Polyacrylamide-polyacrylic acid conductive hydrogel as well as preparation method and application thereof

Abstract

The invention discloses polyacrylamide-polyacrylic acid conductive hydrogel as well as a preparation method and application thereof. According to the hydrogel, acrylamide and polyacrylic acid are used as main monomers, N, N '-methylene bisacrylamide is used as a cross-linking agent, ammonium persulfate is used as an initiator, and a three-dimensional network structure is formed through photo-induced polymerization under the condition of purple light irradiation. Then, the prepared hydrogel is soaked in a mixed electrolyte composed of potassium hydroxide and zinc acetate, and the ionic conductivity is improved. The obtained conductive hydrogel has excellent flexibility, conductivity and mechanical stability, and can be directly applied to an electrolyte layer of a flexible zinc-air battery. The flexible zinc-air battery can realize high-current-density charging and discharging, and is suitable for the scenes of LED lamp lightening, micro unmanned aerial vehicle power supply and the like. The method is simple in preparation process, low in cost and good in process repeatability, and has a wide practical application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolyte functional materials, in particular to polyacrylamide-polyacrylic acid conductive hydrogel and a preparation method and application thereof. Background Art

[0002] Flexible zinc-air batteries are a new type of battery that uses oxygen from air as the positive active material and metallic zinc as the negative active material. This type of battery has a higher energy density and is more environmentally friendly than traditional lead-acid batteries. It also offers excellent flexibility, ductility, and comfort, making it a promising candidate for applications in flexible electronics, such as wearable electronics and flexible displays.

[0003] As a three-dimensional hydrophilic network structure material, polymer hydrogel has excellent water absorption and water retention. After full swelling, it can reach a mass several times its dry weight. After being soaked in electrolyte, it can be given a certain ionic conductivity. Therefore, it has important application potential in flexible electronic devices.

[0004] However, despite their excellent self-adhesion, water solubility, and biocompatibility, traditional polyacrylamide hydrogels rely primarily on weak hydrogen bonding and lack abundant functional groups for forming cross-linked structures with metal ions. This results in poor electrical conductivity, severely limiting their application in high-performance flexible energy storage devices. Therefore, there is an urgent need to develop a composite hydrogel material with excellent electrical conductivity, good mechanical flexibility, and stable structure to meet the demand for high-performance electrolyte materials in flexible zinc-air batteries. Summary of the Invention

[0005] The purpose of the present invention is to provide a polyacrylamide-polyacrylic acid conductive hydrogel and its preparation method and application, which has good flexibility, conductivity and structural stability, and solves the problems of poor conductivity and limited application of existing polyacrylamide gel.

[0006] To achieve the above object, the present invention provides the following technical solution: polyacrylamide-polyacrylic acid conductive hydrogel, comprising the following components:

[0007] Acrylamide monomer;

[0008] Polyacrylic acid;

[0009] cross-linking agent N,N'-methylenebisacrylamide;

[0010] Initiator ammonium persulfate;

[0011] electrolyte;

[0012] Water solvent;

[0013] Wherein, the electrolyte is a mixture of potassium hydroxide solution and zinc acetate solution.

[0014] Preferably, the components are composed of the following mass percentages:

[0015] Acrylamide: 5%-20%;

[0016] Polyacrylic acid: 0.5%-5%;

[0017] Cross-linking agent N,N'-methylenebisacrylamide: 0.15%-0.3%;

[0018] Initiator ammonium persulfate: 2%-3%;

[0019] Electrolyte: 5%-20%;

[0020] The balance is water;

[0021] The electrolyte consists of the following components: potassium hydroxide solution with a concentration of 6 mol / L;

[0022] Zinc acetate solution, concentration is 0.3 mol / L.

[0023] The preparation method of polyacrylamide-polyacrylic acid conductive hydrogel comprises the following steps:

[0024] Step S1, preparing an organic monomer mixed solution: dissolving acrylamide monomer and polyacrylic acid in water, stirring evenly, and adjusting the pH value of the solution to 8-9;

[0025] Step S2, preparing a crosslinking and initiation system: preparing an N,N'-methylenebisacrylamide crosslinker solution and an ammonium persulfate initiator solution respectively, and adding them to the mixed solution obtained in step S1 in a predetermined proportion, and stirring evenly;

[0026] Step S3, preparing a hydrogel by photopolymerization: injecting the mixed solution obtained in step S2 into a polytetrafluoroethylene mold, and irradiating it with a 365nm ultraviolet lamp for 15 minutes at room temperature to complete the photoinduced polymerization reaction and obtain a hydrogel molded body;

[0027] Step S4, soaking in adsorption electrolyte: placing the hydrogel obtained in step S3 in a mixed electrolyte of potassium hydroxide and zinc acetate, and fully soaking for more than 24 hours to obtain polyacrylamide-polyacrylic acid conductive hydrogel.

[0028] Preferably, step S1 includes the following sub-steps:

[0029] S11, dissolving the organic monomer: adding 5%-20% by mass of acrylamide monomer and 0.5%-5% by mass of polyacrylic acid to deionized water, and mixing with magnetic stirring for 20-30 minutes until completely dissolved;

[0030] S12. pH adjustment: Use potassium hydroxide solution to adjust the pH value of the mixed solution to the range of 8-9 to ensure that the polymerization reaction environment is weakly alkaline;

[0031] S13, homogenization: After completing the pH adjustment, continue magnetic stirring for 10 minutes to ensure that the solution is homogeneous and free of precipitation.

[0032] Preferably, step S2 includes the following sub-steps:

[0033] S21, crosslinker solution preparation: weigh the crosslinker N,N'-methylenebisacrylamide and prepare a 0.15%-0.3% aqueous solution;

[0034] S22. Preparation of initiator solution: Weigh ammonium persulfate and prepare a 2%-3% aqueous solution;

[0035] S22a, the amount of ammonium persulfate added is 2%-3% of the mass of the acrylamide monomer;

[0036] S23, adding and stirring: sequentially adding the initiator solution and the crosslinker solution to the organic monomer mixture obtained in step S1, and magnetically stirring for 10-20 minutes;

[0037] S24. Let the solution stand for stabilization: After stirring, let the mixed solution stand for 5 minutes to eliminate bubbles and set aside.

[0038] Preferably, step S3 includes the following sub-steps:

[0039] S31, mold loading: slowly pour the mixed solution obtained in step S2 into a polytetrafluoroethylene mold, and control the liquid level to be 80%-90% of the mold height;

[0040] S32, photopolymerization: irradiate with a 365 nm ultraviolet lamp at room temperature for 15 minutes to complete the photoinduced polymerization reaction and form a preliminary hydrogel structure;

[0041] S33. Demolding and removal: After the polymerization is completed, slowly remove the hydrogel to avoid damage caused by mechanical stress.

[0042] Preferably, step S4 includes the following sub-steps:

[0043] S41, electrolyte preparation: prepare 6 mol / L potassium hydroxide solution and 0.3 mol / L zinc acetate solution respectively, and mix them in a volume ratio of 9:1 to prepare an electrolyte;

[0044] S42, soaking the hydrogel: soaking the hydrogel obtained in step S3 in the mixed electrolyte for no less than 24 hours until the gel is completely saturated with adsorption;

[0045] S43. Liquid absorption monitoring: Weigh the hydrogel every 6 hours. When the change in the liquid absorption mass of the hydrogel is less than 2%, the liquid absorption is confirmed to be completed.

[0046] The application of polyacrylamide-polyacrylic acid conductive hydrogel includes the following steps:

[0047] a) cutting the polyacrylamide-polyacrylic acid conductive hydrogel into sheets with a size of 2 cm×2 cm;

[0048] b) placing the hydrogel sheet between the zinc plate negative electrode and the air electrode positive electrode to form an electrolyte layer;

[0049] c) using nickel tabs to connect the lead-out terminals of the zinc plate negative electrode and the air electrode positive electrode respectively;

[0050] d) wrapping the above components in a plastic bag or packaging film and sealing them at a temperature between 80° C. and 100° C.;

[0051] e) forming a zinc-air battery unit with a flexible structure and complete packaging, which is used to power subsequent flexible electronic devices.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. The present invention enhances the conductive properties by introducing polyacrylic acid, constructs a multifunctional network structure, and improves the hydrogel's electrolyte loading capacity and ion migration efficiency;

[0054] 2. By introducing the photoinitiated polymerization process, the preparation process is mild, efficient and suitable for large-scale continuous production;

[0055] 3. The prepared hydrogel works synergistically with potassium hydroxide / zinc acetate electrolyte to meet the high current density working requirements of flexible zinc-air batteries for the electrolyte layer;

[0056] 4. The conductive hydrogel of the present invention has a stable structure and can realize LED lighting test and micro-UAV flight power supply, showing excellent practical application performance and promotion value. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1a This is a sample diagram of the hydrogel after preparation in Example 1 of the present invention;

[0058] Figure 1b This is a sample diagram of the hydrogel in Example 1 of the present invention after being soaked in the electrolyte;

[0059] Figure 2 It is the cycle charge and discharge time of the zinc-air battery in Example 2 of the present invention.

[0060] Figure 3This is a power supply test for the zinc-air battery LED lamp in Example 2 of the present invention.

[0061] Figure 4 This is a test diagram of the zinc-air battery drone power supply in Example 3 of the present invention.

[0062] Figure 5 This is the SEM image of the hydrogel in Example 1 of the present invention;

[0063] Figure 6 This is a flow chart for preparing the polyacrylamide-polyacrylic acid conductive hydrogel of the present invention;

[0064] Figure 7 This is a flow chart of the electrolyte preparation and hydrogel soaking process of the present invention;

[0065] Figure 8 This is a flow chart of the flexible zinc-air battery packaging process of the present invention. DETAILED DESCRIPTION

[0066] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0067] Please refer to Figures 1 to Figure 8 The present invention provides a technical solution: polyacrylamide-polyacrylic acid conductive hydrogel, comprising the following components:

[0068] Acrylamide monomer;

[0069] Polyacrylic acid;

[0070] cross-linking agent N,N'-methylenebisacrylamide;

[0071] Initiator ammonium persulfate;

[0072] electrolyte;

[0073] Water solvent;

[0074] The electrolyte is a mixture of potassium hydroxide solution and zinc acetate solution; wherein the above components are composed according to the following mass percentages:

[0075] Acrylamide: 5%-20%;

[0076] Polyacrylic acid: 0.5%-5%;

[0077] Cross-linking agent N,N'-methylenebisacrylamide: 0.15%-0.3%;

[0078] Initiator ammonium persulfate: 2%-3%;

[0079] Electrolyte: 5%-20%;

[0080] The balance is water;

[0081] The electrolyte consists of the following components: potassium hydroxide solution with a concentration of 6 mol / L;

[0082] Zinc acetate solution, concentration is 0.3 mol / L.

[0083] The preparation method of polyacrylamide-polyacrylic acid conductive hydrogel comprises the following steps:

[0084] Step S1: preparing an organic monomer mixed solution

[0085] At room temperature, polyacrylic acid and acrylamide are used as main organic monomers, and a uniform and transparent precursor solution is prepared by gradual dissolution and pH control.

[0086] S11 organic monomer dissolution

[0087] Weigh 5%-20% acrylamide powder and 0.5%-5% polyacrylic acid in the desired ratio and add them to deionized water. It is recommended to use a magnetic stirrer and stir continuously at 400 rpm for 20-30 minutes until the solution is clear and free of visible particles.

[0088] To prevent polyacrylic acid from agglomerating, add the polyacrylic acid to the water first, then slowly add acrylamide after it is fully dissolved. It is recommended to use a dripping device to control the speed to avoid flocculation caused by instantaneous high concentrations.

[0089] S1.2 pH adjustment

[0090] Slowly add the prepared 6 mol / L potassium hydroxide solution to the mixture, and use a pH meter to monitor the pH of the mixture in real time to adjust the pH to a weakly alkaline environment of 8-9. This pH range is conducive to the stable operation of the initiation system in the subsequent polymerization reaction.

[0091] During the operation, slowly add the alkali solution in batches, stirring for 30 seconds after each addition for 10 seconds to avoid local high pH that may cause monomer degradation. After the adjustment is completed, confirm that the solution is clear and transparent.

[0092] S1.3 Homogenization

[0093] After pH adjustment, continue stirring for 10 minutes to ensure uniform distribution of the solution components. The resulting organic monomer mixed solution should be free of bubbles and precipitation and slightly viscous.

[0094] After stirring, it is recommended to let it stand for 5 minutes for observation. If there are bubbles, use low-pressure vacuum to remove them to ensure the molding quality of the subsequent photopolymerization reaction.

[0095] Step S2: Configure crosslinking and initiation system

[0096] This step aims to prepare crosslinker and initiator solutions, and add them proportionally to the monomer mixture obtained in S1 to create the reaction environment required for the subsequent photopolymerization reaction.

[0097] S2.1 Crosslinker solution preparation

[0098] Weigh 0.15%-0.3% by weight of N,N'-methylenebisacrylamide (BIS) and add it to deionized water to create a standard crosslinker solution. The recommended ratio is 150-300mg of BIS per 100mL of water. Stir at room temperature until completely dissolved.

[0099] Stir at a constant speed using a magnetic stirrer for 10 minutes, and use a glass rod to confirm that no undissolved particles are visible. It is recommended that the solution be prepared and used immediately, and avoid storage for more than 12 hours.

[0100] S2.2 Initiator solution preparation

[0101] Weigh ammonium persulfate to 2%-3% of the mass of the acrylamide monomer and prepare a 2%-3% aqueous solution. For example, if the monomer mass is 6g, the initiator dosage is 120-180mg. Add deionized water and stir for 5-10 minutes until completely clear.

[0102] Ammonium persulfate is slightly oxidizing, so gloves and goggles should be worn during use; the initiator solution should be stored in a dark place and should not be left at room temperature for more than 8 hours.

[0103] S2.3 Addition and stirring

[0104] The initiator solution (first) and the crosslinker solution (latter) are sequentially added to the organic monomer mixed solution obtained in step S1, and magnetic stirring is performed for 10-20 minutes to ensure that the crosslinking system and the reaction substrate are fully mixed.

[0105] When stirring, control the rotation speed between 300-400 rpm to prevent foaming or local temperature rise in the system.

[0106] S2.4 The solution is allowed to stand still

[0107] After stirring evenly, let the system stand for 5 minutes to release any remaining microbubbles in the solution. If the operating environment allows for low pressure, a vacuum deaerator can be used to maintain a vacuum at 0.06 MPa for 2 minutes to improve the uniformity of the system.

[0108] Step S3: Photopolymerization to prepare hydrogel

[0109] In this step, the precursor reaction solution is introduced into the mold and irradiated with ultraviolet light to achieve cross-linking and curing of the organic monomers, forming a structurally stable three-dimensional hydrogel network.

[0110] S3.1 Mould loading

[0111] A polytetrafluoroethylene mold is selected as the reaction container, which has good corrosion resistance and demolding properties. The mixed solution obtained in step S2 is slowly poured into the mold, and the liquid level is controlled at 80%-90% of the total height of the mold to reserve space for volume expansion that may occur during the polymerization process.

[0112] When pouring, pour slowly along the edge of the mold to avoid trapping bubbles. It is recommended that the mold be placed on a level surface to prevent uneven gel thickness.

[0113] S3.2 Photopolymerization

[0114] Use a 365nm UV LED curing lamp to irradiate the solution in the mold at room temperature (20-25°C). The recommended irradiation time is 15 minutes, which can achieve complete polymerization and cross-linking, forming a flexible and transparent preliminary hydrogel structure.

[0115] When using LED light bars, keep the irradiation distance within 5-10 cm to ensure uniform irradiation intensity. For porous molds or large samples, the irradiation time can be extended to 20 minutes.

[0116] S3.3 Demolding

[0117] After polymerization is complete, wait for the gel in the mold to cool naturally to room temperature. Slowly peel it off along the mold wall to remove the intact, crack-free hydrogel. The finished product should exhibit good elasticity and a dense structure, with no bubbles or unpolymerized layers on the surface.

[0118] To prevent the gel from tearing during demolding, slightly rotate the mold or use a PTFE scraper to assist in demolding; do not use hard objects to squeeze the gel.

[0119] Step S4: Soaking the adsorption electrolyte

[0120] In this step, the formed hydrogel sample is immersed in a prepared mixed electrolyte to adsorb and enrich the ion conductor components, thereby obtaining a functional gel with excellent conductive properties.

[0121] S4.1 Electrolyte Configuration

[0122] Prepare the following two solutions respectively:

[0123] Potassium hydroxide solution: Weigh analytical grade potassium hydroxide (KOH) and dissolve it in deionized water at a concentration of 6 mol / L. Stir thoroughly until completely dissolved.

[0124] Zinc acetate solution: Weigh zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and dissolve it in deionized water at a concentration of 0.3 mol / L until fully dissolved.

[0125] The two solutions were mixed in a volume ratio of 9:1 to prepare the final electrolyte for immersion. This ratio ensures that the solution has strong ionic conductivity and metal coordination stability.

[0126] After the electrolyte is prepared, it should be left to cool to 20-25°C at room temperature to avoid shrinkage or deformation of the gel structure due to excessive temperature.

[0127] S4.2 Hydrogel Soaking

[0128] Place the polyacrylamide-polyacrylic acid hydrogel sample obtained in step S3 in a clean glass dish and pour in the prepared mixed electrolyte to ensure that the hydrogel is completely covered by the liquid.

[0129] The soaking time is controlled to be more than 24 hours;

[0130] The liquid volume should be more than 10 times the gel volume to ensure uniform ion penetration.

[0131] Instructions: Multiple gels can be laid out at intervals to avoid overlapping. To ensure adequate adsorption, the gels can be turned over every 8 hours.

[0132] S4.3 Liquid aspiration monitoring

[0133] To verify the adsorption saturation state, the gel sample can be weighed every 6 hours until the weight change is less than 2% for two consecutive weighings, which is considered to be complete.

[0134] The final conductive hydrogel should be transparent to translucent, soft in texture, slightly expanded in size compared to the dry gel, and have no crystallization or precipitates attached to the surface.

[0135] Application of polyacrylamide-polyacrylic acid conductive hydrogel in flexible zinc-air batteries

[0136] This embodiment discloses the specific steps for applying polyacrylamide-polyacrylic acid conductive hydrogel in the fabrication of flexible zinc-air batteries. Through rational assembly, a zinc-air battery cell with excellent conductivity, flexibility, and airtightness is formed, suitable for powering various flexible electronic devices.

[0137] Step a: Cutting the hydrogel sheet

[0138] The prepared polyacrylamide-polyacrylic acid conductive hydrogel sample after adsorption of saturated electrolyte is cut into rectangular sheets with a size of 2 cm×2 cm using a clean tool or laser cutting equipment.

[0139] Use sharp cutting tools (such as ceramic blades or Teflon scissors) to avoid tearing the gel or rough edges during cutting.

[0140] The gel can be slightly cooled (placed at 4°C for 15 minutes) before cutting to improve shape retention during operation.

[0141] Step b: Electrode stacking assembly

[0142] Place the cut hydrogel sheet flatly on a zinc plate (as the negative electrode), and then cover the finished air electrode on the other side of the gel sheet so that the hydrogel is sandwiched between the two electrodes to form a complete electrolyte layer.

[0143] The gel sheet must be in full contact with the zinc plate and air electrode, with no obvious gaps on the surface.

[0144] Keep the electrode sheet and gel sheet the same size or slightly larger by 0.5mm to ensure the edge airtight packaging effect.

[0145] Avoid excessive pressure on the gel during the clamping process to prevent uneven thickness of the local electrolyte layer due to gel deformation.

[0146] Step c: Nickel tab connection

[0147] Nickel strip (thickness of about 0.05mm-0.1mm) is used as the tab material, which is welded or crimped onto the terminal of the zinc plate negative electrode and the air electrode positive electrode for subsequent external circuit lead-out.

[0148] The connection area between the nickel tab and the electrode is not less than 5mm 2 , to ensure low resistance contact.

[0149] Ultrasonic welding or spot welding technology can be used to fix the nickel strip, and the welding temperature is controlled at 150℃-180℃ to avoid thermal damage to the surrounding hydrogel.

[0150] The direction of the tab lead-out should remain consistent to facilitate subsequent packaging and battery arrangement.

[0151] Step d: Component packaging

[0152] Place the completed stacked battery components in a plastic bag or high-barrier packaging film and seal them using a heat sealer. The sealing temperature is controlled in the range of 80℃-100℃.

[0153] Heat sealing pressure: 0.2MPa-0.3MPa;

[0154] Heat sealing time: 2-3 seconds;

[0155] The sealing line width is recommended to be ≥5mm to ensure good air tightness.

[0156] The recommended packaging bag material is nylon / polyethylene composite film (NY / PE) with a thickness of more than 80μm;

[0157] If high-barrier diaphragm materials are used, the service life of zinc-air batteries can be effectively extended and the impact of environmental moisture can be reduced.

[0158] Before heat sealing, make sure there is no residual air inside (vacuum or roll to exhaust appropriately);

[0159] Avoid high temperatures from melting through the packaging film during the sealing process.

[0160] Step e: Zinc-air battery cell molding and application

[0161] After completing the above steps, a fully encapsulated, flexible zinc-air battery cell is obtained. This battery cell can be directly used to power flexible electronic products such as wearable devices, micro drones, flexible displays, and smart sensors.

[0162] Static voltage (open circuit voltage)>1.2V;

[0163] Flexible bending radius is less than 5mm;

[0164] The power supply stability time can reach more than several hours, depending on the battery size and load power.

[0165] Avoid bending the battery more than 90° during use to prevent the hydrogel layer from breaking;

[0166] For long-term storage, it is recommended to store in a sealed container at low temperature (5℃-10℃) and dry environment.

[0167] The present invention will be further described below in conjunction with examples so that those skilled in the art can more clearly understand and implement the present invention. However, it should be understood that the following examples are only used to illustrate the present invention, rather than to limit the present invention. Without departing from the spirit of the present invention, the equivalent improvements and replacements made should all be encompassed within the scope of protection of the present invention. The raw materials, equipment, and operating conditions used in the examples are all commonly used or commercially available in this area unless otherwise specified, and the operating method is also conventional means in this area.

[0168] Example 1: Preparation of conductive hydrogel

[0169] The chemicals used in this example are: acrylamide, polyacrylic acid, N,N'-methylenebisacrylamide, ammonium persulfate, potassium hydroxide, zinc acetate, and deionized water.

[0170] 1) Accurately weigh 100 mg of N,N'-methylenebisacrylamide and add deionized water to make a 25 ml solution under magnetic stirring.

[0171] 2) Accurately weigh 180 mg of ammonium persulfate and add deionized water to prepare a 25 ml solution under magnetic stirring.

[0172] 3) Accurately weigh 1 ml of polyacrylic acid and 6 g of acrylamide, add deionized water and prepare a 10 ml solution under magnetic stirring.

[0173] 4) Add 2 ml of the crosslinker solution prepared in step 1) to the mixed solution in step 3), and then add 2 ml of the initiator solution prepared in step 2), and mix and stir evenly at room temperature using magnetic stirring.

[0174] 5) An appropriate amount of the mixed solution obtained in step 4) is placed in a polytetrafluoroethylene mold and irradiated with a 365 nm wavelength ultraviolet light to perform photoinduced polymerization, thereby finally obtaining a polyacrylamide-polyacrylic acid composite hydrogel.

[0175] 6) Accurately weigh 17 g of potassium hydroxide and 3.36 g of zinc acetate, add deionized water and prepare a 50 ml mixed solution under magnetic stirring. Cool until ready for use.

[0176] 7) Soaking the polyacrylamide-polyacrylic acid composite hydrogel prepared in step 5) in the mixed electrolyte in step 6) for 24 hours until the gel completely absorbs water and swells, thereby obtaining the polyacrylamide-polyacrylic acid composite conductive hydrogel.

[0177] Example 2: Assembly method of flexible zinc-air battery

[0178] This example provides a method for assembling a zinc-air battery. Chemicals used: acrylamide, polyacrylic acid, N,N'-methylenebisacrylamide, ammonium persulfate, potassium hydroxide, zinc acetate, and deionized water. Other materials: zinc plate, air electrode, nickel tab, and packaging bag. Tools: sealing machine, scissors, rubber band, and plastic packaging bag.

[0179] 1) Accurately weigh 100 mg of N,N'-methylenebisacrylamide and add deionized water to make a 25 ml solution under magnetic stirring.

[0180] 2) Accurately weigh 180 mg of ammonium persulfate and add deionized water to prepare a 25 ml solution under magnetic stirring.

[0181] 3) Accurately weigh 1 ml of polyacrylic acid and 6 g of acrylamide, add deionized water and prepare a 10 ml solution under magnetic stirring.

[0182] 4) Add 2 ml of the crosslinker solution prepared in step 1) to the mixed solution in step 3), and then add 2 ml of the initiator solution prepared in step 2), and mix and stir evenly at room temperature using magnetic stirring.

[0183] 5) An appropriate amount of the mixed solution obtained in step 4) is placed in a polytetrafluoroethylene mold and irradiated with a 365 nm wavelength ultraviolet light to perform photoinduced polymerization, thereby finally obtaining a polyacrylamide-polyacrylic acid composite hydrogel.

[0184] 6) Accurately weigh 17 g of potassium hydroxide and 3.36 g of zinc acetate, add deionized water and prepare a 50 ml mixed solution under magnetic stirring. Cool until ready for use.

[0185] 7) Soaking the polyacrylamide-polyacrylic acid composite hydrogel prepared in step 5) in the mixed electrolyte in step 6) for 24 hours until the gel completely absorbs water and swells, thereby obtaining the polyacrylamide-polyacrylic acid composite conductive hydrogel.

[0186] The obtained polyacrylamide-polyacrylic acid composite conductive hydrogel was cut into a size of 2*2 cm, and the zinc plate and air electrode were cut into the same size. The zinc-air battery was assembled using a plastic bag, a sealing machine, and a nickel tab.

[0187] Example 3: LED lighting and drone power supply test

[0188] This embodiment provides a method for assembling a zinc-air battery that can be used to illuminate LED lights and power drones. Chemicals used: acrylamide, polyacrylic acid, N,N'-methylenebisacrylamide, ammonium persulfate, potassium hydroxide, zinc acetate, and deionized water. Other materials: zinc plate, air electrode, nickel tab, and packaging bag. Tools: sealing machine, scissors, rubber band, plastic bag, LED light, and miniature drone.

[0189] 1) Accurately weigh 100 mg of N,N'-methylenebisacrylamide and add deionized water to make a 25 ml solution under magnetic stirring.

[0190] 2) Accurately weigh 180 mg of ammonium persulfate and add deionized water to prepare a 25 ml solution under magnetic stirring.

[0191] 3) Accurately weigh 1 ml of polyacrylic acid and 6 g of acrylamide, add deionized water and prepare a 10 ml solution under magnetic stirring.

[0192] 4) Add 2 ml of the crosslinker solution prepared in step 1) to the mixed solution in step 3), and then add 2 ml of the initiator solution prepared in step 2), and mix and stir evenly at room temperature using magnetic stirring.

[0193] 5) An appropriate amount of the mixed solution obtained in step 4) is placed in a polytetrafluoroethylene mold and irradiated with a 365 nm wavelength ultraviolet light to perform photoinduced polymerization, thereby finally obtaining a polyacrylamide-polyacrylic acid composite hydrogel.

[0194] 6) Accurately weigh 17 g of potassium hydroxide and 3.36 g of zinc acetate, add deionized water and prepare a 50 ml mixed solution under magnetic stirring. Cool until ready for use.

[0195] 7) Soaking the polyacrylamide-polyacrylic acid composite hydrogel prepared in step 5) in the mixed electrolyte in step 6) for 24 hours until the gel completely absorbs water and swells, thereby obtaining the polyacrylamide-polyacrylic acid composite conductive hydrogel.

[0196] Connect the assembled zinc-air battery to an LED light to perform an LED lighting experiment. Connect the assembled zinc-air batteries in series and then in parallel with a lithium battery. Use tape or rubber bands to secure the zinc-air battery to a drone to power the micro-drone.

[0197] Application Example 1: Electrochemical Performance Testing

[0198] The polyacrylamide-polyacrylic acid composite conductive hydrogel prepared in Example 1 and Example 2 was Figure 1a 、 Figure 1b As shown, the zinc plate and air electrode were cut into 2*2cm dimensions. The zinc-air battery was assembled using a plastic bag, a sealing machine, and nickel tabs. Electrochemical performance testing was performed using a Blue Electric battery testing system.

[0199] like Figure 2 As shown, the assembled flexible zinc-air battery can cycle charge and discharge for 77748 seconds (about 21.6 hours) at a current density of about 20mA / cm2, proving that it can achieve high current density charge and discharge cycles.

[0200] Application Example 2: LED Light Power Supply Test

[0201] The polyacrylamide-polyacrylic acid composite conductive hydrogels prepared in Example 1 and Example 3 were Figure 1a 、 Figure 1b As shown, cut into 2*2cm size, cut the zinc plate and air electrode into the same size, and assemble them into a zinc-air battery using medical tape and nickel tabs. By powering the LED light, the zinc-air battery LED light power supply test is realized, as shown in the figure. Figure 3 shown.

[0202] Application Example 3: Drone Flight Power Supply

[0203] The polyacrylamide-polyacrylic acid composite conductive hydrogels prepared in Example 1 and Example 3 were Figure 1a 、 Figure 1b As shown, cut into 2*2cm size, cut the zinc plate and air electrode into the same size, and assemble them into zinc-air batteries using sealing bags, laminators, and nickel tabs. The assembled zinc-air batteries can be connected in series and then in parallel with lithium batteries. Use tape or rubber bands to fix the zinc-air batteries on the drone to power the micro drone. Figure 4 shown.

[0204] Experimental Example 1: SEM morphology observation

[0205] The polyacrylamide-polyacrylic acid composite conductive hydrogel prepared in Example 1 was monitored by electron microscopy. Figure 5 From the SEM test image of the gel, it can be seen that the prepared hydrogel has an obvious three-dimensional structure.

[0206] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. Polyacrylamide-polyacrylic acid conductive hydrogel, characterized in that: Includes the following components: Acrylamide monomer; Polyacrylic acid; cross-linking agent N,N'-methylenebisacrylamide; Initiator ammonium persulfate; electrolyte; Water solvent; Wherein, the electrolyte is a mixture of potassium hydroxide solution and zinc acetate solution.

2. The polyacrylamide-polyacrylic acid conductive hydrogel according to claim 1, characterized in that: The components are composed according to the following mass percentages: Acrylamide: 5%-20%; Polyacrylic acid: 0.5%-5%; Cross-linking agent N,N'-methylenebisacrylamide: 0.15%-0.3%; Initiator ammonium persulfate: 2%-3%; Electrolyte: 5%-20%; The balance is water; The electrolyte consists of the following components: potassium hydroxide solution with a concentration of 6 mol / L; Zinc acetate solution, concentration is 0.3 mol / L.

3. A method for preparing a polyacrylamide-polyacrylic acid conductive hydrogel, for preparing the polyacrylamide-polyacrylic acid conductive hydrogel according to any one of claims 1 to 2, characterized in that: The following steps are involved: Step S1, preparing an organic monomer mixed solution: dissolving acrylamide monomer and polyacrylic acid in water, stirring evenly, and adjusting the pH value of the solution to 8-9; Step S2, preparing a crosslinking and initiation system: preparing an N,N'-methylenebisacrylamide crosslinker solution and an ammonium persulfate initiator solution respectively, and adding them to the mixed solution obtained in step S1 in a predetermined proportion, and stirring evenly; Step S3, preparing a hydrogel by photopolymerization: injecting the mixed solution obtained in step S2 into a polytetrafluoroethylene mold, and irradiating it with a 365nm ultraviolet lamp for 15 minutes at room temperature to complete the photoinduced polymerization reaction and obtain a hydrogel molded body; Step S4, soaking in adsorption electrolyte: placing the hydrogel obtained in step S3 in a mixed electrolyte of potassium hydroxide and zinc acetate, and fully soaking for more than 24 hours to obtain polyacrylamide-polyacrylic acid conductive hydrogel.

4. The method for preparing the polyacrylamide-polyacrylic acid conductive hydrogel according to claim 3, wherein: The step S1 includes the following sub-steps: S11, dissolving the organic monomer: adding 5%-20% by mass of acrylamide monomer and 0.5%-5% by mass of polyacrylic acid to deionized water, and mixing with magnetic stirring for 20-30 minutes until completely dissolved; S12. pH adjustment: Use potassium hydroxide solution to adjust the pH value of the mixed solution to the range of 8-9 to ensure that the polymerization reaction environment is weakly alkaline; S13, homogenization: After completing the pH adjustment, continue magnetic stirring for 10 minutes to ensure that the solution is homogeneous and free of precipitation.

5. The method for preparing the polyacrylamide-polyacrylic acid conductive hydrogel according to claim 3, wherein: The step S2 includes the following sub-steps: S21, crosslinker solution preparation: weigh the crosslinker N,N'-methylenebisacrylamide and prepare a 0.15%-0.3% aqueous solution; S22. Preparation of initiator solution: Weigh ammonium persulfate and prepare a 2%-3% aqueous solution; S22a, the amount of ammonium persulfate added is 2%-3% of the mass of the acrylamide monomer; S23, adding and stirring: sequentially adding the initiator solution and the crosslinker solution to the organic monomer mixture obtained in step S1, and magnetically stirring for 10-20 minutes; S24. Let the solution stand for stabilization: After stirring, let the mixed solution stand for 5 minutes to eliminate bubbles and set aside.

6. The method for preparing the polyacrylamide-polyacrylic acid conductive hydrogel according to claim 3, wherein: The step S3 includes the following sub-steps: S31, mold loading: slowly pour the mixed solution obtained in step S2 into a polytetrafluoroethylene mold, and control the liquid level to be 80%-90% of the mold height; S32, photopolymerization: irradiate with a 365 nm ultraviolet lamp at room temperature for 15 minutes to complete the photoinduced polymerization reaction and form a preliminary hydrogel structure; S33. Demolding and removal: After the polymerization is completed, slowly remove the hydrogel to avoid damage caused by mechanical stress.

7. The method for preparing the polyacrylamide-polyacrylic acid conductive hydrogel according to claim 3, wherein: The step S4 includes the following sub-steps: S41, electrolyte preparation: prepare 6 mol / L potassium hydroxide solution and 0.3 mol / L zinc acetate solution respectively, and mix them in a volume ratio of 9:1 to prepare an electrolyte; S42, soaking the hydrogel: soaking the hydrogel obtained in step S3 in the mixed electrolyte for no less than 24 hours until the gel is completely saturated with adsorption; S43. Liquid absorption monitoring: Weigh the hydrogel every 6 hours. When the change in the liquid absorption mass of the hydrogel is less than 2%, the liquid absorption is confirmed to be completed.

8. Application of polyacrylamide-polyacrylic acid conductive hydrogel, characterized by: The polyacrylamide-polyacrylic acid conductive hydrogel prepared by the polyacrylamide-polyacrylic acid conductive hydrogel preparation method according to any one of claims 3 to 7 is applied to a flexible zinc-air battery, comprising the following steps: a) cutting the polyacrylamide-polyacrylic acid conductive hydrogel into sheets with a size of 2 cm×2 cm; b) placing the hydrogel sheet between the zinc plate negative electrode and the air electrode positive electrode to form an electrolyte layer; c) using nickel tabs to connect the lead-out terminals of the zinc plate negative electrode and the air electrode positive electrode respectively; d) wrapping the above components in a plastic bag or packaging film and sealing them at a temperature between 80° C. and 100° C.; e) forming a zinc-air battery unit with a flexible structure and complete packaging, which is used to power subsequent flexible electronic devices.

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