High-swelling-rate solid gel electrolyte and preparation method and application thereof
By introducing sodium polyacrylate and KOH into the polyvinyl alcohol gel electrolyte, a high swelling rate solid gel electrolyte with a double network structure is formed, which solves the problems of insufficient swelling performance and water retention performance of traditional gel electrolytes, and achieves better battery performance and longer cycle life.
Patent Information
- Application Number
- CN202510952110.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-10-17
AI Technical Summary
The existing polyvinyl alcohol gel electrolyte has insufficient swelling and water retention properties in flexible wearable aluminum-air batteries, resulting in reduced ionic conductivity and making it difficult to meet the needs of flexible wearable products.
Sodium polyacrylate and strong base KOH are introduced to form a high swelling rate solid gel electrolyte with a double network structure through freeze cross-linking, which improves the swelling performance and water retention performance of the electrolyte.
It significantly improves the absorption capacity and ionic conductivity of the electrolyte, enhances the discharge stability and cycle performance of the battery, and extends the cycle life of the aluminum-air battery.
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Figure CN120810094A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of metal-air batteries, and particularly relates to a high-swelling-rate solid-state gel electrolyte and a preparation method and application thereof. BACKGROUND
[0002] In recent years, flexible wearable electronic devices have shown great application potential in many fields such as medical treatment, sports and health monitoring. As a key power component of flexible wearable electronic devices, the role and advantages of aluminum-air batteries cannot be ignored. Compared with traditional batteries, aluminum-air batteries have higher energy density and produce less environmental pollution in the production and use process. At the same time, aluminum-air batteries have higher safety and are not prone to leakage, explosion and other dangerous situations. With the advantages of high energy density, lightness, flexibility, environmental protection, safety and long service life, aluminum-air batteries provide a broad prospect for the rapid development of such devices.
[0003] In a flexible rechargeable aluminum-air battery, a polymer gel electrolyte (GPE) is an extremely important component. The solidification of the gel electrolyte improves safety and portability, and also has good mechanical properties and stability. Although polyvinyl alcohol (PVA) widely used at present has good biocompatibility and excellent mechanical strength, its liquid absorption rate is low. The poor swelling performance caused by insufficient electrolyte retention and supply capacity not only leads to a significant reduction in ionic conductivity, but also lacks flexibility, making it difficult to fully conform to flexible wearable products. SUMMARY
[0004] In order to overcome the shortcomings of the prior art, the purpose of the present application is to provide a high-swelling-rate solid-state gel electrolyte and a preparation method and application thereof. Sodium polyacrylate (PAAS) is introduced, which contains a large number of carboxylate groups and has the characteristics of high water absorption rate and fast water absorption speed, so as to improve the capacity of the solid-state electrolyte to accommodate electrolyte.
[0005] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: The present application provides a preparation method of a high-swelling-rate solid-state gel electrolyte, comprising the following steps: Polyvinyl alcohol is added to deionized water to obtain a polyvinyl alcohol sol; KOH is added to deionized water to prepare a basic solution, and sodium polyacrylate is added to the basic solution in small amounts and multiple times to obtain a basic solution containing high molecular weight sodium polyacrylate; The basic solution containing high molecular weight sodium polyacrylate is mixed with the polyvinyl alcohol sol and stirred uniformly, and the mixed solution is prepared from a viscous state to a light yellow clear sol state. The sol solution is treated by freeze-thaw method, and the gel electrolyte is repeatedly formed for multiple times, and then the gel electrolyte is soaked in the electrolyte solution to obtain the solid gel electrolyte.
[0006] In an embodiment, the polyvinyl alcohol has a molecular weight greater than 1000 and less than 100000, and the sodium polyacrylate has a molecular weight greater than 1000 and less than 100000.
[0007] In an embodiment, the mass ratio of the polyvinyl alcohol, the sodium polyacrylate and the KOH is 4.00:(1.00-1.20):(0.80-1.10).
[0008] In an embodiment, the polyvinyl alcohol is added to the deionized water to obtain the polyvinyl alcohol sol, and the process is as follows: the polyvinyl alcohol is put into the deionized water for stirring for 15-20 min and soaking, and then the stirring is continued at 80-90℃ until the polyvinyl alcohol is completely dissolved to obtain the polyvinyl alcohol sol; the dosage ratio of the polyvinyl alcohol and the deionized water is (3.74-4.0) g:15 ml.
[0009] In an embodiment, the pH value of the alkaline solution is 8-9, and the dosage ratio of the KOH and the deionized water in the alkaline solution is (0.97-1.16) g:15 ml.
[0010] In an embodiment, the stirring time of the alkaline solution containing the sodium polyacrylate with high molecular weight and the polyvinyl alcohol sol after mixing is 30-40 min, and the stirring temperature is 80-90℃.
[0011] In an embodiment, the freezing temperature of the freeze-thaw treatment is minus 18-28℃, the freezing time is 25-30 min, and the standing time is 25-30 min; the number of repeated times is 3-5 times.
[0012] In an embodiment, the electrolyte solution is a 6-8 mol / L KOH solution or a NaOH solution, and the soaking time is 24-30 h.
[0013] The application further provides a high-swelling-rate solid gel electrolyte prepared by the preparation method of the high-swelling-rate solid gel electrolyte, and the high-swelling-rate solid gel electrolyte has a double network structure formed by a network structure composed of polyvinyl alcohol and a network structure composed of sodium polyacrylate.
[0014] The application further provides an application of the high-swelling-rate solid gel electrolyte prepared by the preparation method of the high-swelling-rate solid gel electrolyte in an aluminum-air battery.
[0015] Compared with the prior art, the application has the following beneficial effects: The present application provides a preparation method of a high-swelling-rate solid-state gel electrolyte. In the traditional polyvinyl alcohol gel electrolyte, an ultrahigh molecular weight sodium polyacrylate is introduced to improve the water retention performance of the solid-state electrolyte. A certain amount of strong alkali is added to the sodium polyacrylate aqueous solution to improve the dispersibility of the sodium polyacrylate in the polyvinyl alcohol solution. The present application uses polyvinyl alcohol (PVA), sodium polyacrylate (PAAS) and KOH as raw materials, which are added to water in stages to obtain a mixed solution, and then stirred to crosslink and polymerize to form a stable transparent colloidal solution, and then a solid-state gel electrolyte is prepared.
[0016] Further, the preparation process is simple and does not depend on complex equipment or conditions, so it can be implemented in various production environments. Only a simple container is needed, and the gel electrolyte can be prepared by simple operation. This method is not only efficient but also flexible, making the preparation of the gel electrolyte more convenient and economical.
[0017] The present application provides a high-swelling-rate solid-state gel electrolyte prepared by the above preparation method. Compared with the traditional polyvinyl alcohol gel electrolyte, the solid-state gel electrolyte has better swelling and water retention performance, significantly improves the electrolyte absorption capacity, and improves the discharge stability of the battery. The double network structure existing in the electrolyte can provide an ion transfer channel, and the electrolyte has good discharge performance and cycle performance, realizing a long cycle life of the aluminum-air battery. BRIEF DESCRIPTION OF DRAWINGS
[0018] Figure 1 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 1 of the present application is shown in the figure; Figure 2 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 2 of the present application is shown in the figure; Figure 3 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 3 of the present application is shown in the figure; Figure 4 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 4 of the present application is shown in the figure; Figure 5 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 5 of the present application is shown in the figure; Figure 6 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 6 of the present application is shown in the figure; Figure 7 The swelling curve of the high-swelling-rate solid-state gel electrolyte prepared for Example 7 of the present application is shown in the figure; Figure 8Swelling curve of high-swelling solid gel electrolyte prepared for embodiment 8 of the present application; Figure 9 Reaction mechanism schematic diagram of high-swelling solid gel electrolyte prepared for the present application when applied to aluminum-air battery for testing; Figure 10 Disassembled schematic diagram of testing device of high-swelling solid gel electrolyte prepared for the present application when applied to aluminum-air battery for testing; Figure 11 Overall schematic diagram of testing device of high-swelling solid gel electrolyte prepared for the present application when applied to aluminum-air battery for testing; Figure 12 Network structure diagram of comparative item polyvinyl alcohol conductive gel observed under scanning electron microscope; Figure 13 Double network structure diagram of the present application observed under scanning electron microscope. DETAILED DESCRIPTION
[0019] To enable persons skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.
[0020] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting the scope of the present application, i.e., the present application can be practiced without regard to any particular theory or mechanism.
[0021] Herein, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents and concentrations, are for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be considered to have encompassed and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).
[0022] Herein, unless otherwise specified, “comprise”, “include”, “contain”, “have” or similar words encompass the meaning of “consist of” and “consist essentially of”, for example, “A comprises a” encompasses the meaning of “A comprises a and other” and “A comprises only a”.
[0023] Herein, for the sake of brevity, all possible combinations of the technical features in each embodiment or example are not described. Therefore, as long as the combinations of the technical features do not contradict each other, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope disclosed in the specification.
[0024] The invention provides a high swelling rate solid gel electrolyte and a preparation method and application thereof.
[0025] On one hand, the present invention provides a method for preparing a solid gel electrolyte with a high swelling ratio, and the specific preparation method is as follows: S1. Preparation of polyvinyl alcohol sol: First, a certain mass of polyvinyl alcohol particles was placed in a three-necked flask with 15 ml of deionized water, stirred and soaked, and then the heating device was turned on and continued stirring at a certain temperature for a certain time until the polyvinyl alcohol particles were completely dissolved to obtain a polyvinyl alcohol sol; S2. Preparation of an alkaline solution containing a high molecular weight sodium polyacrylate: A certain mass of KOH was added to 15 ml of deionized water to form an alkaline solution. The magnetic stirring device was turned on and a certain mass of sodium polyacrylate was added in small amounts and stirred repeatedly until the sodium polyacrylate was evenly dispersed in the alkaline solution. S3. Preparation of sol solution: The alkaline solution of sodium polyacrylate prepared above was added to the polyvinyl alcohol sol, stirred continuously at a certain temperature, and the mixed solution was changed from a viscous state to a light yellow clear sol state; S4. Preparation of solid gel electrolyte: Pour the above sol solution into a mold, freeze it at a certain temperature for a certain time using the thawing method, take it out and let it stand, repeat this process several times to obtain a solid gel electrolyte; soak the obtained solid gel electrolyte in an electrolyte solution for a certain period of time.
[0026] In S1 and S2, the molecular weight of polyvinyl alcohol in the polyvinyl alcohol sol is greater than 1000 and less than 100000, the molecular weight of sodium polyacrylate is greater than 1000 and less than 100000, and the mass ratio of polyvinyl alcohol, sodium polyacrylate and KOH is 4.00:(1.00-1.20):(0.80-1.10).
[0027] In S1, the stirring time is 15-20 min, the heating temperature is 80-90° C. The amount ratio of polyvinyl alcohol particles to deionized water ranges from (3.74-4.0) g to 15 ml.
[0028] In S2, the stirring time is 5-10 min. The dosage ratio of KOH to deionized water ranges from (0.97-1.16) g:15 ml.
[0029] In S2, the pH value of the alkaline solution is 8-9.
[0030] In S3, the stirring time is 30-40 min, and the stirring temperature is 80-90°C.
[0031] In S4, the freezing temperature is -18-28°C, the freezing time is 25-30 minutes, and the standing time is 25-30 minutes. The number of times in S4 is repeated is 3-5 times.
[0032] In S4, the electrolyte solution is a 6-8 mol / L KOH solution or a NaOH solution, and the soaking time is 24-30 h.
[0033] Another aspect of the present application provides a high-swelling-rate solid gel electrolyte prepared by the above preparation method, which has a double-network structure formed by a network structure composed of polyvinyl alcohol and a network structure composed of sodium polyacrylate.
[0034] The present application also provides an application of the above high-swelling-rate solid gel electrolyte as an aluminum-air battery solid gel electrolyte.
[0035] The present application uses polyvinyl alcohol (PVA), sodium polyacrylate (PAAS) and KOH as raw materials, which are added to water in stages to obtain a mixed solution, and then stirred to crosslink, polymerize in the solution to form a stable transparent colloidal solution, and then a solid gel electrolyte is prepared. The gel electrolyte prepared by the present application has strong swelling and water retention properties, significantly improves the electrolyte absorption capacity and ionic conductivity, and improves the discharge stability of the battery; the double-network structure of the electrolyte provides an ion transfer channel, has good discharge performance and cycle performance, and realizes a long cycle life of the aluminum-air battery.
[0036] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. In addition, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.
[0037] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples not specified in the specific conditions, generally according to the conventional conditions, or according to the manufacturer's recommended conditions. Various raw materials are used in the following examples, unless otherwise specified, conventional commercially available products are used, which are conventional specifications in the art. In the specification of the present application and the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.
[0038] Example 1 (1) Preparation of polyvinyl alcohol sol: first, 4.0 g of polyvinyl alcohol particles were placed in a three-necked flask with 15 ml of deionized water, stirred and soaked, then the heating device was turned on, and the stirring was continued at 80℃ for 15 min, until the polyvinyl alcohol particles were completely dissolved to obtain a sol; (2) Preparation of the sodium polyacrylate alkaline solution: 1.0 g of KOH was added into 15 ml of deionized water to form an alkaline solution, and a magnetic stirring device was turned on. 0.8 g of sodium polyacrylate was added into the alkaline solution in small amounts and repeatedly stirred until the sodium polyacrylate was uniformly dispersed in the alkaline solution; (3) The prepared sodium polyacrylate alkaline solution was added into the polyvinyl alcohol sol, and stirred at 80°C for 30 min until the mixed solution changed from a viscous state to a light yellow clear sol state. The sol solution was poured into a mold, and a freeze-thaw method was used to freeze at -18°C for 25 min, and then the mold was taken out and placed for 25 min. The above process was repeated three times to obtain a solid gel electrolyte. (4) The obtained solid gel electrolyte was soaked in a 6 mol / L KOH solution electrolyte solution for 24 h.
[0039] Figure 1 The swelling curve of the sample prepared in Example 1 was measured. It can be obtained that the swelling rate of the gel electrolyte is 975.5%. Figure 1
[0040] Example 2 (1) Preparation of the polyvinyl alcohol sol: 3.93 g of polyvinyl alcohol particles were placed into a three-necked flask containing 15 ml of deionized water, and stirred and soaked. Then a heating device was turned on, and the stirring was continued at 90°C for 15 min until the polyvinyl alcohol particles were completely dissolved to obtain a sol. (2) Preparation of the sodium polyacrylate alkaline solution: 1.08 g of KOH was added into 15 ml of deionized water to form an alkaline solution, and a magnetic stirring device was turned on. 0.79 g of sodium polyacrylate was added into the alkaline solution in small amounts and repeatedly stirred until the sodium polyacrylate was uniformly dispersed in the alkaline solution. (3) The prepared sodium polyacrylate alkaline solution was added into the polyvinyl alcohol sol, and stirred at 90°C for 30 min until the mixed solution changed from a viscous state to a light yellow clear sol state. The sol solution was poured into a mold, and a freeze-thaw method was used to freeze at -18°C for 30 min, and then the mold was taken out and placed for 30 min. The above process was repeated three times to obtain a solid gel electrolyte. (4) The obtained solid gel electrolyte was soaked in a 6 mol / L KOH solution electrolyte solution for 24 h.
[0041] Figure 2 The swelling curve of the sample prepared in Example 2 was measured. It can be obtained that the swelling rate of the gel electrolyte is 981.5%. Figure 2
[0042] Example 3 (1) Preparation of polyvinyl alcohol sol: First, 3.87 g of polyvinyl alcohol particles were placed in a three-necked flask with 15 ml of deionized water and stirred and soaked. Then, the heating device was turned on and the mixture was stirred at 80 °C for 20 min until the polyvinyl alcohol particles were completely dissolved to obtain a sol. (2) Preparation of sodium polyacrylate alkaline solution: Add 1.16 g of KOH to 15 ml of deionized water to form an alkaline solution. Turn on the magnetic stirring device and add 0.77 g of sodium polyacrylate in small amounts and stir until the sodium polyacrylate is evenly dispersed in the alkaline solution. (3) Add the sodium polyacrylate alkaline solution prepared above to the polyvinyl alcohol sol and stir at 80°C for 40 minutes until the mixed solution changes from a viscous state to a light yellow clear sol state; pour the above sol solution into a mold and freeze it at -18°C for 25 minutes using the thawing method and let it stand for 25 minutes. Repeat this three times to obtain a solid gel electrolyte; (4) Soak the obtained solid gel electrolyte in 8 mol / L KOH solution electrolyte solution for 28 h.
[0043] Figure 3 This is the swelling curve of the sample prepared in Example 3. Figure 3 It can be seen that the swelling ratio of the gel electrolyte is 965.5%.
[0044] Example 4 (1) Preparation of polyvinyl alcohol sol: First, 3.87 g of polyvinyl alcohol particles were placed in a three-necked flask with 15 ml of deionized water and stirred and soaked. Then, the heating device was turned on and the mixture was stirred at 80 °C for 15 min until the polyvinyl alcohol particles were completely dissolved to obtain a sol. (2) Preparation of sodium polyacrylate alkaline solution: Add 1.06 g of KOH to 15 ml of deionized water to form an alkaline solution. Turn on the magnetic stirring device and add 0.87 g of sodium polyacrylate in small amounts and stir until the sodium polyacrylate is evenly dispersed in the alkaline solution. (3) Add the sodium polyacrylate alkaline solution prepared above to the polyvinyl alcohol sol and stir at 80°C for 40 minutes until the mixed solution changes from a viscous state to a light yellow clear sol state; pour the above sol solution into a mold and freeze it at -24°C for 25 minutes using the thawing method and let it stand for 25 minutes. Repeat this three times to obtain a solid gel electrolyte; (5) Soak the obtained solid gel electrolyte in 8 mol / L KOH solution electrolyte solution for 28 h.
[0045] Figure 4 This is the swelling curve of the sample prepared in Example 4. Figure 4The swelling rate of the gel electrolyte is 934%.
[0046] Example 5 (1) Preparation of polyvinyl alcohol sol: 3.80 g of polyvinyl alcohol particles were first placed in a three-necked flask with 15 ml of deionized water, stirred and soaked, then the heating device was turned on, and stirring was continued at 80°C for 15 min, until the polyvinyl alcohol particles were completely dissolved to obtain a sol; (2) Preparation of sodium polyacrylate alkaline solution: 1.04 g of KOH was added to 15 ml of deionized water to form an alkaline solution, the magnetic stirring device was turned on, and 0.96 g of sodium polyacrylate was added in small amounts and stirred repeatedly until the sodium polyacrylate was uniformly dispersed in the alkaline solution; (3) The above prepared sodium polyacrylate alkaline solution was added to the polyvinyl alcohol sol, stirred at 90°C for 30 min, and the mixed solution was changed from a viscous state to a light yellow clear sol state; the above sol solution was poured into a mold, and a freeze-thaw method was used, frozen at -24°C for 30 min, taken out and placed for 30 min, repeated three times to obtain a solid gel electrolyte; (4) The obtained solid gel electrolyte was soaked in an 8 mol / L KOH solution electrolyte solution for 30 h.
[0047] Figure 5 The swelling curve of the sample prepared in Example 5 was measured. From the swelling curve, it can be seen that the swelling rate of the gel electrolyte is 948.2%. Figure 5
[0048] Example 6 (1) Preparation of polyvinyl alcohol sol: 3.74 g of polyvinyl alcohol particles were first placed in a three-necked flask with 15 ml of deionized water, stirred and soaked, then the heating device was turned on, and stirring was continued at 80°C for 20 min, until the polyvinyl alcohol particles were completely dissolved to obtain a sol; (2) Preparation of sodium polyacrylate alkaline solution: 1.03 g of KOH was added to 15 ml of deionized water to form an alkaline solution, the magnetic stirring device was turned on, and 1.03 g of sodium polyacrylate was added in small amounts and stirred repeatedly until the sodium polyacrylate was uniformly dispersed in the alkaline solution; (3) The above prepared sodium polyacrylate alkaline solution was added to the polyvinyl alcohol sol, stirred at 90°C for 30 min, and the mixed solution was changed from a viscous state to a light yellow clear sol state; the above sol solution was poured into a mold, and a freeze-thaw method was used, frozen at -24°C for 30 min, taken out and placed for 30 min, repeated three times to obtain a solid gel electrolyte; (4) The obtained solid gel electrolyte was soaked in an 8 mol / L KOH solution electrolyte solution for 30 h.
[0049] Figure 6 This is the swelling curve of the sample prepared in Example 6. Figure 6 It can be seen that the swelling ratio of the gel electrolyte is 935.7%.
[0050] Example 7 (1) Preparation of polyvinyl alcohol sol: First, 3.93 g of polyvinyl alcohol particles were placed in a three-necked flask with 15 ml of deionized water and stirred and soaked. Then, the heating device was turned on and the mixture was stirred at 80 °C for 15 min until the polyvinyl alcohol particles were completely dissolved to obtain a sol. (2) Preparation of sodium polyacrylate alkaline solution: Add 0.98 g of KOH to 15 ml of deionized water to form an alkaline solution. Turn on the magnetic stirring device and add 0.89 g of sodium polyacrylate in small amounts and stir until the sodium polyacrylate is evenly dispersed in the alkaline solution. (3) Add the sodium polyacrylate alkaline solution prepared above to the polyvinyl alcohol sol and stir at 80°C for 30 minutes until the mixed solution changes from a viscous state to a light yellow clear sol state; pour the above sol solution into a mold and freeze it at -24°C for 25 minutes using the thawing method and let it stand for 25 minutes. Repeat this three times to obtain a solid gel electrolyte; (4) Soak the obtained solid gel electrolyte in 6 mol / L NaOH solution electrolyte solution for 24 hours.
[0051] Figure 7 This is the swelling curve of the sample prepared in Example 7. Figure 7 It can be seen that the swelling ratio of the gel electrolyte is 958.6%.
[0052] Example 8 (1) Preparation of polyvinyl alcohol sol: First, 3.87 g of polyvinyl alcohol particles were placed in a three-necked flask with 15 ml of deionized water and stirred and soaked. Then, the heating device was turned on and the mixture was stirred at 90 °C for 20 min until the polyvinyl alcohol particles were completely dissolved to obtain a sol. (2) Preparation of sodium polyacrylate alkaline solution: Add 0.97 g of KOH to 15 ml of deionized water to form an alkaline solution. Turn on the magnetic stirring device and add 0.96 g of sodium polyacrylate in small amounts and stir until the sodium polyacrylate is evenly dispersed in the alkaline solution. (3) Add the sodium polyacrylate alkaline solution prepared above to the polyvinyl alcohol sol and stir at 90°C for 40 minutes until the mixed solution changes from a viscous state to a light yellow clear sol state; pour the above sol solution into a mold and freeze it at -28°C for 30 minutes using the thawing method and let it stand for 30 minutes. Repeat this three times to obtain a solid gel electrolyte; (4) The obtained solid gel electrolyte is soaked in 8 mol / L NaOH electrolyte solution for 24 h.
[0053] Figure 8 The swelling curve of the sample prepared in Example 8 is measured. It is found that the swelling rate of the gel electrolyte is 985.3%. Figure 8
[0054] Referring to Figure 9 , when the aluminum-air battery using the high-swelling-rate solid gel electrolyte prepared by the application is discharged, the metal aluminum anode undergoes oxidation reaction to generate Al(OH)3, and oxygen undergoes cathodic reduction reaction on the air electrode to generate OH - , in this process, the chemical energy stored in the metal aluminum is converted into a large amount of electrical energy and provided to the external circuit, and the specific reaction process equation is as follows: Anode: Al + 3OH - -3e - → Al(OH)3 Cathode: O2+ 2H2O + 4e - → 4OH - Overall battery reaction: 4Al + 3O2+ 6H2O → 4Al(OH)3 The assembly method of the aluminum-air battery using the high-swelling-rate solid gel electrolyte prepared by the application is as follows: combining the "aluminum electrode-separator-air electrode" three-layer structure in Figure 9 , the solid gel electrolyte is used to replace the traditional liquid electrolyte and integrated with the function of the separator. Aluminum electrode preparation: pure aluminum with a certain thickness is purchased and cut into circular or square pieces as the negative electrode. Air electrode preparation: Pt / C electrocatalyst or palladium-carbon catalyst is coated on the surface of a porous nickel mesh or carbon cloth, and dried as the positive electrode. Electrolyte layer integration: the pre-prepared solid gel electrolyte is placed between the aluminum electrode and the air electrode, replacing the traditional separator and liquid electrolyte. Sealing assembly: the three-layer structure (aluminum electrode / gel electrolyte / air electrode) is stacked, and the edge is sealed with a polytetrafluoroethylene frame to ensure that air can enter from the positive electrode side while preventing the gel from dehydrating.
[0055] Figure 10 and Figure 11 shows a clamp device specially designed for performance testing of solid gel electrolyte. The device tests the discharge performance of the negative aluminum sheet and the positive conductive nickel foam in the blue electricity test system under the condition of 2 mA constant current.
[0056] As Figure 10 As shown, the test device adopts a modular disassembly design, and the core components include three mold plates, matching screws and nuts, and an intermediate sandwich structure. Among them, the anode metal aluminum sheet and the positive electrode conductive nickel foam are fixed on the inner side of the mold plate, and mechanical fixation and electrical connection are realized through screws and nuts. This disassembly structure is convenient for assembly, debugging and replacement of key components.
[0057] Figure 11 The assembled form of the device is presented, which is composed of Figure 10 disassembled components fastened by screws and nuts. When assembled, the solid-state gel electrolyte to be tested is placed in the designated area of the intermediate mold plate, forming a "mold plate-electrolyte-mold plate" stacked structure, and the electrodes on both sides are in contact with the aluminum sheet and the nickel foam, finally forming a complete electrochemical test unit. This design not only ensures the stable clamping of the test sample, but also realizes the effective contact between the electrolyte and the electrode interface.
[0058] Referring to Figure 12 , the figure is a scanning electron microscope image of the comparative item polyvinyl alcohol conductive gel, which presents the pore structure characteristics of the gel surface. The distribution state of such pores has a key influence on the ion transmission performance of the gel - the migration behavior of ions in the gel system is highly dependent on the three-dimensional transmission channels constructed by the pores.
[0059] Referring to Figure 13 , the figure is a scanning electron microscope image of the solid-state gel electrolyte prepared by the present application. Compared with Figure 12 polyvinyl alcohol conductive gel, its surface structure is more complex, the hole size is unevenly distributed, and a dense layered structure appears on the surface. The double network structure (network structure composed of polyvinyl alcohol and network structure composed of sodium polyacrylate) provides more ion channels and improves the mechanical properties.
[0060] Compared with the pore structure of the polyvinyl alcohol conductive gel in Figure 12 , the surface of the solid-state gel electrolyte presents a more complex multi-level structure feature: the hole size is unevenly distributed, and a dense layered structure is visible on the surface. The above unique structural characteristics are due to the double network architecture, that is, the first heavy network structure constructed by polyvinyl alcohol molecular chains and the second heavy network structure formed by polyacrylic acid sodium molecular chains are interwoven. The synergistic effect of the double network structure not only constructs more abundant ion transmission channels, significantly improves the ion migration efficiency, and greatly improves the mechanical strength and structural stability of the gel.
[0061] In summary, the application provides a preparation method of a high-swelling-rate solid-state gel electrolyte for an aluminum-air battery and an application thereof. The preparation method is as follows: uniformly dispersing polyvinyl alcohol in deionized water and stirring at a certain temperature; uniformly dispersing a certain amount of KOH in deionized water and uniformly dispersing sodium polyacrylate in the alkaline solution and mixing uniformly; mixing the above alkaline mixed solution and the melted polyvinyl alcohol solution uniformly at a certain temperature; pouring the mixed solution into a mold and forming a solid-state gel electrolyte by a freeze-thaw method; and finally, soaking the prepared gel electrolyte in an electrolyte aqueous solution of a certain concentration to obtain a double-network solid-state gel electrolyte. The application introduces ultrahigh molecular weight sodium polyacrylate into a traditional polyvinyl alcohol gel electrolyte to improve the swelling performance and water retention performance of the solid-state electrolyte, and adds a certain amount of strong alkali to the sodium polyacrylate aqueous solution to improve the dispersibility of the sodium polyacrylate in the polyvinyl alcohol solution. Compared with the traditional polyvinyl alcohol gel electrolyte, the application can effectively inhibit water evaporation and has strong water retention performance; the double-network structure of the electrolyte provides an ion transfer channel and has good discharge performance and cycle performance, realizing a long cycle life of the aluminum-air battery.
[0062] The above merely describes the technical idea of the application and cannot limit the protection scope of the application. Any modification made according to the technical idea of the application on the basis of the technical solution falls within the protection scope of the claims of the application.
Claims
1. A method for preparing a high swelling ratio solid gel electrolyte, characterized in that: The following steps are involved: Adding polyvinyl alcohol into deionized water to obtain polyvinyl alcohol sol; KOH is added to deionized water to prepare an alkaline solution, and sodium polyacrylate is added to the alkaline solution in small amounts and multiple times to obtain an alkaline solution containing sodium polyacrylate with a high molecular weight; The sodium polyacrylate alkaline solution containing a high molecular weight is mixed with the polyvinyl alcohol sol and stirred evenly until the mixed solution changes from a viscous state to a light yellow clear sol state to prepare a sol solution; The sol solution is frozen and allowed to stand by a thawing method, and the process is repeated several times to form a gel electrolyte, which is then immersed in an electrolyte solution to obtain a solid gel electrolyte.
2. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The molecular weight of the polyvinyl alcohol is greater than 1,000 and less than 100,000, and the molecular weight of the sodium polyacrylate is greater than 1,000 and less than 100,000.
3. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The mass ratio of the polyvinyl alcohol, sodium polyacrylate and KOH is 4.00:(1.00-1.20):(0.80-1.10).
4. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The process of adding polyvinyl alcohol to deionized water to obtain polyvinyl alcohol sol is as follows: adding polyvinyl alcohol to deionized water and stirring for 15-20 minutes and soaking, and then continuing to stir at 80-90° C. until the polyvinyl alcohol is completely dissolved to obtain polyvinyl alcohol sol; The dosage ratio of polyvinyl alcohol and deionized water is (3.74-4.0) g:15 ml.
5. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The pH value of the alkaline solution is 8-9, and the dosage ratio of KOH to deionized water in the alkaline solution is (0.97-1.16) g:15 ml.
6. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The sodium polyacrylate alkaline solution containing a high molecular weight is mixed with the polyvinyl alcohol sol and stirred evenly for 30-40 minutes at a stirring temperature of 80-90°C.
7. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The freezing and standing treatment is performed at a freezing temperature of -18-28°C, a freezing time of 25-30 minutes, and a standing time of 25-30 minutes; and the process is repeated 3-5 times.
8. The method for preparing a high swelling ratio solid gel electrolyte according to claim 1, wherein: The electrolyte solution is a 6-8 mol / L KOH solution or a NaOH solution, and the soaking time is 24-30 hours.
9. A high swelling ratio solid gel electrolyte prepared by the method for preparing a high swelling ratio solid gel electrolyte according to any one of claims 1 to 8, characterized in that: The high swelling ratio solid gel electrolyte has a double network structure, which is formed by a network structure composed of polyvinyl alcohol and a network structure composed of sodium polyacrylate.
10. Use of a high swelling ratio solid gel electrolyte prepared by the method for preparing a high swelling ratio solid gel electrolyte according to any one of claims 1 to 8 in an aluminum-air battery.