Air electrode with integrated structure as well as preparation method and application of air electrode
By adopting an integrated structure air electrode in zinc-air batteries, combining carbon nanotubes and PVA gel electrolytes, and forming a transparent film-like catalyst on its surface, the problems of catalyst loss and poor interface compatibility are solved, and higher electrochemical performance and cyclic stability are achieved.
Patent Information
- Application Number
- CN202510393071.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-31
- Publication Date
- 2025-07-01
AI Technical Summary
The existing zinc-air battery air electrodes have problems such as cathode overflow, catalyst loss and poor interface compatibility, resulting in poor electrochemical performance and low cycling stability.
Using an integrated structure, the air electrode is used to add carbon nanotube-PVA precursor liquid droplets to the PVA gel electrolyte, and the refrigeration and thawing are repeated several times to form a stable air electrode carrier, and the surface is coated with a transparent film-like catalyst, and polytetrafluoroethylene is used to promote the formation of platinum carbon and ruthenium oxide.
It effectively prevents catalyst loss, improves the adhesion stability of the catalyst, reduces the interface impedance, enhances the cycle stability of the battery, and solves the cathode overflow problem, ensuring the smooth passage of gas in the electrode area.
Smart Images
Figure CN120237221A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of zinc-air batteries, and particularly relates to an air electrode with an integrated structure, a preparation method thereof, and an application thereof. Background Art
[0002] The development of flexible wearable electronic devices brings new challenges to their energy devices. Traditional batteries are vulnerable to external forces, leading to structural safety problems, and further causing irreversible damages such as thermal runaway and liquid leakage. Therefore, flexible devices have high requirements for flexible batteries, which need to overcome deformation problems while maintaining electrochemical performance.
[0003] In flexible devices, when the energy storage device is affected by external forces, the electrode and the electrolyte will be stratified, increasing the interfacial potential barrier and affecting the electrochemical performance of the battery. Taking the flexible zinc-air battery as an example, a qualified flexible cathode should have good electrical conductivity, appropriate porosity, appropriate hydrophilicity and hydrophobicity to form a stable three-phase interface. The cathode of the zinc-air battery consists of a current collector (for charge transfer), an air diffusion layer (for oxygen transfer), and a catalyst (for reducing the reaction energy barrier). Carbon cloth is often used as the current collection layer and the gas diffusion layer.
[0004] However, the existing air electrodes of zinc-air batteries have the following technical problems. Firstly, there is cathode overflow. Liquid water flows downward from the catalytic layer and the diffusion layer into the nearby holes, increasing the resistance of gas passing through this area. Secondly, there is catalyst loss. As a simple adhesion structure of the current collection layer and the gas diffusion layer, the carbon cloth causes the catalyst layer and the electrolyte layer to slip under external forces, resulting in catalyst loss; after the battery is used, the micropores in the air cathode layer and the cathode channel are severely blocked, and a large number of catalyst particles are lost. Finally, there is poor interfacial compatibility. The high interfacial impedance between the electrode and the hydrogel electrolyte leads to large electron transfer and diffusion resistance from the electrolyte to the electrode. Summary of the Invention
[0005] In order to overcome the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide an air electrode with an integrated structure, a preparation method thereof, and an application thereof, so as to solve the technical problems of cathode overflow, catalyst loss, and poor interfacial compatibility existing in the air electrodes of existing zinc-air batteries.
[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:
[0007] The present invention provides a preparation method of an air electrode with an integrated structure, including the following steps:
[0008] Dissolve polyvinyl alcohol in distilled water to prepare an aqueous polyvinyl alcohol solution; sequentially add potassium hydroxide and zinc acetate to the aqueous polyvinyl alcohol solution and stir to dissolve, to obtain a gel electrolyte solution; freeze and then thaw the gel electrolyte solution for several times to obtain a PVA gel electrolyte;
[0009] Carbon nanotubes are added to an aqueous solution of polyvinyl alcohol to prepare a carbon nanotube-PVA precursor solution. The carbon nanotube-PVA precursor solution is aspirated and dropped onto a PVA gel electrolyte, frozen and then thawed, and repeated several times to prepare an integrated air electrode carrier.
[0010] Platinum carbon and ruthenium oxide are wetted with absolute ethanol, and then ground into a film with a polytetrafluoroethylene emulsion to prepare a transparent film-like catalyst. The transparent film-like catalyst is coated on the upper surface of the integrated air electrode carrier to prepare an integrated air electrode.
[0011] In one embodiment, the mass ratio of polyvinyl alcohol to distilled water is (3-5):27.
[0012] In one embodiment, the dosage ratio of the aqueous solution of polyvinyl alcohol, potassium hydroxide and zinc acetate in the gel electrolyte solution is 30 mL: 1.5-3 g: 0.8-1.2 g.
[0013] In one embodiment, the dosage ratio of the aqueous solution of polyvinyl alcohol and carbon nanotubes in the carbon nanotube-PVA precursor solution is 30 mL: 0.1-0.2 g.
[0014] In one embodiment, the freezing temperature of the gel electrolyte solution is -20 to -30 °C; the number of repetitions of freezing and thawing of the gel electrolyte solution is not less than 3 times, and the freezing time is not less than 3 h; the freezing temperature of the carbon nanotube-PVA precursor solution is -20 to -30 °C; the number of repetitions of freezing and thawing of the carbon nanotube-PVA precursor solution is not less than 3 times, and the freezing time is not less than 3 h.
[0015] In one embodiment, the dosage of the carbon nanotube-PVA precursor solution is 2-4 mL.
[0016] In one embodiment, the dosage of platinum carbon is 0.01-0.015 g; the mass of ruthenium oxide is 0.01-0.015 g.
[0017] In one embodiment, the dosage of absolute ethanol is 0.15-0.25 mL; the dosage of the polytetrafluoroethylene emulsion is 0.2-0.3 mL.
[0018] The present invention also provides an integrated air electrode prepared by the preparation method of the integrated air electrode according to the above, and the air electrode includes a PVA gel electrolyte, an air electrode carrier and a transparent film-like catalyst sequentially arranged from bottom to top.
[0019] The present invention also provides the application of the integrated air electrode prepared by the preparation method of the integrated air electrode as described above in a zinc-air battery.
[0020] Compared with the prior art, the present invention has the following beneficial effects:
[0021] The present invention provides a preparation method for an air electrode with an integrated structure. In a traditional air electrode, a catalyst is supported on carbon cloth. Due to its simple adhesion structure, under the action of external force, the catalyst layer and the electrolyte layer will slip, resulting in catalyst loss. At the same time, after the battery is used, the micropores in the air cathode layer and the cathode channel are severely blocked, which will also cause a large amount of catalyst particles to be lost. However, in the air electrode of the present invention, polytetrafluoroethylene as the base material promotes the film formation of platinum-carbon and ruthenium oxide, forming a stable catalyst film. This film formation method enables the catalyst to firmly adhere to the electrode, effectively preventing the slipping of the catalyst layer and the electrolyte layer under the action of external force, avoiding catalyst loss, and thus solving the problem of poor catalytic effect caused by catalyst loss. There is a problem of poor interfacial compatibility in the air electrode of the existing zinc-air battery. The high interfacial impedance between the electrode and the hydrogel electrolyte results in large electron transfer and diffusion resistance from the electrolyte to the electrode. The traditional flexible zinc-air battery generally has a sandwich structure, and interlayer slipping will occur under the influence of external force, further affecting the device performance. The integrated air electrode structure of the present invention combines the air electrode with the gel electrolyte, and both the air electrode and the gel electrolyte are prepared by PVA through the cyclic "freezing-thawing method". Through hydrogen bonding, the interfacial compatibility between the electrolyte and the electrode is significantly improved, and the interface of the assembled flexible zinc-air battery is firmly bonded. This integrated structure not only solves the problem of high interfacial impedance but also improves the cycle stability of the battery, effectively overcoming the problem of large electron transfer and diffusion resistance caused by poor interfacial compatibility in the prior art. There is a cathode overflow phenomenon in the air electrode of the existing zinc-air battery, that is, liquid water flows downward from the catalytic layer and the diffusion layer into the nearby holes, increasing the gas passing resistance in this area. In the present invention, polytetrafluoroethylene as the base material promotes the film formation of platinum-carbon and ruthenium oxide in the air electrode to form a catalyst film. Polytetrafluoroethylene has hydrophobicity, and this property can effectively prevent the random flow of liquid water inside the electrode, thus avoiding the situation of liquid water flowing into nearby holes, and further solving the cathode overflow problem and ensuring the smooth passage of gas in the electrode area. Description of the Drawings
[0022] Figure 1 It is a discharge diagram of a zinc-air battery applying the air electrode with the integrated structure provided by the present invention. Detailed Embodiments
[0023] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meanings understood by those skilled in the art with respect to the present invention. In case of conflict, the definitions in this specification shall prevail.
[0024] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall in no way limit the scope of the present invention, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.
[0025] In this document, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values (including integers and fractions) within the ranges.
[0026] In this document, unless otherwise specified, the terms "comprise", "include", "contain", "have", or similar expressions cover the meanings of "consist of" and "consist essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".
[0027] In this document, for the sake of brevity, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as being within the scope described in this specification.
[0028] The present invention provides a method for preparing an air electrode with an integrated structure, comprising the following steps:
[0029] Prepare an aqueous solution of polyvinyl alcohol: Dissolve polyvinyl alcohol in distilled water at 95 - 120 °C for at least 1 h, with the mass ratio of polyvinyl alcohol to distilled water being (3 - 5):27, to obtain an aqueous solution of polyvinyl alcohol.
[0030] Prepare a gel electrolyte solution: Sequentially add potassium hydroxide and zinc acetate to the aqueous solution of polyvinyl alcohol, and stir to dissolve to obtain a gel electrolyte solution. Among them, the dosage ratio of the aqueous solution of polyvinyl alcohol, potassium hydroxide, and zinc acetate is 30 mL:1.5 - 3 g:0.8 - 1.2 g.
[0031] Prepare a PVA gel electrolyte: Freeze the gel electrolyte solution at -20 - 30 °C, then take it out and thaw it, repeat this process no less than 3 times, with the freezing time each time being no less than 3 h, to obtain a PVA gel electrolyte.
[0032] Preparation of an integrated air electrode support: Carbon nanotubes were added to an aqueous solution of polyvinyl alcohol to obtain a carbon nanotube-PVA precursor solution. Among them, the dosage ratio of the aqueous solution of polyvinyl alcohol to carbon nanotubes was 30 mL: 0.1 - 0.2 g. 2 - 4 mL of the carbon nanotube-PVA precursor solution was aspirated and dropped onto the PVA gel electrolyte, frozen at -20 to -30 °C, then taken out and thawed. This process was repeated no less than 3 times, and the freezing time each time was no less than 3 h to obtain the integrated air electrode support.
[0033] Preparation of a transparent film catalyst: Platinum carbon and ruthenium oxide were wetted with absolute ethanol. The dosage of platinum carbon was 0.01 - 0.015 g, and the dosage of ruthenium oxide was 0.01 - 0.015 g. Poly tetrafluoroethylene emulsion was added and ground into a film. The dosage of absolute ethanol was 0.15 - 0.25 mL, and the dosage of poly tetrafluoroethylene emulsion was 0.2 - 0.3 mL to obtain the transparent film catalyst.
[0034] Preparation of an integrated air electrode: The transparent film catalyst was coated on the upper surface of the integrated air electrode support to obtain the integrated air electrode.
[0035] The present invention also provides an integrated air electrode prepared by the above preparation method, including a PVA gel electrolyte, an air electrode support, and a transparent film catalyst arranged in sequence from bottom to top.
[0036] The above integrated air electrode can be applied to a zinc-air battery.
[0037] The following further elaborates the present invention in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.
[0038] The following embodiments use conventional instrument equipment in the art. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.
[0039] Example 1
[0040] This embodiment provides a preparation method of an integrated air electrode, including the following steps:
[0041] Step 1: Mix 3.0 g of polyvinyl alcohol and 27.0 g of distilled water in a three-necked flask, heat to 95° C., and stir for 1 hour to prepare a polyvinyl alcohol aqueous solution;
[0042] Step 2: Add 1.5 g potassium hydroxide to 30 mL polyvinyl alcohol aqueous solution, and after the solid is completely dissolved, add 0.8 g zinc acetate and stir thoroughly until the zinc acetate is dissolved to obtain a gel electrolyte solution; draw the gel electrolyte solution into a mold and freeze it at -20 to -30°C for 3 hours, then take it out and thaw it, repeat 3 times to obtain a PVA gel electrolyte;
[0043] Step 3: Add 0.1 g of carbon nanotubes to 30 mL of polyvinyl alcohol aqueous solution, stir evenly to obtain a carbon nanotube-PVA precursor solution, take 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte, freeze it at -20 to -30 ° C for 3 hours, then take it out and thaw it, repeat 3 times to obtain an integrated air electrode carrier;
[0044] Step 4: Take 0.01 g of platinum carbon and 0.01 g of ruthenium oxide respectively, grind them in an agate mortar, wet them with 0.15 mL of anhydrous ethanol, and then add 0.2 mL of polytetrafluoroethylene emulsion to grind into a film to obtain a transparent film catalyst;
[0045] Step 5: Coat the transparent film catalyst on the upper surface of the integrated air electrode carrier to prepare the air electrode, thereby obtaining an air electrode with an integrated structure.
[0046] Example 2
[0047] A method for preparing an air electrode with an integrated structure comprises the following steps:
[0048] Step 1: Add 3.0 g of polyvinyl alcohol and 27.0 g of distilled water into a three-necked flask, mix, heat to 120° C., and stir for 1 hour to obtain a polyvinyl alcohol aqueous solution;
[0049] Step 2: Add 1.5 g potassium hydroxide to 30 mL polyvinyl alcohol aqueous solution, and after the solid is completely dissolved, add 0.8 g zinc acetate and stir thoroughly until the zinc acetate is dissolved to obtain a gel electrolyte solution; draw the gel electrolyte solution into a mold and freeze it at -20 to -30°C for 3 hours, then take it out and thaw it, repeat 3 times to obtain a PVA gel electrolyte;
[0050] Step 3: Add 0.1 g of carbon nanotubes to 30 mL of polyvinyl alcohol aqueous solution, stir evenly to obtain a carbon nanotube-PVA precursor solution, take 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte, freeze it at -20 to -30 ° C for 3 hours, then take it out and thaw it, repeat 3 times to obtain an integrated air electrode carrier;
[0051] Step 4: Take 0.01 g of platinum carbon and 0.01 g of ruthenium oxide respectively, grind them in an agate mortar, wet them with 0.15 mL of anhydrous ethanol, and then add 0.2 mL of polytetrafluoroethylene emulsion to grind into a film to obtain a transparent film catalyst;
[0052] Step 5: Coat the transparent film catalyst on the upper surface of the integrated air electrode carrier to prepare the air electrode, thereby obtaining an air electrode with an integrated structure.
[0053] Example 3
[0054] A method for preparing an air electrode with an integrated structure comprises the following steps:
[0055] Step 1: Add 3.0 g of polyvinyl alcohol and 27.0 g of distilled water into a three-necked flask, mix, heat to 95° C., and stir for 1 hour to obtain a polyvinyl alcohol aqueous solution;
[0056] Step 2: Add 2 g of potassium hydroxide to 30 mL of polyvinyl alcohol aqueous solution, and after the solid is completely dissolved, add 1.0 g of zinc acetate and stir thoroughly until the zinc acetate is dissolved to obtain a gel electrolyte solution; draw the gel electrolyte solution into a mold and freeze it at -20 to -30 ° C for 3 hours, then take it out and thaw it, repeat 3 times to obtain a PVA gel electrolyte;
[0057] Step 3: Add 0.15 g of carbon nanotubes to 30 mL of polyvinyl alcohol aqueous solution, stir evenly to obtain a carbon nanotube-PVA precursor solution, take 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte, freeze it at -20 to -30 ° C for 3 hours, then take it out and thaw it, repeat 3 times to obtain an integrated air electrode carrier;
[0058] Step 4: Take 0.01 g of platinum carbon and 0.01 g of ruthenium oxide respectively, grind them in an agate mortar, wet them with 0.15 mL of anhydrous ethanol, and then add 0.2 mL of polytetrafluoroethylene emulsion to grind into a film to obtain a transparent film catalyst;
[0059] Step 5: Coat the transparent film catalyst on the upper surface of the integrated air electrode carrier to prepare the air electrode, thereby obtaining an air electrode with an integrated structure.
[0060] Example 4
[0061] A method for preparing an air electrode with an integrated structure comprises the following steps:
[0062] Step 1: Add 3.0 g of polyvinyl alcohol and 27.0 g of distilled water into a three-necked flask, mix, heat to 95° C., and stir for 1 hour to obtain a polyvinyl alcohol aqueous solution;
[0063] Step 2: Add 3 g of potassium hydroxide to 30 mL of an aqueous solution of polyvinyl alcohol. After the solid is completely dissolved, add 1.0 g of zinc acetate and stir well until the zinc acetate is dissolved to obtain a gel electrolyte solution. Aspirate the gel electrolyte solution into a mold, freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain a PVA gel electrolyte.
[0064] Step 3: Add 0.2 g of carbon nanotubes to 30 mL of an aqueous solution of polyvinyl alcohol, stir evenly to obtain a carbon nanotube-PVA precursor solution. Aspirate 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte. Freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain an integrated air electrode carrier.
[0065] Step 4: Weigh 0.01 g of platinum carbon and 0.015 g of ruthenium oxide into an agate mortar, grind them, moisten them with 0.15 mL of absolute ethanol, then add 0.2 mL of polytetrafluoroethylene emulsion and grind to form a film to obtain a transparent film-like catalyst.
[0066] Step 5: Coat the transparent film-like catalyst on the upper surface of the integrated air electrode carrier to obtain an air electrode, and an integrated air electrode is prepared.
[0067] Example 5
[0068] A preparation method of an integrated air electrode includes the following steps:
[0069] Step 1: Add 3.0 g of polyvinyl alcohol and 27.0 g of distilled water to a three-necked flask, mix them, heat up to 95 °C, and stir for 1 h to obtain an aqueous solution of polyvinyl alcohol.
[0070] Step 2: Add 2.5 g of potassium hydroxide to 30 mL of the aqueous solution of polyvinyl alcohol. After the solid is completely dissolved, add 1.2 g of zinc acetate and stir well until the zinc acetate is dissolved to obtain a gel electrolyte solution. Aspirate the gel electrolyte solution into a mold, freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain a PVA gel electrolyte.
[0071] Step 3: Add 0.1 g of carbon nanotubes to 30 mL of the aqueous solution of polyvinyl alcohol, stir evenly to obtain a carbon nanotube-PVA precursor solution. Aspirate 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte. Freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain an integrated air electrode carrier.
[0072] Step 4: Weigh 0.01 g of platinum carbon and 0.015 g of ruthenium oxide into an agate mortar, grind them, moisten them with 0.15 mL of absolute ethanol, then add 0.2 mL of polytetrafluoroethylene emulsion and grind to form a film to obtain a transparent film-like catalyst.
[0073] Step Five: Coat the upper surface of the integrated air electrode support with the transparent film catalyst to obtain the air electrode, and obtain the integrated air electrode structure.
[0074] Example 6
[0075] A preparation method of an integrated air electrode structure includes the following steps:
[0076] Step One: Add 4.0 g of polyvinyl alcohol and 27.0 g of distilled water into a three-necked flask for mixing, heat up to 120 °C, and stir for 1 h to obtain an aqueous polyvinyl alcohol solution;
[0077] Step Two: Add 2.5 g of potassium hydroxide into 30 mL of the aqueous polyvinyl alcohol solution. After the solid is completely dissolved, add 1.2 g of zinc acetate, stir well until the zinc acetate is dissolved to obtain a gel electrolyte solution; Absorb the gel electrolyte solution into a mold, freeze it at -20 to -30 °C for 3 h and then take it out to thaw, repeat 3 times to obtain the PVA gel electrolyte;
[0078] Step Three: Add 0.1 g of carbon nanotubes into 30 mL of the aqueous polyvinyl alcohol solution, stir evenly to obtain a carbon nanotube-PVA precursor solution. Absorb 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte, freeze it at -20 to -30 °C for 3 h and then take it out to thaw, repeat 3 times to obtain the integrated air electrode support;
[0079] Step Four: Respectively take 0.01 g of platinum-carbon and 0.01 g of ruthenium oxide into an agate mortar for grinding, moisten it with 0.15 mL of absolute ethanol, and then add 0.2 mL of polytetrafluoroethylene emulsion to grind into a film to obtain the transparent film catalyst;
[0080] Step Five: Coat the upper surface of the integrated air electrode support with the transparent film catalyst to obtain the air electrode, and obtain the integrated air electrode structure.
[0081] Example 7
[0082] A preparation method of an integrated air electrode structure includes the following steps:
[0083] Step One: Add 5.0 g of polyvinyl alcohol and 27.0 g of distilled water into a three-necked flask for mixing, heat up to 120 °C, and stir for 1 h to obtain an aqueous polyvinyl alcohol solution;
[0084] Step 2: Add 3 g of potassium hydroxide to 30 mL of an aqueous solution of polyvinyl alcohol. After the solid is completely dissolved, add 1.2 g of zinc acetate and stir well until the zinc acetate is dissolved to obtain a gel electrolyte solution. Aspirate the gel electrolyte solution into a mold, freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain a PVA gel electrolyte;
[0085] Step 3: Add 0.2 g of carbon nanotubes to 30 mL of an aqueous solution of polyvinyl alcohol, stir evenly to obtain a carbon nanotube-PVA precursor solution. Aspirate 2 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte. Freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain an integrated air electrode carrier;
[0086] Step 4: Weigh 0.015 g of platinum carbon and 0.015 g of ruthenium oxide into an agate mortar, grind them, moisten them with 0.15 mL of absolute ethanol, and then add 0.2 mL of polytetrafluoroethylene emulsion and grind to form a film to obtain a transparent film-like catalyst;
[0087] Step 5: Coat the transparent film-like catalyst on the upper surface of the integrated air electrode carrier to obtain an air electrode, and an integrated air electrode is prepared.
[0088] Example 8
[0089] A preparation method of an integrated air electrode includes the following steps:
[0090] Step 1: Add 5.0 g of polyvinyl alcohol and 27.0 g of distilled water to a three-necked flask, mix them, heat up to 120 °C, and stir for 1 h to obtain an aqueous solution of polyvinyl alcohol;
[0091] Step 2: Add 3 g of potassium hydroxide to 30 mL of an aqueous solution of polyvinyl alcohol. After the solid is completely dissolved, add 1.2 g of zinc acetate and stir well until the zinc acetate is dissolved to obtain a gel electrolyte solution. Aspirate the gel electrolyte solution into a mold, freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain a PVA gel electrolyte;
[0092] Step 3: Add 0.2 g of carbon nanotubes to 30 mL of an aqueous solution of polyvinyl alcohol, stir evenly to obtain a carbon nanotube-PVA precursor solution. Aspirate 4 mL of the carbon nanotube-PVA precursor solution and drop it onto the PVA gel electrolyte. Freeze it at -20 to -30 °C for 3 h, then take it out and thaw it. Repeat this process 3 times to obtain an integrated air electrode carrier;
[0093] Step 4: Weigh 0.015 g of platinum carbon and 0.015 g of ruthenium oxide into an agate mortar, grind them, moisten them with 0.25 mL of absolute ethanol, and then add 0.3 mL of polytetrafluoroethylene emulsion and grind to form a film to obtain a transparent film-like catalyst;
[0094] Step 5: Coat the transparent film-like catalyst on the upper surface of the integrated air electrode carrier to obtain an air electrode, and obtain an integrated air electrode structure.
[0095] For the integrated air electrode structure obtained in the present invention, the integrated air electrode structure combining the air electrode and the gel electrolyte solves the problem of high interfacial impedance. Since both the air electrode and the gel electrolyte matrix are prepared by the cyclic "freezing-thawing method" with PVA, and the two are bonded by hydrogen bonds, the interfacial compatibility between the electrolyte and the electrode is improved, making the interface combination of the assembled flexible zinc-air battery very firm, reducing the slippage between the catalyst layer and the electrolyte layer, and improving the cycle stability of the battery. The traditional air electrode is composed of a carbon cloth loaded with a catalyst. This air electrode promotes the film formation of platinum-carbon and ruthenium oxide through the base material polytetrafluoroethylene to form a catalyst film. On the one hand, it prevents the loss of the catalyst, resulting in poor catalytic effect. At the same time, polytetrafluoroethylene has hydrophobicity, effectively solving the problem of cathode overflow.
[0096] In order to characterize the performance of the integrated air electrode structure, the integrated air electrode structures synthesized in Examples 1 to 8 were tested for discharge feasibility, indicating that they can work normally, and relevant electrochemical performance tests were carried out.
[0097] The specific steps of the above discharge feasibility test are as follows: Assemble a zinc-air battery by sequentially assembling a zinc sheet, an integrated air electrode, and a nickel foam, and use a BlueTEC battery test system to conduct a discharge test with a discharge current of 2 mA until the battery fails. The results are as Figure 1 shown. From the discharge curve of the integrated air electrode-zinc-air battery, the discharge capacity can be obtained as 670 mAhg -1 .
[0098] Experiments show that the integrated air electrode structure can be discharged normally and has the potential to continuously optimize its electrochemical performance. It is an integrated air electrode structure with broad application prospects.
[0099] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.
Claims
1. A method for preparing an air electrode with an integrated structure, characterized in that: The following steps are involved: The polyvinyl alcohol is dissolved in distilled water to prepare a polyvinyl alcohol aqueous solution; potassium hydroxide and zinc acetate are sequentially added to the polyvinyl alcohol aqueous solution and stirred to dissolve to prepare a gel electrolyte solution; the gel electrolyte solution is frozen and then thawed, and the process is repeated several times to prepare a PVA gel electrolyte; Adding carbon nanotubes to a polyvinyl alcohol aqueous solution to prepare a carbon nanotube-PVA precursor solution, taking the carbon nanotube-PVA precursor solution and dropping it onto a PVA gel electrolyte, freezing and thawing, repeating several times, to prepare an integrated air electrode carrier; Platinum carbon and ruthenium oxide are wetted with anhydrous ethanol, and then polytetrafluoroethylene emulsion is added to grind into a film to prepare a transparent film catalyst; the transparent film catalyst is coated on the upper surface of an integrated air electrode carrier to prepare an air electrode with an integrated structure.
2. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The mass ratio of the polyvinyl alcohol to distilled water is (3-5):
27.
3. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The amount ratio of the polyvinyl alcohol aqueous solution, potassium hydroxide and zinc acetate in the gel electrolyte solution is 30 mL: 1.5-3 g: 0.8-1.2 g.
4. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The usage ratio of the polyvinyl alcohol aqueous solution and the carbon nanotubes in the carbon nanotube-PVA precursor solution is 30 mL: 0.1-0.2 g.
5. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The freezing temperature of the gel electrolyte solution is -20 to -30°C; the freezing and thawing of the gel electrolyte solution is repeated no less than 3 times, and the freezing time is no less than 3 hours; the freezing temperature of the carbon nanotube-PVA precursor solution is -20 to -30°C; the freezing and thawing of the carbon nanotube-PVA precursor solution is repeated no less than 3 times, and the freezing time is no less than 3 hours.
6. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The amount of the carbon nanotube-PVA precursor solution used is 2 to 4 mL.
7. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The amount of the platinum carbon is 0.01 to 0.015 g; the mass of the ruthenium oxide is 0.01 to 0.015 g.
8. The method for preparing an air electrode with an integrated structure according to claim 1, characterized in that: The dosage of the anhydrous ethanol is 0.15-0.25 mL; the dosage of the polytetrafluoroethylene emulsion is 0.2-0.3 mL.
9. An air electrode with an integrated structure obtained by the method for preparing an air electrode with an integrated structure according to any one of claims 1 to 8, characterized in that: It includes a PVA gel electrolyte, an air electrode carrier and a transparent film catalyst which are arranged in sequence from bottom to top.
10. Use of the air electrode with an integrated structure obtained by the method for preparing the air electrode with an integrated structure according to any one of claims 1 to 8 in a zinc-air battery.