Preparation of a Flexible Conductive High-Temperature-Resistant Hydrogel and Its Application in Flexible Zinc-Ion Batteries

Abstract

The invention discloses the preparation of a flexible conductive high-temperature resistant hydrogel and its application in a flexible zinc-ion battery. The preparation method comprises the following steps: reacting graphene oxide, ammonium cerium nitrate and NIPAM monomer to obtain GO-g-PNIPAM; then reacting P(VDF-TrFE-CTFE), Zn(OTF)2 and GO-g-PNIPAM to obtain a P(VDF-TrFE-CTFE) / GO-g-PNIPAM flexible conductive high-temperature resistant hydrogel. In the invention, grafting graphene oxide with N-isopropylacrylamide (PNIPAM) can improve the structural stability of PNIPAM and enhance the mechanical properties of the hydrogel. At the same time, the added P(VDF-TrFE-CTFE) can improve the conductivity of the hydrogel. The prepared hydrogel has good mechanical properties and high-temperature resistance and can be used in the aspect of flexible zinc-ion batteries.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible batteries, and particularly relates to the preparation of a flexible conductive high-temperature resistant hydrogel and its application in flexible zinc ion batteries. Background Art

[0002] With the rapid development of various portable and wearable electronic devices, the development of new flexible energy storage devices has become a hot topic in scientific research. Therefore, the research on batteries with high performance and bend resistance is the key to the development of wearable electronic products. Smart wearable devices and integrated electronic products need to meet the requirements of shape diversity and mobile usability. Flexible displays, flexible electronic skins, smart e-clothes, microelectromechanical systems and other applications are in various forms, and flexible electronic devices are developing towards miniaturization and lightweight.

[0003] In recent years, lithium ion batteries have been the dominant energy storage devices in the market. However, they have some disadvantages such as harsh assembly conditions, toxic organic electrolytes, insufficient safety factor, and performance degradation or function limitation under extreme conditions, which seriously hinder their application in wearable electronic products. Therefore, considering the issues and challenges in terms of economic benefits, ecological environment and safe application, researchers are committed to developing and exploring new energy storage systems, hoping to develop "green" batteries with good quality, low price and high cost performance. The research and development of high-performance rechargeable aqueous batteries has pushed the research of secondary batteries to a new stage. Due to their low cost, environmental friendliness and high safety, they can meet the requirements of large-scale energy storage systems and have gradually become a hot topic in the field of electrochemical energy storage in recent years.

[0004] Among various aqueous energy storage devices, due to the rich and low-cost zinc resources, and the new rechargeable zinc ion batteries (ZIBs) using near-neutral zinc salts as electrolytes, which are not only simple to fabricate, lower in cost, but also safe, non-toxic and have relatively high specific capacity, avoiding the risk of explosion and combustion of traditional lithium batteries, they are a better choice for flexible electronic devices. Therefore, people have great favor for zinc ion batteries. Hydrogel materials are a class of functional polymer materials with a three-dimensional polymer network structure, generally loose cross-linked polymer materials containing a small amount of solid components, and they contain a large amount of water inside, being soft and elastic. Applying them as electrolytes in aqueous zinc ion batteries will endow the batteries with both conductive performance and bendability, further improving the safety and service life of the batteries. However, traditional hydrogels have poor conductivity and are not resistant to high temperatures. Therefore, it is very important to design and synthesize polymer electrolytes with high ionic conductivity, high temperature resistance, mechanical and electrochemical properties for ZIBs. Summary of the Invention

[0005] The primary object of the present invention is to overcome the disadvantages and deficiencies of the prior art and provide a method for preparing a flexible conductive high-temperature resistant hydrogel.

[0006] Another object of the present invention is to provide the flexible conductive high-temperature resistant hydrogel prepared by the above method.

[0007] Still another object of the present invention is to provide the application of the flexible conductive high-temperature resistant hydrogel.

[0008] The object of the present invention is achieved by the following technical solutions:

[0009] A method for preparing a flexible conductive high-temperature resistant hydrogel, comprising the following steps:

[0010] (1) Synthesize graphene oxide-grafted poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0011] Ultrasonically disperse graphene oxide in water to obtain a mixed solution A; dissolve ammonium cerium nitrate in a nitric acid solution to obtain a mixed solution B; then add the mixed solution B dropwise to the mixed solution A, stir evenly to obtain a mixed solution C; then, under a protective gas atmosphere and at a temperature of 60 ± 5 °C, add NIPAM monomers to the mixed solution C for polymerization reaction. After the reaction is completed, filter and collect the reaction product, and wash to obtain GO-g-PNIPAM;

[0012] (2) Synthesize a hydrogel electrolyte

[0013] Stir and disperse GO-g-PNIPAM in N,N-dimethylformamide (DMF) to obtain a GO-g-PNIPAM suspension; dissolve P(VDF-TrFE-CTFE) and Zn(OTF)2 in N,N-dimethylformamide (DMF) to obtain a mixed solution D; then add the mixed solution D to the GO-g-PNIPAM suspension, stir and react at 40 ± 5 °C under sealed conditions, then perform ultrasonic treatment, filter and form a film, and vacuum dry to obtain a P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte, that is, the flexible conductive high-temperature resistant hydrogel.

[0014] Preferably, in step (1), the mass ratio of the graphene oxide to the ammonium cerium nitrate is 1:(1 - 10).

[0015] More preferably, in step (1), the mass ratio of the graphene oxide to the ammonium cerium nitrate is 1:4.

[0016] Preferably, in step (1), the amount of water used is calculated as 1 - 5 mL of water per milligram (mg) of graphene oxide.

[0017] More preferably, the amount of water described in step (1) is calculated based on 2 mL of water per milligram (mg) of graphene oxide.

[0018] Preferably, the water described in step (1) is preferably deionized water.

[0019] Preferably, the concentration of the nitric acid solution described in step (1) is 0.5 - 3 mol / L.

[0020] More preferably, the concentration of the nitric acid solution described in step (1) is 1 mol / L.

[0021] Preferably, the amount of the nitric acid solution described in step (1) is calculated based on 50 - 200 mL of the nitric acid solution per gram (g) of ammonium cerium nitrate.

[0022] More preferably, the amount of the nitric acid solution described in step (1) is calculated based on 100 mL of the nitric acid solution per gram (g) of ammonium cerium nitrate.

[0023] Preferably, the stirring time described in step (1) is 30 - 180 min.

[0024] More preferably, the stirring time described in step (1) is 60 min.

[0025] Preferably, the protective gas described in step (1) is nitrogen.

[0026] Preferably, the amount of the NIPAM monomer described in step (1) is calculated based on 0.1 mmol - 0.4 mmol of the NIPAM monomer per milligram (mg) of graphene oxide.

[0027] Preferably, the polymerization reaction time described in step (1) is 1 - 6 h.

[0028] More preferably, the polymerization reaction time described in step (1) is 3 h.

[0029] Preferably, the cleaning in step (1) is carried out using alcohol and N,N - dimethylformamide to remove residual monomers and free polymers.

[0030] Preferably, the stirring and dispersing time described in step (2) is 2 - 36 h.

[0031] More preferably, the stirring and dispersing time described in step (2) is 12 h.

[0032] Preferably, the mass ratio of P(VDF - TrFE - CTFE) to Zn(OTF)2 described in step (2) is (1 - 10):1.

[0033] More preferably, the mass ratio of P(VDF-TrFE-CTFE) to Zn(OTF)2 described in step (2) is 1:1.

[0034] Preferably, the weight ratio of P(VDF-TrFE-CTFE) to GO-g-PNIPAM described in step (2) is 1:0.01 - 0.1.

[0035] Preferably, the concentration of the GO-g-PNIPAM suspension described in step (2) is 80 - 100 mg / mL.

[0036] Preferably, the dosage of N,N-dimethylformamide (DMF) described in step (2) is calculated as 1 - 5 mL of N,N-dimethylformamide per gram of P(VDF-TrFE-CTFE).

[0037] More preferably, the dosage of N,N-dimethylformamide (DMF) described in step (2) is calculated as 1 - 2 mL of N,N-dimethylformamide per gram of P(VDF-TrFE-CTFE).

[0038] Preferably, the stirring reaction time described in step (2) is 2 - 18 h.

[0039] More preferably, the stirring reaction time described in step (2) is 6 h.

[0040] Preferably, the ultrasonic treatment time described in step (2) is 5 - 60 min.

[0041] More preferably, the ultrasonic treatment time described in step (2) is 10 min.

[0042] Preferably, the vacuum drying time described in step (2) is 2 - 3 days.

[0043] A flexible conductive high-temperature resistant hydrogel is prepared by the method described in any one of the above.

[0044] The application of the flexible conductive high-temperature resistant hydrogel in the preparation of flexible zinc ion batteries.

[0045] A flexible zinc ion battery uses MXene / VO2 as the positive electrode, a zinc sheet as the negative electrode, and the above flexible conductive high-temperature resistant hydrogel as the electrolyte and separator (to assemble a flexible zinc ion battery).

[0046] Preferably, the thickness of the flexible conductive high-temperature resistant hydrogel is about 1 mm.

[0047] The described MXene / VO2 is prepared by the following method: Add VO2 and MXene into water, perform ultrasonic treatment, suction filtration, and vacuum drying to obtain MXene / VO2 (the positive electrode material).

[0048] Preferably, the described VO2 is prepared by the following method:

[0049] Disperse V2O5 powder and oxalic acid into water, stir and mix at 75 ± 5 °C, then react at 180 ± 5 °C. After the reaction ends, wash and dry to obtain VO2.

[0050] Preferably, the molar ratio of the described V2O5 to oxalic acid is 1:(1 - 5).

[0051] More preferably, the molar ratio of the described V2O5 to oxalic acid is 1:3.

[0052] Preferably, the stirring time at 75 ± 5 °C is 2 - 3 h.

[0053] More preferably, the stirring time at 75 ± 5 °C is 2 h.

[0054] Preferably, the described washing is to wash alternately with deionized water and ethanol.

[0055] Preferably, the described MXene is prepared by the following method:

[0056] Add LiF and Ti3AlC2 into the HCl solution, stir and react at 35 ± 1 °C to selectively etch the Al atomic layer, wash, take the precipitate, then ultrasonically disperse the precipitate into water, centrifuge, and collect the supernatant to obtain the Ti3C2T x nanosheet solution, that is, the MXene solution.

[0057] Preferably, the mass ratio of the described LiF to Ti3AlC2 is 1:(1 - 3)

[0058] More preferably, the mass ratio of the described LiF to Ti3AlC2 is 1:1.

[0059] Preferably, the concentration of the described HCl solution is 9 mol / L.

[0060] Preferably, the dosage of the described HCl solution is calculated according to 10 - 30 mL of HCl solution per gram of LiF.

[0061] More preferably, the dosage of the described HCl solution is calculated according to 20 mL of HCl solution per gram of LiF.

[0062] Preferably, the stirring reaction time is more than 24 hours.

[0063] Preferably, the time of ultrasonic dispersion is more than 1 hour.

[0064] Preferably, the conditions for centrifugation are: centrifuging at 3500 rpm for 30 - 90 minutes.

[0065] More preferably, the conditions for centrifugation are: centrifuging at 3500 rpm for 60 minutes.

[0066] Preferably, the mass ratio of VO2 to MXene is 1:(1 - 3).

[0067] More preferably, the mass ratio of VO2 to MXene is 1:2.

[0068] Preferably, the time of ultrasonic treatment is 30 - 60 min.

[0069] More preferably, the time of ultrasonic treatment is 30 min.

[0070] In the technical solution of the present invention, poly(N-isopropylacrylamide) (PNIPAM) is a polymer containing both hydrophilic amide groups and hydrophobic isopropyl groups, having excellent thermal response function, good compatibility and tensile strength, and can be easily modified by grafting or crosslinking to endow PNIPAM with good mechanical strength, ionic conductivity and structural designability. The abundant hydroxyl groups on the surface of graphene oxide initiate polymerization with PNIPAM under the action of Ce(IV) / HNO3, and are successfully grafted with PNIPAM, fundamentally avoiding local phase separation, and at the same time introducing strong interfacial interactions to ensure the structural stability of the polymer. The introduction of the polymer P(VDF-TrFE-CTFE) with ultra-high dielectric constant can greatly promote the decomposition of zinc salts, increase the carrier concentration, and promote ion migration, thereby improving the ionic conductivity.

[0071] The present invention has the following advantages and effects compared with the prior art:

[0072] (1) In the present invention, poly(N-isopropylacrylamide) (PNIPAM) is first grafted onto graphene oxide nanosheets (GO) to obtain the GO-g-PNIPAM polymer, which improves the structural stability of PNIPAM and enhances the mechanical properties of the hydrogel. Then, the polymer P(VDF-TrFE-CTFE) with ultra-high dielectric constant is added to ensure strong electrolyte salt dissociation ability and promote ion migration, improving the conductivity of the hydrogel and greatly enhancing the electrochemical performance of the composite hydrogel.

[0073] (2) The high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel of the present invention can significantly improve the mechanical properties of the composite material by virtue of the extensive chemical bonds and strong intermolecular interactions between individual unaggregated graphene oxides and the surrounding polymer matrix.

[0074] (3) The high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel of the present invention uses Ce(Ⅳ) / HNO3 as an initiator to prepare poly(N-isopropylacrylamide)-grafted graphene oxide through in-situ polymerization, with a simple process and low cost.

[0075] (4) The properties of the high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel of the present invention are very rich. In addition to the properties of general hydrogels, adding the polymer PNIPAM with hydrophilic amide groups and hydrophobic isopropyl groups can greatly improve the high-temperature performance of the hydrogel, enabling it to work at high temperatures.

[0076] (5) Adding the polymer P(VDF-TrFE-CTFE) with an ultra-high dielectric constant to the high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel of the present invention can promote the decomposition of zinc salts and greatly improve the ionic conductivity of the hydrogel.

[0077] (6) The present invention also provides a flexible wearable rechargeable battery. VO2 is synthesized by a simple one-step hydrothermal method, and MXene / VO2 self-supporting cathode material is obtained by compounding VO2 with MXene. Using the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel prepared by the present invention as the electrolyte, a flexible high-temperature resistant aqueous zinc-ion battery is obtained, solving technical problems such as poor safety of organic electrolyte batteries and poor high-temperature performance of traditional aqueous electrolyte batteries, and providing a novel, low-cost and highly practical battery. Description of the Drawings

[0078] Figure 1 Optical picture of the flexible conductive high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPA M hydrogel prepared in Example 1.

[0079] Figure 2 Mechanical property diagrams of the flexible conductive high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPA M hydrogel prepared in Example 1 at different temperatures (placed at 25°C, 55°C, 85°C for 12 h).

[0080] Figure 3Ionic conductivity graph of the flexible, conductive, high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPA M hydrogel prepared in Example 1.

[0081] Figure 4 Cycling test graph (at a current of 1 A) at 85 °C of a zinc-ion battery prepared using the hydrogel electrolytes in Examples 1-9 and Comparative Examples 1-3.

[0082] Figure 5 Voltage graph before and after bending when the flexible, conductive, high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPA M hydrogel prepared in Example 1 is applied to a flexible battery system.

[0083] Figure 6 Power supply graph of an electronic watch when the flexible, conductive, high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPA M hydrogel prepared in Example 1 is applied to a flexible battery system. Detailed implementation manners

[0084] The present invention will be further described in detail below in conjunction with examples, but the implementation manners of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field. The test methods without specific experimental conditions specified in the following examples are usually carried out under conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention can be obtained commercially.

[0085] In the present invention, MXene / VO2 is used as the positive electrode, a zinc sheet is used as the negative electrode, and the hydrogels prepared in the examples and comparative examples are used as the electrolyte and separator, and finally a flexible zinc-ion battery is assembled. Among them, the positive electrode of the zinc-ion battery is prepared by the following method:

[0086] (1) Synthesize VO2 by a one-step hydrothermal method: Disperse 2 mmol of commercial V2O5 powder and 6 mmol of oxalic acid in 80 mL of deionized water, stir at 75 °C for 2 h, transfer to a 100 mL autoclave, react at 180 °C for 12 h, after cooling, wash the reaction product alternately with deionized water and ethanol, and finally dry in vacuum to obtain VO2.

[0087] (2) Synthesis of MXene: Add 1 g of LiF and 1 g of Ti3AlC2 to 20 mL of HCl solution (9 M), stir at 35 °C for 24 hours to selectively etch the Al atomic layer. Then wash several times with deionized water in a centrifuge until the pH reaches above 6. Disperse the wet precipitate in 80 mL of deionized water, after ultrasonic treatment for 1 h, centrifuge at 3500 rpm for 60 minutes, and collect the supernatant to obtain a uniformly dispersed Ti3C2T x(MXene) nanosheet solution (concentration: 8 - 10 mg / mL).

[0088] (3) Ultrasonicate 15 mg of VO2 and 30 mg of MXene for 30 min, then perform suction filtration and vacuum drying to obtain the MXene / VO2 self-supporting cathode material. Next, cut the MXene / VO2 cathode material into 1×1 cm squares to serve as the cathode of the flexible zinc-ion battery, with an active mass of 2 mg cm -2 .

[0089] The testing method for the flexible zinc-ion battery in the embodiments of this application: Use a Neware battery tester to perform constant current charge and discharge tests on the flexible zinc-ion battery.

[0090] The raw materials involved in the embodiments of this application are as follows: Graphene oxide (purchased from Aladdin), NIPAM monomer (purchased from Aladdin), and the terpolymer P(VDF-TrFE-CTFE) (purchased from Arkema).

[0091] Example 1

[0092] First step, synthesize poly N-isopropylacrylamide grafted graphene (GO-g-PNIPAM):

[0093] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0094] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0095] (3) Slowly add solution B dropwise to solution A and stir for 60 min to remove oxygen.

[0096] (4) Under a nitrogen atmosphere, add 1.13 g of NIPAM monomer to the solution in step (3) and stir and polymerize at 60 °C for 3 h.

[0097] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and N,N-dimethylformamide (DMF) to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0098] Second step, synthesize the hydrogel electrolyte:

[0099] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)2 in 5 mL of DMF.

[0100] ② Add 0.18 g of GO-g-PNIPAM to the solution in step ① (that is, measure the corresponding volume of the GO-g-PNIPAM suspension according to the required mass of GO-g-PNIPAM, the same below).

[0101] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte. Its optical picture is as Figure 1 shown.

[0102] Example 2

[0103] First step, synthesize graphene oxide grafted with poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0104] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0105] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0106] (3) Dropwise add solution B to solution A, stir for 60 min to remove oxygen.

[0107] (4) Under a nitrogen atmosphere, add 1.13 g of NIPAM monomer to the solution in step (3), and stir and polymerize at 60 °C for 3 h.

[0108] (5) After polymerization, vacuum filter to collect the reaction product, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0109] Second step, synthesize the hydrogel electrolyte:

[0110] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0111] ② Add 0.036 g of GO-g-PNIPAM to the solution in step ①.

[0112] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0113] Example 3

[0114] Step 1: Synthesize graphene oxide-grafted poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0115] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0116] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0117] (3) Dropwise add solution B to solution A and stir for 60 min to remove oxygen.

[0118] (4) Under a nitrogen atmosphere, add 1.13 g of NIPAM monomer to the solution obtained in step (3) and stir and polymerize at 60 °C for 3 h.

[0119] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0120] Step 2: Synthesize a hydrogel electrolyte:

[0121] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0122] ② Add 0.36 g of GO-g-PNIPAM to the solution obtained in step ①.

[0123] ③ Seal the beaker, stir the mixed solution obtained in step ② at 40 °C for 6 h, sonicate for 10 min, filter it into a film (1 mm) and then dry it in vacuo for 2 - 3 days to obtain a P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0124] Example 4

[0125] Step 1: Synthesize graphene oxide-grafted poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0126] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0127] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0128] (3) Dropwise add solution B to solution A and stir for 60 min to remove oxygen.

[0129] (4) Under a nitrogen atmosphere, 0.57 g of NIPAM monomer was added to the solution in step (3), and the mixture was stirred and polymerized at 60 °C for 3 h.

[0130] (5) After polymerization, the reaction product was collected by vacuum filtration, washed with alcohol and DMF to remove residual monomers and free polymers. The brown product was redispersed in DMF and stirred for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0131] The second step: synthesize the hydrogel electrolyte:

[0132] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0133] ② Add 0.036 g of GO-g-PNIPAM to the solution in step ①.

[0134] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0135] Example 5

[0136] The first step: synthesize graphene oxide grafted with poly-N-isopropylacrylamide (GO-g-PNIPAM):

[0137] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0138] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0139] (3) Slowly add solution B dropwise to solution A, stir for 60 min to remove oxygen.

[0140] (4) Under a nitrogen atmosphere, 0.57 g of NIPAM monomer was added to the solution in step (3), and the mixture was stirred and polymerized at 60 °C for 3 h.

[0141] (5) After polymerization, the reaction product was collected by vacuum filtration, washed with alcohol and DMF to remove residual monomers and free polymers. The brown product was redispersed in DMF and stirred for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0142] The second step: synthesize the hydrogel electrolyte:

[0143] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0144] ② Add 0.18 g of GO-g-PNIPAM to the solution in step ①.

[0145] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0146] Example 6

[0147] First step, synthesize graphene oxide grafted with poly-N-isopropylacrylamide (GO-g-PNIPAM):

[0148] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0149] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0150] (3) Dropwise add solution B to solution A, stir for 60 min to remove oxygen.

[0151] (4) Under a nitrogen atmosphere, add 0.57 g of NIPAM monomer to the solution in step (3), and stir and polymerize at 60 °C for 3 h.

[0152] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration 80 - 100 mg / mL).

[0153] Second step, synthesize the hydrogel electrolyte:

[0154] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0155] ② Add 0.36 g of GO-g-PNIPAM to the solution in step ①.

[0156] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0157] Example 7

[0158] Step 1, synthesize graphene oxide grafted with poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0159] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0160] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0161] (3) Dropwise add solution B to solution A and stir for 60 min to remove oxygen.

[0162] (4) Under a nitrogen atmosphere, add 2.26 g of NIPAM monomer to the solution in step (3) and stir and polymerize at 60 °C for 3 h.

[0163] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration: 80 - 100 mg / mL).

[0164] Step 2, synthesize a hydrogel electrolyte:

[0165] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0166] ② Add 0.036 g of GO-g-PNIPAM to the solution in step ①.

[0167] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, sonicate for 10 min, filter it into a film (1 mm) and then dry it in vacuum for 2 - 3 days to obtain a P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0168] Example 8

[0169] Step 1, synthesize graphene oxide grafted with poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0170] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0171] (2) Dissolve 0.2 g of ammonium cerium nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0172] (3) Add solution B dropwise to solution A and stir for 60 min to remove oxygen.

[0173] (4) Under a nitrogen atmosphere, add 2.26 g of NIPAM monomer to the solution from step (3) and stir and polymerize at 60 °C for 3 h.

[0174] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration 80 - 100 mg / mL).

[0175] Second step, synthesize the hydrogel electrolyte:

[0176] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0177] ② Add 0.18 g of GO-g-PNIPAM to the solution from step ①.

[0178] ③ Seal the beaker, stir the mixed solution from step ② at 40 °C for 6 h, sonicate for 10 min, filter it into a film (1 mm) and then dry it in vacuo for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0179] Example 9

[0180] First step, synthesize graphene oxide-grafted poly(N-isopropylacrylamide) (GO-g-PNIPAM):

[0181] (1) Ultrasonically disperse 50 mg of graphene oxide in 100 mL of deionized water to obtain solution A;

[0182] (2) Dissolve 0.2 g of ammonium cerium(IV) nitrate in 20 mL of 1 mol / L nitric acid solution to obtain solution B;

[0183] (3) Add solution B dropwise to solution A and stir for 60 min to remove oxygen.

[0184] (4) Under a nitrogen atmosphere, add 2.26 g of NIPAM monomer to the solution from step (3) and stir and polymerize at 60 °C for 3 h.

[0185] (5) After polymerization, collect the reaction product by vacuum filtration, wash it with alcohol and DMF to remove residual monomers and free polymers. Redisperse the brown product in DMF and stir for 12 h to finally obtain a black GO-g-PNIPAM suspension (concentration 80 - 100 mg / mL).

[0186] Step 2: Synthesize the hydrogel electrolyte:

[0187] ① Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF.

[0188] ② Add 0.36 g of GO-g-PNIPAM to the solution in step ①.

[0189] ③ Seal the beaker, stir the mixed solution in step ② at 40 °C for 6 h, ultrasonicate for 10 min, filter it into a film (1 mm), and then dry it in vacuum for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte.

[0190] Comparative Example 1

[0191] Synthesize the poly(N-isopropylacrylamide) hydrogel electrolyte:

[0192] (1) Dissolve 7.27 g of Zn(OTF)₂ and 1 g of NIPAM monomer in 10 mL of deionized water and stir at room temperature for 60 min.

[0193] (2) Add 2 mg of N,N'-methylenebisacrylamide and 15 mg of potassium persulfate to step (1) and continue stirring for 60 min.

[0194] (3) Add 20 μL of N,N,N',N'-tetramethylethylenediamine to step (2), stir for 20 min, remove oxygen, and purge with nitrogen.

[0195] (4) Inject the solution obtained in step (3) into a polytetrafluoroethylene mold and freeze it at 5 °C for 24 h to obtain the PNIPAM hydrogel electrolyte.

[0196] Comparative Example 2

[0197] Synthesize the graphene oxide / poly(N-isopropylacrylamide) hydrogel electrolyte:

[0198] (1) Ultrasonically disperse 10 mg of graphene oxide in 10 mL of deionized water, dissolve 7.27 g of Zn(OTF)₂ and 1 g of NIPAM monomer in the above solution, and stir at room temperature for 60 min.

[0199] (2) Add 2 mg of N,N'-methylenebisacrylamide and 15 mg of potassium persulfate to step (1) and continue stirring for 60 min.

[0200] (3) Add 20 μL of N,N,N',N'-tetramethylethylenediamine to step (2), stir for 20 min, remove oxygen, and purge with nitrogen.

[0201] (4) Inject the solution obtained in step (3) into a polytetrafluoroethylene mold and freeze it at 5 °C for 24 h to obtain the GO / PNIPAM hydrogel electrolyte.

[0202] Comparative Example 3

[0203] Synthesize the P(VDF-TrFE-CTFE) hydrogel electrolyte:

[0204] Dissolve 3.63 g of P(VDF-TrFE-CTFE) and 3.63 g of Zn(OTF)₂ in 5 mL of DMF and stir at 25 °C for 12 h. Then inject the obtained solution into a polytetrafluoroethylene mold and vacuum dry it at 60 °C for 2 - 3 days to obtain the P(VDF-TrFE-CTFE) hydrogel electrolyte.

[0205] Effect Example

[0206] (a) Conduct mechanical property tests on the flexible, conductive, and high-temperature-resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel prepared in Example 1 at different temperatures (placed at 25 °C, 55 °C, and 85 °C for 12 h) (set different temperatures in a high and low temperature chamber and place for 12 h, then take out and conduct tensile tests at 25 °C. Clamp both ends of the hydrogel with tweezers, measure the stretched length, and set three repetitions).

[0207] The results are as Figure 2 shown: It can be seen that even when placed at 55 °C and 85 °C for 12 h, the hydrogel still has good flexibility.

[0208] (b) Measure the ionic conductivity of the flexible, conductive, and high-temperature-resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel prepared in Example 1 (on an electrochemical workstation, with a frequency range of 0.01 Hz - 100 kHz, measure the impedance of the battery, and calculate the ionic conductivity according to the impedance of the battery, σ = L / RS, where σ represents the ionic conductivity (S / cm), L is the thickness of the hydrogel (cm), R is the measured impedance of the battery (Ω), and S is the area (cm 2 )); set three repetitions).

[0209] The results are as Figure 3 shown: It can be seen that as the temperature increases, the ionic conductivity increases.

[0210] (c) Using MXene / VO2 as the positive electrode and zinc sheet as the negative electrode, and the flexible conductive high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogels prepared in Examples 1-9 and Comparative Examples 1-3 as the electrolyte and separator, flexible zinc-ion batteries were assembled respectively. The flexible zinc-ion batteries were tested for constant current charge and discharge (current of 1 A) using a battery newwei tester, and three repetitions were set.

[0211] The results are as Figure 4 shown: It can be seen from the figure that the composite hydrogel synthesized in Example 1 of the present invention is the best solution, which can stably cycle 1000 times at a current of 1 A, and the capacity retention rate is 95% (capacity retention rate = specific capacity at the last cycle / specific capacity at the first cycle * 100%); among them, the specific capacity at the last cycle is 268.8 mAh / g, and the specific capacity at the first cycle is 283 mAh / g.

[0212] (d) The flexible conductive high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel prepared in Example 1 was applied to a flexible battery system, and the voltage before and after bending was measured (using a zinc sheet as the negative electrode, MXene / VO2 as the positive electrode, and P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel as the separator and electrolyte, which were encapsulated in an aluminum-plastic film, and titanium foils were connected to the positive and negative electrodes respectively to lead out two pole ears to form a flexible zinc-ion battery. The voltage of the flexible zinc-ion battery before and after bending was measured with a multimeter), and three repetitions were set.

[0213] The results are as Figure 5 shown: When this hydrogel is applied to a flexible battery system, it has a stable voltage before and after bending.

[0214] (e) The flexible conductive high-temperature resistant P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel prepared in Example 1 was applied to a flexible battery system (using a zinc sheet as the negative electrode, MXene / VO2 as the positive electrode, and P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel as the separator and electrolyte, which were encapsulated in an aluminum-plastic film, and titanium foils were connected to the positive and negative electrodes respectively to lead out two pole ears to form a flexible zinc-ion battery. After three zinc-ion batteries were connected in series with wires, they were used to power an electronic watch, and three repetitions were set).

[0215] The results are as Figure 6 shown: When this hydrogel is applied to a flexible battery system, it can stably power an electronic watch.

[0216] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a flexible conductive high-temperature resistant hydrogel, characterized in that, It includes the following steps: (1) Synthesize poly(N-isopropylacrylamide) grafted graphene: Ultrasonically disperse graphene oxide in water to obtain mixture A; dissolve ammonium cerium nitrate in nitric acid solution to obtain mixture B; then add mixture B dropwise to mixture A and stir evenly to obtain mixture C; further, under the atmosphere of protective gas and at 60±5°C, add NIPAM monomer to mixture C for polymerization reaction. After the reaction ends, filter and collect the reaction product, and wash it to obtain GO-g-PNIPAM; (2) Synthesize hydrogel electrolyte Stir and disperse GO-g-PNIPAM in N,N-dimethylformamide to obtain a GO-g-PNIPAM suspension; dissolve P(VDF-TrFE-CTFE) and Zn(OTF)₂ in N,N-dimethylformamide to obtain mixture D; then add mixture D to the GO-g-PNIPAM suspension, stir and react at 40±5°C under sealed conditions, and then perform ultrasonic treatment, filtration to form a film, and vacuum drying to obtain the P(VDF-TrFE-CTFE) / GO-g-PNIPAM hydrogel electrolyte, that is, the flexible conductive high-temperature resistant hydrogel.

2. The preparation method of the flexible conductive high-temperature resistant hydrogel according to claim 1, wherein: The mass ratio of the graphene oxide to ammonium cerium nitrate in step (1) is 1:1 to 10; The dosage of the NIPAM monomer in step (1) is calculated according to 0.1 mmol to 0.4 mmol of NIPAM monomer per milligram of graphene oxide; The mass ratio of P(VDF-TrFE-CTFE) to Zn(OTF)₂ in step (2) is 1 to 10:1; The weight ratio of P(VDF-TrFE-CTFE) to GO-g-PNIPAM in step (2) is 1:0.01 to 0.

1.

3. The preparation method of the flexible conductive high-temperature resistant hydrogel according to claim 2, wherein: The mass ratio of the graphene oxide to ammonium cerium nitrate in step (1) is 1:4; The mass ratio of P(VDF-TrFE-CTFE) to Zn(OTF)₂ in step (2) is 1:

1.

4. The preparation method of the flexible conductive high-temperature resistant hydrogel according to claim 1, wherein: The dosage of water in step (1) is calculated according to 1 to 5 mL of water per milligram of graphene oxide; The concentration of the nitric acid solution in step (1) is 0.5 to 3 mol / L; The dosage of the nitric acid solution in step (1) is calculated according to 50 to 200 mL of nitric acid solution per gram of ammonium cerium nitrate; The concentration of the GO-g-PNIPAM suspension in step (2) is 80 to 100 mg / mL; The dosage of N,N-dimethylformamide in step (2) is calculated according to 1 to 5 mL of N,N-dimethylformamide per gram of P(VDF-TrFE-CTFE).

5. The preparation method of the flexible conductive high-temperature resistant hydrogel according to claim 4, wherein: The amount of water described in step (1) is calculated as 2 mL of water per milligram of graphene oxide; The concentration of the nitric acid solution described in step (1) is 1 mol / L; The amount of the nitric acid solution described in step (1) is calculated as 100 mL of nitric acid solution per gram of ammonium cerium nitrate; The amount of N,N-dimethylformamide described in step (2) is calculated as 1 - 2 mL of N,N-dimethylformamide per gram of P(VDF-TrFE-CTFE); 6. The preparation method of the flexible conductive high-temperature resistant hydrogel according to claim 1, characterized in that: The stirring time described in step (1) is 30 - 180 min; The protective gas described in step (1) is nitrogen; The polymerization reaction time described in step (1) is 1 - 6 h; The cleaning described in step (1) is carried out using alcohol and N,N-dimethylformamide; The stirring and dispersing time described in step (2) is 2 - 36 h; The ultrasonic treatment time described in step (2) is 5 - 60 min; The vacuum drying time described in step (2) is 2 - 3 days.

7. A flexible conductive high-temperature resistant hydrogel, characterized in that: Prepared by the method according to any one of claims 1 - 6.

8. Application of the flexible conductive high-temperature resistant hydrogel according to claim 7 in the preparation of flexible zinc ion batteries.

9. A flexible zinc-ion battery, characterized in that: Using MXene / VO2 as the positive electrode, a zinc sheet as the negative electrode, and the flexible conductive high-temperature resistant hydrogel according to claim 7 as the electrolyte and separator.

10. The flexible zinc ion battery according to claim 9, characterized in that: The MXene / VO2 is prepared by the following method: adding VO2 and MXene into water for ultrasonic treatment, suction filtration, and vacuum drying to obtain MXene / VO2; The mass ratio of the VO2 and MXene is 1:1 - 3; The ultrasonic treatment time is 30 - 60 min.

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