Biomass-based solid electrolyte as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electrochemical energy storage, and discloses a biomass-based solid electrolyte and a preparation method and application thereof, and the biomass-based solid electrolyte comprises the following chemical components in percentage by mass: 9.0%-21.4% of polyvinyl alcohol, 2.9%-12.7% of sodium alginate, 1.5%-6.5% of sodium chloride, 1.4%-8.9% of borax, 0.3%-1.5% of graphene and the balance of deionized water. According to the preparation method, the sodium alginate and the polyvinyl alcohol form the interpenetrating double-network hydrogel through hydrogen bonds, the graphene is introduced into the hydrogel, and the electrochemical performance and the mechanical performance of the biomass-based solid electrolyte prepared by the preparation method disclosed by the invention are greatly improved by adopting a microfluidic technology and an ionic crosslinking method under low salt concentration.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical energy storage technology, specifically relating to a biomass-based solid electrolyte, its preparation method, and its application. Background Technology

[0002] With the increasing global demand for clean energy and efficient energy storage technologies, the market for new energy vehicles is expanding rapidly, and battery packs are a core technology in these vehicles. Supercapacitors, due to their high power density, rapid charging and discharging, and long cycle life, have broad application prospects in the auxiliary power systems, energy recovery systems, and applications requiring rapid charging and discharging (such as smart grids and pulse power supplies) of electric vehicles. As an auxiliary energy source for secondary batteries (such as lithium-ion batteries), they can be used in conjunction with secondary batteries to form a stable, energy-efficient, and environmentally friendly power source for automobiles. In this process, the secondary battery is mainly responsible for solving the problems of charging and storing energy for the vehicle and providing sustained power, while the supercapacitor mainly provides high-power auxiliary power during vehicle start-up and acceleration. Furthermore, supercapacitors can collect and store energy during vehicle braking, idling, deceleration, downhill driving, and other braking processes. They safely convert excess irregular power generated during vehicle operation into charging energy for the battery, protecting the battery's safe and stable operation. This energy recovery and reuse method effectively reduces the vehicle's energy consumption and emissions.

[0003] However, supercapacitors also have significant structural defects, such as low energy density, poor mechanical properties, and susceptibility to electrolyte leakage. In recent years, with the rapid development of electric vehicles and energy storage systems, the demand for high-performance electrolytes has been increasing. The electrolyte is one of the core components of a supercapacitor, and its performance directly affects the supercapacitor's energy density, power density, operating voltage, temperature adaptability, cycle life, and safety. Compared to liquid electrolytes, solid-state electrolytes offer higher safety, higher energy density, a wider operating temperature range, and longer lifespan. These advantages make solid-state electrolytes a promising candidate for application in battery technology. In recent years, various polymer-based hydrogels have been extensively studied, such as polyvinyl alcohol (PVA), polyacrylamide (PAAm), polyacrylic acid (PAA), and polyethylene glycol (PEG). For example, CN 116959893 A describes an ink / chitosan / polyacrylic acid composite hydrogel electrolyte and its preparation method and application. This composite hydrogel electrolyte is composed of ink, chitosan, polyacrylic acid, and ferric chloride hexahydrate. The specific preparation steps include: mixing traditional Chinese ink with an acetic acid solution of chitosan, then sequentially adding acrylic acid, ferric chloride hexahydrate, and an initiator; heating to initiate acrylic acid polymerization to obtain a pregel; and immersing the pregel in an aqueous sodium chloride solution to obtain a composite hydrogel electrolyte. This invention has a simple preparation method, and the prepared composite hydrogel electrolyte exhibits high conductivity and excellent self-healing properties. Its conductivity and self-healing properties can be controlled by adjusting the ink content, chitosan and iron ion concentrations, and immersion time. However, polymer-based hydrogels exhibit lower electrochemical performance under deformation and lower mechanical properties in the presence of high-concentration salt solutions. To obtain higher ionic conductivity, a mature method is used: incorporating high-conductivity materials, such as carbon nanotubes, into the hydrogel matrix. Graphene oxide or MXene For example, CN 118553537 A discloses a graphene-based composite electrode material and its supercapacitor, solving the problems of low specific capacity and complex electrode preparation process of graphene electrode materials, belonging to the field of electrochemical energy storage technology. This invention combines transition metal ions with catechol, uses laser direct writing technology to prepare interdigitated graphene electrodes, and employs electrochemical deposition technology to deposit the catechol / transition metal composite on the graphene electrodes, thus preparing a graphene composite electrode material with high specific capacity and high conductivity. This invention can significantly improve the energy storage characteristics of graphene electrodes, improve the wettability between graphene and electrolytes, and the composite electrode material has excellent conductivity. Furthermore, the process is simple and has a short cycle time. However, inevitably, the additives will disrupt the compactness of the hydrogel matrix, leading to a significant reduction in its mechanical properties.

[0004] Ideally, hydrogel electrolytes should maintain their structural integrity, rapidly recovering from their deformed state even under bending, twisting, and compression. Constructing a double-network structure for hydrogel electrolytes is beneficial for energy dissipation and has proven to be an effective method. Sodium alginate (SA) is a natural polymer rich in functional groups (hydroxyl and carboxyl groups). Utilizing the abundant functional groups of SA molecules and the long-chain structure of the polymer, hydrogel electrolytes with a double-network structure can be constructed through interactions between molecular chains. When the hydrogel electrolyte deforms under stress loads, its unique double-network structure accelerates energy dissipation through the breaking of physical bonds. Simultaneously, the formation of the three-dimensional porous network acts as a channel for ion transport, giving the hydrogel electrolyte higher conductivity. Although various double-network hydrogels have been designed and reported in previous work, many hydrogels can only be prepared under conditions requiring initiators, crosslinking agents, or additional conditions (heating, UV irradiation, ice bath). Therefore, developing a simple, rapid, and low-consumption method for preparing double-network hydrogel electrolytes remains a challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a biomass-based solid electrolyte, its preparation method and application. The electrolyte is prepared by forming an interpenetrating double-network hydrogel with sodium alginate and polyvinyl alcohol through hydrogen bonding, introducing graphene into the hydrogel, and using microfluidic technology and ion crosslinking at low salt concentration to significantly improve the electrochemical and mechanical properties of the electrolyte.

[0006] The specific details of the plan are as follows:

[0007] A biomass-based solid electrolyte, by mass percentage, comprises 9.0%-21.4% polyvinyl alcohol, 2.9%-12.7% sodium alginate, 1.5%-6.5% sodium chloride, 1.4%-8.9% borax, 0.3%-1.5% graphene, with the remainder being deionized water.

[0008] Furthermore, by mass percentage, the chemical composition includes 13.4%-17.5% polyvinyl alcohol, 3.5%-8.6% sodium alginate, 3.2%-6.3% sodium chloride, 2.4%-7.5% borax, 0.36%-8.9% graphene, and the remainder is deionized water.

[0009] Furthermore, the maximum tensile stress of the biomass-based solid electrolyte is 176-912 kPa, and the maximum elongation is 419%-1060%.

[0010] A method for preparing a biomass-based solid electrolyte, comprising the following steps:

[0011] S1. Preparation of graphene: A certain amount of graphite powder and an equal amount of... Add the contents to a container, then add 98% concentrated sulfuric acid while stirring continuously. Then slowly add the following to the container: ,in: and The mass ratio is 1:6. After adding the ingredients, the temperature is raised to 35 ℃ and stirred for 10 h.

[0012] S2. After heating is complete, slowly add deionized water dropwise to the container, then raise the temperature to 80 ℃ and maintain it for 30 min, then add... Finally, the graphene suspension was obtained by multiple centrifugations with 5% HCl and deionized water. The suspension was then prepared into 2... The solution is ready for use;

[0013] S3. Add polyvinyl alcohol solution to a container, and while stirring, add a certain mass of sodium alginate and graphene solution to the polyvinyl alcohol solution respectively. Then, add conductive ion salt solutions of different concentrations to the above solution and continue stirring. After ultrasonic treatment in an ultrasonic cleaner, remove the air bubbles in the solution.

[0014] S4. Using microfluidic technology, the borax solution is stably and slowly added to the solution in step S3, and after standing for a period of time, the black biomass-based solid electrolyte is formed.

[0015] Further, in step S3, polyvinyl alcohol solution is added to a beaker, and sodium alginate and graphene solution are added to the polyvinyl alcohol solution separately while stirring at 400 rpm for 1 hour until sodium alginate is completely dissolved.

[0016] Furthermore, in step S3, the conductive ion salt solution is a NaCl solution. After adding the NaCl solution, the mixture is stirred at 500 rpm for 1 hour.

[0017] Furthermore, in step S3, an ultrasonic cleaner with a power of 500W is used to ultrasonically treat the sample for 30 minutes.

[0018] Furthermore, in step S4, the borax solution is at 4... The solution is added slowly and steadily to the solution obtained in step S3.

[0019] A supercapacitor is assembled using activated carbon as the electrolytic material and the aforementioned biomass-based solid electrolyte.

[0020] Furthermore, at a current density of 1 At that time, the specific capacitance of the supercapacitor was 105.4-161.4. The interface impedance is 4.3-16.77 Ω.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] 1. Sodium alginate molecular chains and polyvinyl alcohol molecular chains can form an interpenetrating double network hydrogel through hydrogen bonds. The abundant porous structure in the hydrogel accelerates the migration rate of ions during charging and discharging and the energy consumption during deformation, which significantly improves the mechanical and electrochemical properties of the hydrogel solid electrolyte.

[0023] 2. Graphene's high conductivity, high light transmittance, and flexibility make it important for applications in transparent electrodes. Introducing graphene into hydrogels not only increases the hydrogel's conductivity and enhances the interaction between polyvinyl alcohol and sodium alginate molecular chains, but also further improves the mechanical and electrochemical properties of the hydrogel solid electrolyte.

[0024] 3. Sodium alginate is low in cost, abundant in source, and has advantages such as excellent water retention, biodegradability, biocompatibility and stability; polyvinyl alcohol is a colorless, non-toxic, non-corrosive and biodegradable water-soluble high molecular organic polymer, which is widely used in the field of flexible materials. Attached Figure Description

[0025] Figure 1 Example 3: Biomass-based solid electrolyte SEM image. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0027] The terminology used in this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in this invention and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0028] It should be noted that the terms "front", "rear", "inner", "outer", "left", "right", etc., used in this invention refer to the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0029] This invention provides a biomass-based solid electrolyte, which, by mass percentage, comprises 9.0%-21.4% polyvinyl alcohol, 2.9%-12.7% sodium alginate, 1.5%-6.5% sodium chloride, 1.4%-8.9% borax, 0.3%-1.5% graphene, and the remainder being deionized water.

[0030] Based on the chemical and mechanical properties of the supercapacitor, the chemical composition is further preferably: 13.4%-17.5% polyvinyl alcohol, 3.5%-8.6% sodium alginate, 3.2%-6.3% sodium chloride, 2.4%-7.5% borax, 0.36%-8.9% graphene, and the remainder is deionized water.

[0031] The maximum tensile stress of the biomass-based solid electrolyte of the present invention is 176-912 kPa, and the maximum elongation is 419%-1060%.

[0032] This invention also provides a method for preparing a biomass-based solid electrolyte, which employs microfluidic technology and an ion crosslinking method at low salt concentrations. The specific steps include:

[0033] S1. Preparation of graphene: A certain amount of graphite powder and an equal amount of... Add the contents to a container, then add 98% concentrated sulfuric acid while stirring continuously. Then slowly add the following to the container: ,in: and The mass ratio is 1:6. After adding the ingredients, the temperature is raised to 35 ℃ and stirred for 10 h.

[0034] S2. After heating is complete, slowly add deionized water dropwise to the container, then raise the temperature to 80 ℃ and maintain it for 30 min, then add... Finally, the graphene suspension was obtained by multiple centrifugations with 5% HCl and deionized water. The suspension was then prepared into 2... The solution is ready for use;

[0035] S3. Add polyvinyl alcohol solution to a container, and while stirring, add a certain mass of sodium alginate and graphene solution to the polyvinyl alcohol solution respectively. Then, add conductive ion salt solutions of different concentrations to the above solution and continue stirring. After ultrasonic treatment in an ultrasonic cleaner, remove the air bubbles in the solution.

[0036] S4. Using microfluidic technology, the borax solution is stably and slowly added to the solution in step S3, and after standing for a period of time, the black biomass-based solid electrolyte is formed.

[0037] In step S3, polyvinyl alcohol solution is added to a beaker, and sodium alginate and graphene solution are added to the polyvinyl alcohol solution separately while stirring at 400 rpm for 1 hour until sodium alginate is completely dissolved.

[0038] In step S3, the conductive ion salt solution is a NaCl solution. After adding the NaCl solution, the mixture is stirred at 500 rpm for 1 hour.

[0039] In step S3, an ultrasonic cleaner with a power of 500W is used to ultrasonically treat the sample for 30 minutes.

[0040] In step S4, the borax solution is at 4 The solution is added slowly and steadily to the solution obtained in step S3.

[0041] This invention also provides a supercapacitor assembled using activated carbon as the electrolytic material and the aforementioned biomass-based solid electrolyte. The supercapacitor was assembled using activated carbon as the electrolytic material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results show that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 105.4-161.4. The interface impedance is 4.3-16.77Ω.

[0042] The following examples are in conjunction with Examples 1-7, Comparative Examples 1-2, and Figure 1 The present invention will be described in detail below:

[0043] Example 1:

[0044] Preparation of graphene: 1 g of graphite powder and 1 g of graphene powder were mixed. Add the contents to a beaker, then add 46 mL of 98% concentrated sulfuric acid and stir continuously. Then slowly add 6 g of [amount missing] to the beaker. After adding the solution, heat to 35 °C and stir for 10 h. After heating, slowly add 80 mL of deionized water dropwise to the beaker, then heat to 80 °C and maintain for 30 min. Next, add another 120 mL of deionized water, and then add 6 mL of the above solution. Finally, the graphene suspension was obtained by multiple centrifugations with 5% HCl and deionized water. The suspension was then prepared into 2... The solution is ready for use.

[0045] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 3.5% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.8% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 105.4. The interfacial impedance is 10.36 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 409 kPa, and the maximum elongation is 419%.

[0046] Example 2:

[0047] The preparation of graphene was the same as in Example 1.

[0048] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 5.2% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.8% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 112.7. The interfacial impedance is 6.85 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 669 kPa, and the maximum elongation is 581%.

[0049] Example 3:

[0050] The preparation of graphene was the same as in Example 1.

[0051] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 6.9% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.8% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 158.5. The interfacial impedance is 4.34 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 912 kPa, and the maximum elongation is 842%.

[0052] The SEM image of the solid electrolyte prepared in this embodiment is as follows: Figure 1 As shown, due to the addition of sodium alginate, the solid electrolyte changes from a 2D planar structure to a 3D interpenetrating network structure. The rich and uniform pore structure not only accelerates the energy dissipation of the solid electrolyte during deformation, but also serves as a channel for ion transport, accelerating the ion transport rate during charging and discharging, thereby improving the mechanical properties and energy storage performance of the solid electrolyte.

[0053] Example 4:

[0054] The preparation of graphene was the same as in Example 1.

[0055] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 8.6% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.8% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 100.2. The interfacial impedance is 16.77 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 176 kPa, and the maximum elongation is 233%.

[0056] Example 5:

[0057] The preparation of graphene was the same as in Example 1.

[0058] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 6.9% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 3.2% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrolytic material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 110.5. The interfacial impedance is 10.42 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 410 kPa, and the maximum elongation is 1060%.

[0059] Example 6:

[0060] The preparation of graphene was the same as in Example 1.

[0061] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 6.9% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.1% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 130.4. The interfacial impedance is 7.54 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 680 kPa, and the maximum elongation is 932%.

[0062] Example 7:

[0063] The preparation of graphene was the same as in Example 1.

[0064] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 6.9% sodium alginate and 0.7% graphene solution were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 6.3% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added at a 4... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm). The electrochemical properties of the supercapacitor were tested using an electrochemical workstation in a two-electrode system. Experimental results showed that at a current density of 1... At that time, the specific capacitance of the supercapacitor was 161.4. The interfacial impedance is 8.06 Ω. Mechanical property test results show that the maximum tensile stress of the solid electrolyte is 937 kPa, and the maximum elongation is 630%.

[0065] The solid electrolyte samples and supercapacitor samples prepared in Examples 1-7 were tested, and the results are shown in Table 1 below:

[0066]

[0067] The solid electrolyte samples and supercapacitor samples prepared in Examples 1-4 were tested. The results showed that the solid electrolyte with 6.9% sodium alginate in Example 3 exhibited the best electrochemical performance and good mechanical properties. When the mass percentage of sodium alginate exceeded 8.6%, a 3D mesh structure could not be formed, resulting in a significant decrease in specific capacitance, tensile stress, and elongation, an increase in impedance, and a deterioration in technical performance.

[0068] A comparison of the test results of the solid electrolyte samples and supercapacitor samples in Examples 5-7 shows that the specific capacitance of the solid electrolyte increases with the increase of NaCl content. This is because the increased Na+ content allows the supercapacitor to transport more conductive ions per unit time, improving the ion transport efficiency of the solid electrolyte. On the other hand, the addition of NaCl also causes a salting-out effect in the hydrogel, making the solid electrolyte more robust. Therefore, the maximum tensile stress of the solid electrolyte increases with the increase of NaCl content, while the maximum elongation gradually decreases. When the mass percentage of NaCl added is 4.8%, the solid electrolyte exhibits relatively ideal mechanical and electrochemical properties.

[0069] Comparative Example 1:

[0070] The preparation of graphene was the same as in Example 1.

[0071] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 5.3% sodium alginate and 0.3% MXene were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.2% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm).

[0072] Comparative Example 2:

[0073] The preparation of graphene was the same as in Example 1.

[0074] A 15% (w / w) polyvinyl alcohol solution was added to a container. While mechanically stirring, 5.3% sodium alginate and 0.6% carbon nanotubes were added separately. The mixture was stirred for 1 hour at 400 rpm until the sodium alginate was completely dissolved. Then, 4.5% sodium chloride was added to the solution, and the mixture was stirred at a certain temperature for 1 hour at 500 rpm. The mixture was then ultrasonically treated in a 500 W ultrasonic cleaner for 30 minutes to thoroughly remove air bubbles. Finally, a 4% (w / w) borax solution was added... The electrolyte is added slowly and steadily to a completely degassed solution, and allowed to stand for 10 minutes to obtain the prepared solid electrolyte, denoted as . A supercapacitor was assembled using activated carbon as the electrode material and a solid electrolyte (10 mm × 10 mm × 3 mm).

[0075] The solid electrolyte samples and supercapacitor samples prepared in Comparative Examples 1 and 2 were tested, and the test results were compared with the test parameters of Example 3. The results are shown in Table 2.

[0076]

[0077] To fully evaluate the beneficial effects of the present invention, Comparative Examples 1 and 2 were designed to be compared with Example 3. The solid electrolyte samples and supercapacitor samples prepared by Comparative Examples 1 and 2 were tested, and compared with Example 3, it was found that adding other carbon materials did not have any advantage in performance improvement compared with the technical solution of the present invention.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biomass-based solid electrolyte, characterized in that, By mass percentage, the chemical composition includes 9.0%-21.4% polyvinyl alcohol, 2.9%-12.7% sodium alginate, 1.5%-6.5% sodium chloride, 1.4%-8.9% borax, 0.3%-1.5% graphene, and the remainder is deionized water.

2. The biomass-based solid electrolyte according to claim 1, characterized in that, By mass percentage, the chemical composition includes 13.4%-17.5% polyvinyl alcohol, 3.5%-8.6% sodium alginate, 3.2%-6.3% sodium chloride, 2.4%-7.5% borax, 0.36%-8.9% graphene, and the remainder is deionized water.

3. The biomass-based solid electrolyte according to claim 1, characterized in that, The maximum tensile stress of the biomass-based solid electrolyte is 176-912 kPa, and the maximum elongation is 419%-1060%.

4. A method for preparing a biomass-based solid electrolyte, characterized in that, The specific steps for preparing the biomass-based solid electrolyte as described in any one of claims 1-3 include: S1. Preparation of graphene: A certain amount of graphite powder and an equal amount of... Add the contents to a container, then add 98% concentrated sulfuric acid while stirring continuously. Then slowly add the following to the container: ,in: and The mass ratio is 1:

6. After adding the ingredients, the temperature is raised to 35 ℃ and stirred for 10 h. S2. After heating is complete, slowly add deionized water dropwise to the container, then raise the temperature to 80 ℃ and maintain it for 30 min, then add... Finally, the graphene suspension was obtained by multiple centrifugations with 5% HCl and deionized water. The suspension was then prepared into 2... The solution is ready for use; S3. Add polyvinyl alcohol solution to a container, and while stirring, add a certain mass of sodium alginate and graphene solution to the polyvinyl alcohol solution respectively. Then, add conductive ion salt solutions of different concentrations to the above solution and continue stirring. After ultrasonic treatment in an ultrasonic cleaner, remove the air bubbles in the solution. S4. Using microfluidic technology, the borax solution is stably and slowly added to the solution in step S3, and after standing for a period of time, the black biomass-based solid electrolyte is formed.

5. The method for preparing biomass-based solid electrolyte according to claim 4, characterized in that, In step S3, polyvinyl alcohol solution is added to a beaker. Sodium alginate and graphene solution are added to the polyvinyl alcohol solution separately while stirring at 400 rpm for 1 hour until sodium alginate is completely dissolved.

6. The method for preparing biomass-based solid electrolyte according to claim 4, characterized in that, In step S3, the conductive ion salt solution is a NaCl solution. After adding the NaCl solution, the mixture is stirred at 500 rpm for 1 hour.

7. The method for preparing biomass-based solid electrolyte according to claim 4, characterized in that, In step S3, an ultrasonic cleaner with a power of 500W is used to ultrasonically treat the sample for 30 minutes.

8. The method for preparing biomass-based solid electrolyte according to claim 4, characterized in that, In step S4, the borax solution is at 4 The solution is added slowly and steadily to the solution obtained in step S3.

9. A supercapacitor, characterized in that, It is assembled using activated carbon as the electrolytic material and the biomass-based solid electrolyte as described in any one of claims 1-3.

10. The supercapacitor according to claim 9, characterized in that, At a current density of 1 At that time, the specific capacitance of the supercapacitor was 105.4-161.

4. The interface impedance is 4.3-16.77 Ω.

Images