Self-supporting flexible silver-rich electrode and preparation method and application thereof

Abstract

The invention discloses a self-supporting flexible silver-rich electrode as well as a preparation method and application thereof. The self-supporting flexible silver-rich electrode comprises an MXene sheet layer, aramid nanofibers and silver nanoparticles. The preparation method of the self-supporting flexible silver-rich electrode comprises five preparation steps. According to the flexible energy storage battery, a self-supporting flexible silver-rich electrode is adopted as a positive electrode, a negative electrode is metal zinc or an alloy sheet thereof, and an electrolyte is neutral hydrogel or an ionic liquid base. The method has the advantages that in-situ reduction deposition of the MXene on the silver ions is adopted, on one hand, functional groups and interlayer spaces on the surfaces of MXene sheet layers provide good sites for deposition of the silver ions; and on the other hand, Ag < + > is directly reduced into AgNPs on the surface of MXene by utilizing the reducibility of MXene, so that uniform dispersion and strong combination of silver nanoparticles in the electrode are realized. The ANF serves as a nano reinforced fiber to form a hydrogen bond cross-linked network between MXene sheet layers, so that the tensile strength and the bending resistance of the composite film are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of silver-rich electrodes, and more particularly to a self-supporting flexible silver-rich electrode, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of emerging fields such as wearable electronic devices, flexible displays, and smart textiles, the demand for energy storage devices with mechanical flexibility characteristics such as being thin, light, and bendable is increasing day by day. Therefore, the development of flexible batteries with excellent electrochemical performance and mechanical flexibility has become a research hotspot.

[0003] Chinese Patent Application CN119608161A discloses a preparation method of a carbon fiber cloth@Si x Fe 1-x O2 nanorod material. Using carbon fiber cloth as a carrier, Si x Fe 1-x O2 nanorods are in-situ grown on its surface through a combination of solution reaction and heat treatment, and the obtained electrode is used as the negative electrode material of a flexible battery. Chinese Patent Application CN118281371A discloses a preparation method of a leather-integrated all-flexible zinc ion battery. Using leather as a substrate, a conductive polymer and zinc powder are respectively compounded on both sides of the leather, and different current lead-out materials and flexible outer packages are selected to make a flexible zinc ion battery.

[0004] Although the above related technologies can achieve the flexibility of the battery, under mechanical stress, the electrode layer is prone to peeling or cracking, seriously affecting the cycle stability and service life of the device. In order to address the bending problem of the electrode or battery, it is necessary to prepare the flexible electrode into a single-structured electrode, which can not only achieve the flexibility of the battery but also improve the bending service life of the battery. Summary of the Invention

[0005] The first object of the present invention is to provide a self-supporting flexible silver-rich electrode.

[0006] The second object of the present invention is to provide a preparation method of a self-supporting flexible silver-rich electrode.

[0007] The third object of the present invention is to provide a flexible energy storage battery.

[0008] The first object of the present invention is implemented by the following technical solution: A self-supporting flexible silver-rich electrode, which includes MXene sheets, aramid nanofibers, and silver nanoparticles. The MXene sheets and the aramid nanofibers are intertwined to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed in the MXene / ANF framework; the mass ratio of MXene sheets, aramid nanofibers, and silver nanoparticles is 100:2 - 20:25 - 100.

[0009] Furthermore, the size of the MXene sheets is 1 - 2 μm.

[0010] Furthermore, the diameter of the aramid nanofibers is 10 - 50 nm and the length is 1 - 150 μm.

[0011] Furthermore, the silver nanoparticles are zero-valent silver particles in-situ generated within the MXene / ANF framework, with a particle size of 5 - 50 nm.

[0012] The second object of the present invention is implemented by the following technical solution: A method for preparing a self-supporting flexible silver-rich electrode, comprising the following steps: S1: Prepare an MXene dispersion containing MXene sheets; S2: Prepare an ANF dispersion containing aramid nanofibers; S3: Mix the ANF dispersion obtained in S2 with a silver ion solution to obtain a precursor dispersion; S4: Slowly drop the MXene dispersion prepared in S1 into the precursor dispersion to obtain an MXene@ANF@AgNPs composite dispersion; S5: Subject the MXene@ANF@AgNPs composite dispersion obtained in S4 to vacuum filtration and rinsing in sequence, and then perform drying and heat treatment successively to obtain a self-supporting flexible silver-rich electrode; The drying temperature in S5 is 25 - 80 °C, the time is 1 - 2 h, and the heat treatment is vacuum annealing at 300 - 450 °C for 1 h.

[0013] Furthermore, the said S1 includes the following steps: S1-1: Treat 400-mesh MAX-phase ceramic in an HF solution at 30 - 45 °C using a chemical etching method to obtain MXene sheets; S1-2: Disperse the MXene sheets obtained in S1-1 in water, perform ultrasonic exfoliation and centrifugation, and take the supernatant to obtain an MXene dispersion.

[0014] Furthermore, the specific treatment process of the said S2 is as follows: S2-1: Add aramid nanofibers to an organic solvent and magnetically stir at 40 °C for 2 - 24 h to obtain an ANF / DMSO dispersion; S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath for quenching and precipitation, and then perform washing and ultrasonic dispersion to obtain an ANF dispersion; Among them, the precursor of the aramid nanofibers is 6-mm-long aramid short fibers, the organic solvent is a potassium hydroxide-containing dimethyl sulfoxide solution, and the mass ratio of potassium hydroxide to the dimethyl sulfoxide solution is 1 - 3:550.

[0015] Furthermore, the specific process of S3 is as follows: The ANF dispersion obtained in S2 is mixed with a silver ion solution and stirred at room temperature to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, silver acetate solution, or silver molybdate solution with a silver ion concentration of 0.01 - 0.06 mol / l.

[0016] Furthermore, the specific process of S4 is: The precursor dispersion obtained in S3 is subjected to magnetic stirring or ultrasonic dispersion, and the MXene dispersion prepared in S1 is added dropwise at a rate of 1 - 10 ml per minute, and the reaction is carried out at a temperature of 25 - 80 °C for 0.5 h to obtain a MXene@ANF@AgNPs composite dispersion.

[0017] The third object of the present invention is implemented by the following technical solution: A flexible energy storage battery, characterized in that it uses a self - supporting flexible silver - rich electrode as the positive electrode, a metal zinc or its alloy thin sheet as the negative electrode, and a hydrogel electrolyte as the electrolyte.

[0018] Advantages of the present invention: (1) The in - situ reduction and deposition of silver ions by MXene. On the one hand, the functional groups and interlayer space on the surface of MXene sheets provide good sites for the deposition of silver ions; on the other hand, the reducibility of MXene enables Ag + to be directly reduced to AgNPs on the surface of MXene, thus realizing the uniform dispersion and strong binding of silver nanoparticles in the electrode. (2) Introducing a small amount of ANF to construct a composite film with MXene. ANF forms a hydrogen - bond cross - linked network between MXene sheets as a nano - reinforcing fiber, significantly improving the tensile strength and anti - bending performance of the composite film. This binder - free design avoids the problems of decreased conductivity and volume expansion that may be brought by traditional polymer binders, and endows the electrode with a higher content of conductive components and better flexibility. (3) Through appropriate drying or heat treatment methods, post - treatment of the prepared composite electrode can further improve the interfacial bonding and conductive contact between MXene sheets, AgNPs, and ANF, ensuring that the electrode remains stable under repeated mechanical deformation and long - term electrochemical cycling, and can ensure the conductivity and electrochemical stability of the electrode. (4) In the present invention, through "Ag +First, it combines with ANF to form a precursor, and then MXene is introduced for mild reduction to generate AgNPs. In this preparation sequence, the obtained silver particles are evenly distributed in the ANF network and interact nestedly with ANF during the formation process. The embedding positions of AgNPs are at the key nodes between the fibers and the lamellae, playing a dual role of connecting the network path and enhancing the structural stability. At the same time, MXene and ANF interact through hydrogen bonds to jointly construct a stable three-dimensional network structure. Through the mild reduction of MXene, AgNPs are in-situ induced to deposit at the interface between ANF and MXene, which can not only precisely control the growth position and distribution state of silver particles, but also achieve the synergistic connection between the lamellae and the fibers without destroying the structure of MXene. This preparation method effectively avoids problems such as particle agglomeration, insufficient adhesion, or uneven conductivity, endows the film with excellent conductivity, flexibility, and electrochemical stability, and constructs a flexible composite conductive film with both structural integrity and performance synergy.

[0019] The electrode material of the present invention overcomes many defects of traditional silver-rich electrodes in the prior art. Through the synergistic construction of MXene / ANF and the in-situ introduction of silver nanoparticles, the prepared self-supporting flexible silver-rich electrode not only greatly increases the silver content but also maintains excellent mechanical flexibility and structural stability. Moreover, this electrode exhibits high specific capacity and long cycle life in flexible silver-zinc batteries and can still stably charge and discharge under repeated bending conditions. Therefore, the technical solution provided by the present invention is a high-performance and multifunctional flexible electrode material, providing a new solution for flexible energy storage devices and related fields. Brief Description of the Drawings

[0020] Figure 1 SEM image of the self-supporting flexible silver-rich electrode in Example 1.

[0021] Figure 2 Partial enlarged schematic diagram of the distribution of AgNPs in Example 1.

[0022] Figure 3 Resistance diagram of Example 1 after 10,000 bending experiments.

[0023] Figure 4 Discharge capacity diagram of Example 1 after 10,000 bending experiments.

[0024] Figure 5 Discharge capacity diagram of the flexible energy storage battery in Example 7 after 6,000 bending experiments. Detailed Description of the Invention

[0025] Example 1: A self-supporting flexible silver-rich electrode, which includes MXene sheets, aramid nanofibers, and silver nanoparticles. The MXene sheets and aramid nanofibers are intertwined to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed in the MXene / ANF framework. The mass ratio of MXene sheets, aramid nanofibers, and silver nanoparticles is 100:7.5:79. The size of the MXene sheets is 1-2 μm; the diameter of the aramid nanofibers is 10-50 nm, and the length is 1-150 μm. The silver nanoparticles are zero-valent silver particles in-situ generated within the MXene / ANF framework, with a particle size of 5-50 nm.

[0026] After cutting the self-supporting flexible silver-rich electrode of this example into several basic squares, different experiments and studies were carried out, and the specific results are as follows: Take one basic square and observe it under a scanning electron microscope. Its structure is as Figure 1 shown. It can be seen from Figure 1 that the self-supporting flexible silver-rich electrode prepared in this example has a layered structure. Figure 2 Figure [Figure number not provided in the original] is a partially enlarged schematic diagram of the AgNPs distribution in the self-supporting flexible silver-rich electrode generated by ChemDraw, showing that silver nanoparticles are deposited on the MXene sheets, forming a conductive lattice with uniform particle size and dense distribution. The AgNPs are tightly combined with the MXene, realizing an excellent electron transport path; the figure also shows that the ANF penetrates between the MXene sheets, providing mechanical support and connecting the components through surface hydrogen bonds.

[0027] The sheet resistance of the basic square of this example is 0.45 Ω / sq. Take one basic square and conduct a 180° bending experiment 10,000 times through a bending test machine. The conductivity comparison chart before and after bending is as Figure 3 shown. After 10,000 times of bending, the resistance loss of the basic square only increases by 0.04 Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this example has strong anti-bending ability and good mechanical durability. The discharge capacity chart before and after bending is as Figure 4 shown. At a current density of 0.8 mA cm -2 , its discharge capacity retention rate is 90.9%, showing good capacitance stability.

[0028] The sheet resistance of the electrode film in this example is reduced to 0.45 Ω / sq, and the flexibility retention and mechanical stability are greatly improved. At the same time, the film shows excellent capacity retention rate after bending test.

[0029] Example 2: A self-supporting flexible silver-rich electrode, which comprises MXene sheets, aramid nanofibers and silver nanoparticles. The MXene sheets and aramid nanofibers are intertwined to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed in the MXene / ANF framework. The mass ratio of the MXene sheets, aramid nanofibers and silver nanoparticles is 100:2:25. The size of the MXene sheets is 1-2 μm; the diameter of the aramid nanofibers is 10-50 nm, and the length is 1-150 μm. The silver nanoparticles are zero-valent silver particles in-situ generated in the MXene / ANF framework, and the particle size is 5-50 nm.

[0030] The base sheet resistance of this example is 0.45 Ω / sq. Take a base sheet and conduct 10,000 times of 180° bending experiments through a bending testing machine. The conductivity after bending is 0.46 Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this example has strong anti-bending ability and good mechanical durability. At a current density of 0.8 mA cm -2 The discharge capacity retention rate after bending is 95%, showing good capacitance stability.

[0031] Example 3: A self-supporting flexible silver-rich electrode, which comprises MXene sheets, aramid nanofibers and silver nanoparticles. The MXene sheets and aramid nanofibers are intertwined to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed in the MXene / ANF framework. The mass ratio of the MXene sheets, aramid nanofibers and silver nanoparticles is 100:20:100. The size of the MXene sheets is 1-2 μm; the diameter of the aramid nanofibers is 10-50 nm, and the length is 1-150 μm. The silver nanoparticles are zero-valent silver particles in-situ generated in the MXene / ANF framework, and the particle size is 5-50 nm.

[0032] The base sheet resistance of this example is 1.5 Ω / sq. Take a base sheet and conduct 10,000 times of 180° bending experiments through a bending testing machine. The conductivity after bending is 1.6 Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this example has strong anti-bending ability and good mechanical durability. At a current density of 0.8 mA cm -2 The discharge capacity retention rate after bending is 85%, showing good capacitance stability.

[0033] Example 4: The preparation method of the self-supporting flexible silver-rich electrode described in Example 1, comprising the following steps: S1: Prepare a MXene dispersion containing MXene sheets S1-1: Treat 400-mesh MAX-phase ceramic in an HF solution at 35 °C by chemical etching method to obtain MXene sheets; S1-2: Disperse the MXene flakes obtained in S1-1 in water, perform ultrasonic exfoliation and centrifugation, and take the supernatant to obtain the MXene dispersion.

[0034] S2: Prepare an ANF dispersion containing aramid nanofibers; S2-1: Add aramid nanofibers to an organic solvent, and magnetically stir at 40 °C for 4 h to obtain an ANF / DMSO dispersion; S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath for quenching and precipitation, then wash and ultrasonically disperse to obtain the ANF dispersion; Among them, the precursor of the aramid nanofibers is aramid short fibers with a length of 6 mm, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to the dimethyl sulfoxide solution is 1.5:550.

[0035] S3: Mix the ANF dispersion obtained in S2 with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: After mixing the ANF dispersion obtained in S2 with the silver ion solution, stir at room temperature to allow the surface functional groups of the aramid nanofibers to complex with the silver ions to obtain the precursor dispersion; the silver ion solution is a silver nitrate solution, silver acetate solution or silver molybdate solution with a silver ion concentration of 0.03 mol / l.

[0036] S4: Slowly add the MXene dispersion prepared in S1 dropwise to the precursor dispersion to obtain the MXene@ANF@AgNPs composite dispersion; the specific process is: Magnetically stir the precursor dispersion obtained in S3, and add the MXene dispersion prepared in S1 dropwise at a rate of 5 ml per minute, and react at a temperature of 50 °C for 0.2 h to obtain the MXene@ANF@AgNPs composite dispersion.

[0037] S5: Subject the MXene@ANF@AgNPs composite dispersion obtained in S4 to vacuum filtration and rinsing in sequence, and then perform drying and heat treatment successively. Among them, drying is carried out at 45 °C for 1.5 h, and heat treatment is vacuum annealing at 400 °C for 1 h; a self-supporting flexible silver-rich electrode is obtained.

[0038] Example 5: The preparation method of the self-supporting flexible silver-rich electrode described in Example 2 includes the following steps: S1: Prepare an MXene dispersion containing MXene flakes S1-1: Treat 400-mesh MAX phase ceramic in an HF solution at 30 °C using a chemical etching method to obtain MXene flakes; S1-2: Disperse the MXene flakes obtained in S1-1 in water, perform ultrasonic exfoliation and centrifugation, and take the supernatant to obtain the MXene dispersion.

[0039] S2: Prepare an ANF dispersion containing aramid nanofibers; S2-1: Add aramid nanofibers to an organic solvent and stir magnetically at 40 °C for 2 h to obtain an ANF / DMSO dispersion; S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath for quenching and precipitation, then wash and ultrasonically disperse it to obtain an ANF dispersion; Among them, the precursor of the aramid nanofibers is aramid short fibers with a length of 6 mm, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to the dimethyl sulfoxide solution is 1:550.

[0040] S3: Mix the ANF dispersion obtained in S2 with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: After mixing the ANF dispersion obtained in S2 with the silver ion solution, stir at room temperature to allow the surface functional groups of the aramid nanofibers to complex with the silver ions to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, silver acetate solution or silver molybdate solution with a silver ion concentration of 0.01 mol / l.

[0041] S4: Slowly drop the MXene dispersion prepared in S1 into the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; the specific process is: Ultrasonically disperse the precursor dispersion obtained in S3, and drop the MXene dispersion prepared in S1 at a rate of 1 ml per minute, and react at a temperature of 25 °C for 0.5 h to obtain a MXene@ANF@AgNPs composite dispersion.

[0042] S5: Subject the MXene@ANF@AgNPs composite dispersion obtained in S4 to vacuum filtration and rinsing in sequence, and then perform drying and heat treatment successively. Among them, drying is carried out at 25 °C for 2 h, and heat treatment is carried out at 300 °C for vacuum annealing for 1 h; a self-supporting flexible silver-rich electrode is obtained.

[0043] Example 6: The preparation method of the self-supporting flexible silver-rich electrode described in Example 3 includes the following steps: S1: Prepare a MXene dispersion containing MXene sheets S1-1: Treat a 400-mesh MAX phase ceramic in an HF solution at 45 °C using a chemical etching method to obtain MXene sheets; S1-2: Disperse the MXene sheets obtained in S1-1 in water, perform ultrasonic exfoliation and centrifugation, and take the supernatant to obtain a MXene dispersion.

[0044] S2: Prepare an ANF dispersion containing aramid nanofibers; S2-1: Add aramid nanofibers to an organic solvent and stir magnetically at 40 °C for 24 h to obtain an ANF / DMSO dispersion; S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath for quenching and precipitation, then wash and ultrasonically disperse it to obtain an ANF dispersion; Among them, the precursor of the aramid nanofibers is aramid staple fibers 6 mm long, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to the dimethyl sulfoxide solution is 3:550.

[0045] S3: Mix the ANF dispersion obtained in S2 with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: After mixing the ANF dispersion obtained in S2 with the silver ion solution, stir at room temperature to allow the surface functional groups of the aramid nanofibers to complex with the silver ions to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, silver acetate solution or silver molybdate solution with a concentration of 0.06 mol / l.

[0046] S4: Slowly drop the MXene dispersion prepared in S1 into the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; the specific process is: Magnetically stir the precursor dispersion obtained in S3, and drop the MXene dispersion prepared in S1 at a rate of 10 ml per minute, and react at a temperature of 80 °C for 0.5 h to obtain a MXene@ANF@AgNPs composite dispersion.

[0047] S5: Subject the MXene@ANF@AgNPs composite dispersion obtained in S4 to vacuum filtration and rinsing treatments in sequence, and then perform drying and heat treatment successively. Among them, drying is carried out at 85 °C for 1 h, and heat treatment is vacuum annealing at 460 °C for 1 h; a self-supporting flexible silver-rich electrode is obtained.

[0048] The preparation method of the present invention first introduces Ag + into the ANF dispersion to construct a precursor system. During the subsequent addition of MXene, the reducibility of MXene is utilized to make Ag +In-situ generation of Ag nanoparticles. The obtained silver particles are uniformly distributed in the ANF network and interact synergistically with ANF during the formation process. The embedding position of AgNPs is at the key nodes between the fibers and the lamellae, playing a dual role of connecting the network path and enhancing the structural stability. Meanwhile, MXene and ANF interact through hydrogen bonds to jointly construct a stable three-dimensional network structure. By the mild reduction of MXene, AgNPs are in-situ induced to deposit at the interface between ANF and MXene, which can not only accurately control the growth position and distribution state of silver particles, but also achieve the synergistic connection between the lamellae and the fibers without damaging the structure of MXene. This preparation method effectively avoids problems such as particle agglomeration, insufficient adhesion, or uneven conductivity, endowing the film with excellent conductivity, flexibility, and electrochemical stability, and constructing a flexible composite conductive film with both structural integrity and performance synergy.

[0049] This three-phase synergistic mechanism enables AgNPs to not only exist as a conductive enhancement component, but also become a conductive node connecting ANF fibers and MXene sheets, thus significantly enhancing the conductive path, flexibility, and interfacial adhesion of the membrane structure.

[0050] Example 7: A flexible energy storage battery uses the self-supporting flexible silver-rich electrode described in Example 1 as the positive electrode, a metal zinc as the negative electrode, and a hydrogel electrolyte as the electrolyte. The flexible energy storage battery prepared in this example, after 6000 times of 180° bending tests at a current density of 0.8 mA cm -2 , the discharge capacity comparison chart is as Figure 5 shown. After the bending test, its discharge capacity retention rate is 91.8%, indicating its good electrochemical stability.

[0051] In some embodiments, the negative electrode of the flexible energy storage battery can also be a thin alloy sheet of metal zinc.

[0052] Generally speaking, aiming at the goal of synergistically improving the conductivity, flexibility, and electrochemical stability of the flexible conductive electrode, the present invention proposes a "MXene@ANF@AgNPs" composite system with a clear construction sequence and structure control strategy. Compared with the prior art, its significant progress is reflected in the following aspects: First, in terms of the construction idea, the present invention adopts a sequential regulation strategy of "Ag + first combines with ANF to form a precursor, and then MXene is introduced for mild reduction to generate AgNPs", avoiding the problem of structural damage caused by the direct reaction between Ag + and MXene, and ensuring good interfacial stability and synergistic binding mechanism among the three components.

[0053] Secondly, in terms of structural features, AgNPs are in-situ induced to deposit between ANF fibers and MXene sheets, forming a three-dimensional nested conductive network of "particle connection nodes - fiber support frameworks - sheet conductive channels". This network not only improves the electron transport efficiency but also enhances the mechanical integrity and durable deformation ability of the flexible film.

[0054] Thirdly, in terms of preparation control, the present invention realizes precise regulation of the distribution position, particle size, and embedding depth of silver particles, avoiding structural stability defects such as AgNPs agglomeration, sheet delamination, or interfacial delamination in the comparative technology, thereby obtaining an integrated electrode material with balanced performance.

[0055] Finally, in terms of actual performance, the flexible electrode film prepared by the present invention exhibits an extremely low surface resistance, excellent flexible deformation retention, and a capacity retention rate as high as 90.9% after bending.

[0056] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A self-supporting flexible silver-rich electrode, characterized in that, It includes MXene sheets, aramid nanofibers and silver nanoparticles. The MXene sheets and the aramid nanofibers are intertwined to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed in the MXene / ANF framework; the mass ratio of the MXene sheets, the aramid nanofibers, and the silver nanoparticles is 100:2 - 20:25 - 100.

2. The self-supporting flexible silver-rich electrode according to claim 1, wherein The size of the MXene sheets is 1 - 2 μm.

3. The self-supporting flexible silver-rich electrode according to claim 1, wherein The diameter of the aramid nanofibers is 10 - 50 nm, and the length is 1 - 150 μm.

4. The self-supporting flexible silver-rich electrode according to claim 1, wherein The silver nanoparticles are zero-valent silver particles in-situ generated within the MXene / ANF framework, with a particle size of 5 - 50 nm.

5. A method for preparing a self-supporting flexible silver-rich electrode according to any one of claims 1 to 4, characterized in that, It includes the following steps: S1: Prepare a MXene dispersion containing MXene sheets; S2: Prepare an ANF dispersion containing aramid nanofibers; S3: Mix the ANF dispersion obtained in S2 with a silver ion solution to obtain a precursor dispersion; S4: Slowly drop the MXene dispersion prepared in S1 into the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; S5: Subject the MXene@ANF@AgNPs composite dispersion obtained in S4 to vacuum filtration and rinsing in sequence, and then perform drying and heat treatment successively to obtain a self-supporting flexible silver-rich electrode; In S5, the drying temperature is 25 - 80 °C, the time is 1 - 2 h, and the heat treatment is vacuum annealing at 300 - 450 °C for 1 h.

6. The preparation method of a self-supporting flexible silver-rich electrode according to claim 5, wherein, The said S1 includes the following steps: S1-1: Treat 400-mesh MAX-phase ceramic in an HF solution at 30 - 45 °C using a chemical etching method to obtain MXene sheets; S1-2: Disperse the MXene sheets obtained in S1-1 in water, perform ultrasonic exfoliation and centrifugation, and take the supernatant to obtain a MXene dispersion.

7. The preparation method of a self-supporting flexible silver-rich electrode according to claim 5, wherein The specific treatment process of the said S2 is as follows: S2-1: Add aramid nanofibers to an organic solvent, and perform magnetic stirring at 40 °C for 2 - 24 h to obtain an ANF / DMSO dispersion; S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath for quenching and precipitation, and then perform washing and ultrasonic dispersion to obtain an ANF dispersion; Among them, the precursor of the aramid nanofibers is 6-mm-long aramid short fibers, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to the dimethyl sulfoxide solution is 1 - 3:

550.

8. The preparation method of a self-supporting flexible silver-rich electrode according to claim 5, characterized in that, The specific process of the said S3 is as follows: Mix the ANF dispersion obtained in S2 with a silver ion solution and stir at room temperature to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, silver acetate solution or silver molybdate solution with a silver ion concentration of 0.01 - 0.06 mol / l.

9. The preparation method of a self-supporting flexible silver-rich electrode according to claim 5, characterized in that, The specific process of the said S4 is: Magnetically stir or ultrasonically disperse the precursor dispersion obtained in S3, and drop the MXene dispersion prepared in S1 at a speed of 1 - 10 ml per minute, and react at a temperature of 25 - 80 °C for 0.5 h to obtain a MXene@ANF@AgNPs composite dispersion.

10. A flexible energy storage battery, characterized in that, Using the self-supporting flexible silver-rich electrode described in any one of claims 1 to 4 as the positive electrode, the negative electrode is a metal zinc or its alloy sheet, and the electrolyte is a hydrogel electrolyte.

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