 0.5 mA / cm². 2 Under the specified current conditions, the electrochemical performance of the flexible gel electrolyte was tested using constant current charge-discharge (GCD). The test results are shown in the appendix to the instruction manual. Figure 10 , 11 As shown.

[0072] Depend on Figure 10As can be seen, the charge-discharge curves of the flexible supercapacitors are approximately symmetrical triangles, indicating that all three types of flexible supercapacitors possess good reversible charge-discharge characteristics and capacitive behavior. Among them, the flexible supercapacitor with the gel electrolyte obtained in Example 1 has the longest charge-discharge time, followed by the one with the gel electrolyte obtained in Comparative Example 1, and the one with the gel electrolyte in Comparative Example 2 has the shortest. This indicates that the introduction of amyloid fibers can effectively improve the ion transport capacity of the gel electrolyte and the electrode-electrolyte interface matching, thereby enhancing the energy storage capacity of the device. Meanwhile, the discharge time of the flexible supercapacitor with the gel electrolyte obtained in Example 1 is significantly prolonged, indicating that it can release more charge at the same current density, exhibiting a higher specific capacitance. Although the flexible supercapacitor with the gel electrolyte obtained in Comparative Example 1 still possesses some energy storage performance, it is significantly lower than that of Example 1. The flexible supercapacitor with the gel electrolyte in Comparative Example 2 has the shortest discharge time, indicating that its charge storage capacity and electrochemical performance are the weakest. In summary, the results show that the gel electrolyte obtained in Example 1 of this invention can significantly improve the charge-discharge performance of flexible supercapacitors and endow the device with superior energy storage characteristics.

[0073] In addition, the specific capacitance of three flexible supercapacitors under different discharge current densities was tested under the same test conditions, and the results are as follows: Figure 11 As shown, the specific capacitance of all three capacitors decreased with increasing discharge current density. This is because at higher current densities, the diffusion time of ions at the electrode-electrolyte interface and inside the electrode is shortened, and the active sites cannot be fully utilized, resulting in a decrease in specific capacitance. Among them, the flexible supercapacitor corresponding to the gel electrolyte obtained in Example 1 consistently exhibited the highest specific capacitance at all discharge current densities, followed by Comparative Example 1, and the lowest in Comparative Example 2. This indicates that the introduction of amyloid protein fibers can significantly improve the ion transport performance and interfacial energy storage capacity of the gel electrolyte, enabling the device to maintain a high charge storage capacity under different rate conditions. Compared with the other two groups, the flexible supercapacitor corresponding to the gel electrolyte obtained in Example 1 can still maintain a high specific capacitance at high current densities, indicating that it has superior rate performance and faster electrochemical response. Meanwhile, it can be seen that the specific capacitance of the flexible supercapacitor corresponding to the gel electrolyte obtained in Example 1 decreases relatively little with increasing current density, indicating that it can still effectively maintain its energy storage performance under rapid charge and discharge conditions. In contrast, the specific capacitance of the capacitors corresponding to Comparative Examples 1 and 2 decreases more significantly, indicating that their ion diffusion and interfacial transport processes are more affected by current density, resulting in poorer rate performance. In summary, the results show that the gel electrolyte obtained in Example 1 of this invention enables the flexible supercapacitor to not only have a high specific capacitance but also exhibit superior rate performance under different discharge current densities, better meeting the application requirements of flexible supercapacitors under high power output conditions.

[0074] The square gel electrolyte (both top and bottom surfaces are square, each with a side length of 2 cm and a thickness of 7 mm) obtained in Example 1 was pressed together with two carbon electrodes of identical size and electrically connected by wires to form a flexible supercapacitor. The electrochemical performance of the flexible gel electrolyte was tested using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The test results are as follows: Figure 12 , 13 As shown, the cyclic voltammetry curves maintained a nearly rectangular shape at different scan rates ranging from 10 to 100 mV s⁻¹, indicating that the device primarily exhibits typical double-layer capacitance behavior and maintains good rate performance even at higher scan rates. The in-situ electrochemical depolarization (constant current charge-discharge) curves obtained at different current densities ranging from 0.05 to 0.5 A g⁻¹ exhibited a nearly symmetrical triangular shape, demonstrating that the supercapacitor possesses a highly reversible charge-discharge process and excellent coulombic efficiency.

[0075] Three identical square gel electrolytes obtained in Example 1 (both top and bottom surfaces are square, each with a side length of 2cm and a thickness of 7mm) were bent to 0°, 90°, and 180° respectively, pressed tightly against two identical carbon electrodes, and electrically connected by wires to form flexible supercapacitors. The scanning speed was 20 mV / s. -1 The capacitance change curves were tested under the condition of a potential range of 0.0–1.0 V, and the resulting cyclic voltammetry curves are shown in the figure. Figure 14 , 15 As shown.

[0076] The three closed curves corresponding to the supercapacitor at 0° (straight), 90° (right-angle bend), and 180° (fold) show the CV response under three mechanical states. These three curves are all roughly rectangular and almost completely overlap, indicating that bending deformation has minimal impact on capacitive behavior. This fully demonstrates that the amyloid protein-based flexible supercapacitor gel electrolyte material prepared in this invention possesses excellent mechanical stability and flexible reliability. Even when bent to 180°, the device's capacitance characteristics, interfacial contact, and ion transport do not degrade, verifying the compatibility between the electrolyte and the electrode, making it suitable for repeated deformation scenarios in wearable devices.

[0077] The flexible superelectrolytes obtained in Example 1, Comparative Example 1, and Comparative Example 2 were cut into square gel electrolytes with square top and bottom surfaces, each square having a side length of 2 cm and a thickness of 3 mm. Two carbon electrodes of the same size as the gel electrolyte were attached to both sides of the gel electrolyte and pressed together to form a flexible supercapacitor. The carbon electrode plates of an electrochemical workstation (model: CHI760F) were clamped at both ends of the capacitor, and the specific capacitance retention rate of the capacitor was calculated after 5000 cycles. The test parameters were: anode and cathode currents of 2 mA, voltage window of 0-1.0 V, sampling interval of 0.8 s, and 5000 cycles. The test results were compared with those of a conventional gel electrolyte as a control. Figure 16 As shown.

[0078] from Figure 16 The cycle retention curves show significant differences in the stability of the three capacitors during long-term cycling. The capacitor corresponding to Comparative Example 2 exhibits some degradation in the initial stage, with its specific capacitance retention gradually decreasing from approximately 100% and stabilizing at around 95%, remaining near this level even after 5000 cycles. This indicates acceptable cycle stability, but significant early capacitance loss. The capacitor corresponding to Comparative Example 1 shows a slight electrochemical activation process, with its specific capacitance retention slowly increasing from an initial 100%, reaching approximately 103–104% after about 1000–2000 cycles. It then slightly decreases, remaining at around 102% after 5000 cycles. This indicates that its cycling performance is superior to commercially available gels, but its activation level and long-term retention capacity are still significantly lower than those of the capacitor corresponding to Example 1. In contrast, the capacitor corresponding to Example 1 exhibited more significant electrochemical activation behavior in the early stage, with the specific capacitance retention rapidly increasing to approximately 132–133%, followed by a slow decline, and remaining at around 130% after 5000 cycles. This result indicates that the introduction of amyloid fibers continuously improves the wetting and contact state of the electrode / electrolyte interface during cycling, promoting the gradual and full opening of ion transport channels, thereby enabling the effective utilization of more active sites. This demonstrates significantly better cycling stability and energy storage activation characteristics than the capacitors corresponding to Comparative Examples 1 and 2, respectively. Overall, the cycling performance of the three capacitors follows the order: Example 1 > Comparative Example 1 > Comparative Example 2. This suggests that the introduction of amyloid fibers not only improves the initial electrochemical performance of the device but also effectively suppresses capacity decay during long-term cycling, enhances electrode / electrolyte interface stability and structural durability, thus endowing the flexible supercapacitor with superior cycle life and long-term operational reliability.

[0079] Comparative Example 3

[0080] A gel electrolyte based on lysozyme amyloid fibrous protein is prepared as follows:

[0081] (1) First, weigh 0.6g of soybean protein and evenly disperse it into 29.4g of ultrapure water to obtain soybean protein solution;

[0082] (2) Add 30 mL of glycerol and 15 g of PVA1788 to the soybean protein solution obtained in step (1), keep at 90 °C and stir continuously for 1 h, then lower the temperature of the reaction system to room temperature, and then add 120 g of acrylamide and 9 mL of N,N'-methylenebisacrylamide aqueous solution with a mass fraction of 2% to the reaction system, and stir continuously at room temperature for 2 h to obtain a mixture;

[0083] (3) Add LiClO4 and 0.6g of photoinitiator α-ketoglutarate to the mixture obtained in step (2), stir evenly, and the concentration of LiClO4 in the solution is 3M. ​​Then pour the solution into a mold and irradiate it under a 365 nm ultraviolet lamp for 2 hours to obtain the gel electrolyte.

[0084] Comparative Example 4 is the same as Example 1, except that no glycerin was added in Comparative Example 4.

[0085] Comparative Example 5 is the same as Example 1, except that polyvinyl alcohol was not added in Comparative Example 5.

[0086] Comparative Example 6 is the same as Example 1, except that the mass of PVA1788 in Comparative Example 6 is 5g.

[0087] Comparative Example 7 is the same as Example 1, except that the mass of PVA1788 in Comparative Example 7 is 20g.

[0088] Comparative Example 8 is the same as Example 1, except that the amount of glycerol added in Comparative Example 8 is 5 mL.

[0089] Comparative Example 9 is the same as Example 1, except that the amount of glycerol added in Comparative Example 9 is 50 mL.

[0090] Performance testing:

[0091] Compressive strength at 50% strain: Tensile test was conducted on a universal testing machine at a loading rate of 10 mm / min.

[0092] Tensile strength with 700% deformation: Tensile test was conducted on a universal testing machine at a loading rate of 10 mm / min.

[0093] Adhesion strength: Pull-off and peel tests were conducted on a universal testing machine at a constant tensile speed of 10 mm / min, and the adhesion strength between it and the substrate (the substrate is a carbon electrode) was calculated.

[0094] Resistance: The flexible supercapacitors of each comparison were tested using electrochemical impedance spectroscopy (EIS) to obtain Nyquist impedance spectra. The intercept of the high-frequency region curve with the real axis was taken as the equivalent series resistance (ESR) or ohmic internal resistance of the device, in Ω. Ionic conductivity: The bulk resistance of the gel electrolyte was obtained by EIS testing, and the ionic conductivity was calculated using the formula σ=L / (Rb×S), where L is the gel thickness, S is the effective contact area, and S is the resistance corresponding to the high-frequency intercept.

[0095] Specific capacitance:

[0096] The test was conducted using the constant current charge-discharge method (GCD) at 0.5 mA / cm². 2 At current density, according to the discharge curve, use formula C A = IΔt / (SΔV) Calculate the area-to-capacitance ratio. Where C A The areal capacitance is (F / cm² or mF / cm²), I is the discharge current (A), Δt is the discharge time (s), and S is the effective electrode area (cm²). 2 ), ΔV is the effective discharge voltage window (V) after deducting IR drop.

[0097] The test results are shown in Table 1:

[0098] Table 1

[0099] Test Items Compressive strength (MPa) at 50% strain Tensile strength (MPa) at 700% deformation Adhesion force (MPa) Resistance (Ω) Ionic conductivity (mS / cm) <![CDATA[Specific capacitance (mF / cm 2 )]]> Example 1 0.8 0.9 5 1.01 173.3 0.679 Comparative Example 3 0.62 0.68 3.9 1.36 141.8 0.552 Comparative Example 4 0.58 0.42 3.1 1.72 112.6 0.471 Comparative Example 5 0.41 0.36 2.4 1.89 105.4 0.438 Comparative Example 6 0.56 0.61 3.5 1.48 132.7 0.516 Comparative Example 7 0.84 0.73 4.6 1.29 149.5 0.593 Comparative Example 8 0.64 0.55 3.6 1.55 126.9 0.503 Comparative Example 9 0.52 0.63 4.1 1.22 158.2 0.571

[0100] Compared to Example 1, in Comparative Example 3, replacing lysozyme with soybean protein resulted in a reduction in continuous ion transport channels within the gel due to the difficulty in forming a uniform and ordered amyloid fibrous network. This led to increased impedance, decreased ionic conductivity, and consequently, reduced specific capacitance, rate performance, and cycling stability. In Comparative Examples 4 and 8, the reduction or absence of glycerol resulted in insufficient plasticizing effect, reduced free volume, and restricted chain segment movement, leading to decreased ion migration capacity, as well as poorer flexibility and adhesion. In Comparative Examples 5 and 6, the reduction or absence of PVA resulted in insufficient physical cross-linking network of the gel, decreased film-forming properties and cohesion, and reduced material compressibility, tensile properties, and interfacial stability. In Comparative Example 7, the excessive amount of PVA resulted in an overly dense system, increasing ion migration resistance and negatively impacting conductivity and rate performance. In Comparative Example 9, the excessive amount of glycerol led to over-plasticization of the gel network, reducing mechanical strength and dimensional stability, thus affecting the long-term cycling stability of the device. The above results indicate that there is a significant synergistic effect among lysozyme amyloid fibrils, PVA, and glycerol, and that the proportions of each group are within an appropriate range, with Example 1 exhibiting the best overall performance.

[0101] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A gel electrolyte based on lysozyme amyloid fibrous protein, characterized in that, The preparation method includes the following steps: (1) Dissolve lysozyme in ultrapure water, adjust the solution to be acidic, and heat and stir continuously at 85-95℃ to obtain amyloid protein fiber solution; (2) Add glycerol and polyvinyl alcohol to the amyloid protein fiber solution, heat and stir continuously at 85-95℃ until homogeneous, then cool the reaction system to room temperature and add acrylamide and crosslinking agent to the reaction system, stir until homogeneous at room temperature to obtain a mixture; (3) Add lithium salt and photoinitiator to the mixture, stir evenly, pour into a mold, and irradiate with ultraviolet light to obtain gel electrolyte.

2. The gel electrolyte based on lysozyme amyloid fibrous protein according to claim 1, characterized in that, In step (1), the mass concentration of lysozyme in ultrapure water is 1-3%.

3. The gel electrolyte based on lysozyme amyloid fibrous protein according to claim 1, characterized in that, The pH of the solution in step (1) is 3.8-4.

2.

4. The gel electrolyte based on lysozyme amyloid fibrous protein according to claim 1, characterized in that, In step (2), the mass ratio of glycerol to lysozyme is (37-40):(0.5-1), and the mass ratio of glycerol to polyvinyl alcohol is (37-40):(13-18).

5. A gel electrolyte based on lysozyme amyloid fibers according to claim 4, characterized in that, In step (2), the polyvinyl alcohol is at least one of PVA 1788, PVA 2488 and PVA 2088.

6. The gel electrolyte based on lysozyme amyloid fibrous protein according to claim 1, characterized in that, The mass ratio of acrylamide to lysozyme is (100-130):(0.5-1), the cross-linking agent is N,N'-methylenebisacrylamide, and the mass ratio of cross-linking agent to lysozyme is (0.15-0.2):(0.4-0.6).

7. The gel electrolyte based on lysozyme amyloid fibrous protein according to claim 1, characterized in that, The lithium salt in step (3) is at least one of lithium perchlorate, lithium sulfate, lithium chloride, and lithium nitrate.

8. The gel electrolyte based on lysozyme amyloid fibers according to claim 7, characterized in that, The concentration of lithium salt in the mixture is 1-5 mol / L. -1 .

9. A gel electrolyte based on lysozyme amyloid fibers according to claim 1, characterized in that, The mass ratio of photoinitiator to lysozyme is (0.9-1.1):(0.9-1.1).

10. A supercapacitor, characterized in that, The gel electrolyte according to any one of claims 1-9 is used as its electrolyte.

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