A self-supporting flexible silver-rich electrode and its preparation method and application

Abstract

The present invention discloses a self-supporting flexible silver-rich electrode and its preparation method and application. A self-supporting flexible silver-rich electrode includes MXene sheets, aramid nanofibers and silver nanoparticles. A preparation method of a self-supporting flexible silver-rich electrode includes 5 preparation steps. A flexible energy storage battery uses a self-supporting flexible silver-rich electrode as a positive electrode, a metal zinc or its alloy sheet as a negative electrode, and a neutral hydrogel or ionic liquid-based electrolyte. Advantages: MXene is used for in-situ reduction deposition of silver ions. On the one hand, the functional groups and interlayer spaces on the surface of the MXene sheet provide good sites for the deposition of silver ions; on the other hand, the reducing property of MXene is used to make Ag + Direct reduction to AgNPs on the MXene surface enables uniform dispersion and strong bonding of silver nanoparticles in the electrode. ANF, as a nano-reinforced fiber, forms a hydrogen-bonded cross-linked network between MXene sheets, significantly improving the tensile strength and flexural properties of the composite film.

Description

Technical Field

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

[0002] With the rapid development of emerging fields such as wearable electronic devices, flexible displays, and smart textiles, there is an increasing demand for energy storage devices that are both thin, lightweight, and bendable, among other mechanically flexible features. 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 carbon fiber cloth @Si x Fe 1-x The preparation method of O2 nanorod material is to use carbon fiber cloth as a carrier and in situ grow Si on its surface by combining solution reaction with heat treatment. x Fe 1-x O2 nanorods, the resulting electrode, are used as the negative electrode material for flexible batteries. Chinese patent application CN118281371A discloses a method for preparing a leather-based, fully flexible zinc-ion battery. Using leather as a substrate, conductive polymers and zinc powder are composited on both sides of the leather. The flexible zinc-ion battery is then fabricated using different current-conducting materials and flexible packaging.

[0004] While these technologies can achieve battery flexibility, the electrode layer is susceptible to peeling or cracking under mechanical stress, severely impacting the device's cycle stability and service life. To address the issue of electrode or battery bending, it is necessary to fabricate flexible electrodes into a single-structure electrode, which both achieves battery flexibility and extends the battery's bending life. 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 method for preparing 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, wherein the MXene sheets and the aramid nanofibers are interwoven to form a MXene / ANF skeleton, and the silver nanoparticles are uniformly distributed in the MXene / ANF skeleton; the mass ratio of the MXene sheets, aramid nanofibers and silver nanoparticles is 100:2-20:25-100.

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

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

[0011] Furthermore, the silver nanoparticles are zero-valent silver particles generated in situ within the MXene / ANF framework, and have 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:

[0013] S1: Preparation of MXene dispersion containing MXene sheets;

[0014] S2: preparing ANF dispersion containing aramid nanofibers;

[0015] S3: mixing the ANF dispersion obtained in S2 with the silver ion solution to obtain a precursor dispersion;

[0016] S4: Slowly add the MXene dispersion prepared in S1 to the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion;

[0017] S5: The MXene@ANF@AgNPs composite dispersion obtained in S4 is subjected to vacuum filtration, rinsing, drying and heat treatment to obtain a self-supporting flexible silver-rich electrode;

[0018] The drying temperature in S5 is 25-80° C. and the drying time is 1-2 hours, and the heat treatment is vacuum annealing at 300-450° C. for 1 hour.

[0019] Furthermore, the S1 includes the following steps:

[0020] S1-1: Chemical etching was performed on 400-mesh MAX phase ceramics in a 30-45°C HF solution to obtain MXene sheets.

[0021] S1-2: The MXene flakes obtained in S1-1 were dispersed in water, subjected to ultrasonic exfoliation and centrifugation, and the supernatant was collected to obtain a MXene dispersion.

[0022] Furthermore, the specific processing process of S2 is as follows:

[0023] S2-1: Aramid nanofibers were added to an organic solvent and magnetically stirred at 40°C for 2-24 h to obtain an ANF / DMSO dispersion.

[0024] S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath to quench precipitation, and then wash and ultrasonically disperse to obtain an ANF dispersion;

[0025] The precursor of the aramid nanofiber is 6 mm long aramid staple fiber, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to dimethyl sulfoxide solution is 1-3:550.

[0026] 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, a silver acetate solution or a silver molybdate solution with a silver ion concentration of 0.01-0.06 mol / l.

[0027] Furthermore, the specific process of S4 is as follows: the precursor dispersion obtained in S3 is dispersed by 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 mixture is reacted at a temperature of 25-80°C for 0.5 h to obtain a MXene@ANF@AgNPs composite dispersion.

[0028] The third object of the present invention is implemented by the following technical solution: a flexible energy storage battery, characterized in that a self-supporting flexible silver-rich electrode is used as the positive electrode, the negative electrode is a metal zinc or its alloy sheet, and the electrolyte is a hydrogel electrolyte.

[0029] The advantages of the present invention are as follows: (1) MXene is used for in-situ reduction deposition of silver ions. On the one hand, the functional groups on the surface of MXene sheets and the interlayer space provide good sites for the deposition of silver ions; on the other hand, the reducing property of MXene is used to reduce the silver ions. + Directly reduced to AgNPs on the surface of MXene, thereby achieving uniform dispersion and strong binding of silver nanoparticles in the electrode. (2) A small amount of ANF is introduced to construct a composite film with MXene. ANF, as a nano-reinforced fiber, forms a hydrogen bond cross-linking network between the MXene sheets, significantly improving the tensile strength and bending resistance of the composite film. This binder-free design avoids the problems of decreased conductivity and volume expansion that may be caused by traditional polymer binders, giving the electrode a higher conductive component content and better flexibility. (3) Post-treatment of the prepared composite electrode by appropriate drying or heat treatment methods can further improve the interface bonding and conductive contact between the MXene sheets and AgNPs and ANF, ensuring that the electrode remains stable under repeated mechanical deformation and long-term electrochemical cycles, and ensuring the conductivity and electrochemical stability of the electrode. (4) The present invention achieves a good electrochemical performance by "Ag +The preparation sequence is "first combined with ANF to form a precursor, then MXene is introduced for mild reduction to generate AgNPs." The resulting silver particles are evenly distributed in the ANF network and form a nested synergistic interaction with the ANF during the formation process. The AgNPs are embedded at the key nodes between the fibers and the sheets, playing the dual role of connecting the network pathways and enhancing the structural stability. At the same time, the MXene and ANF interact through hydrogen bonds to jointly construct a stable three-dimensional network structure. The mild reduction of MXene in situ induces the deposition of AgNPs at the interface between ANF and MXene. This not only precisely controls the growth position and distribution of the silver particles, but also achieves synergistic connection between the sheets and fibers without destroying the MXene structure. This preparation method effectively avoids problems such as particle agglomeration, insufficient bonding, 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.

[0030] The electrode material of the present invention overcomes many of the shortcomings of conventional 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 maintains excellent mechanical flexibility and structural stability while significantly increasing the silver content. Moreover, the electrode exhibits high specific capacity and long cycle life in flexible silver-zinc batteries, and can still be stably charged and discharged under repeated bending conditions. Therefore, the technical solution provided by the present invention is a high-performance, multifunctional flexible electrode material, which provides a new solution for flexible energy storage devices and related fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is the SEM image of the self-supporting flexible silver-rich electrode in Example 1.

[0032] Figure 2 This is a locally enlarged schematic diagram of the distribution of AgNPs in Example 1.

[0033] Figure 3 This is the resistance diagram of Example 1 after 10,000 bending tests.

[0034] Figure 4 This is a graph of the discharge capacity of Example 1 after 10,000 bending tests.

[0035] Figure 5 This is a diagram of the discharge capacity of the flexible energy storage battery of Example 7 after 6000 bending tests. DETAILED DESCRIPTION

[0036] Example 1: A self-supporting flexible silver-rich electrode comprising MXene sheets, aramid nanofibers, and silver nanoparticles. The MXene sheets and aramid nanofibers are interwoven to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed within the MXene / ANF framework. The mass ratio of MXene sheets, aramid nanofibers, and silver nanoparticles is 100:7.5:79. The MXene sheets are 1-2 μm in size; the aramid nanofibers have a diameter of 10-50 nm and a length of 1-150 μm. The silver nanoparticles are zero-valent silver particles generated in situ within the MXene / ANF framework, with a particle size of 5-50 nm.

[0037] After the self-supporting flexible silver-rich electrode of this embodiment was cut into several basic blocks, various experiments and studies were conducted. The specific results are as follows:

[0038] Take a piece of the basic block and observe it under a scanning electron microscope. Its structure is as follows Figure 1 As shown, from Figure 1 It can be seen that the self-supporting flexible silver-rich electrode prepared in this embodiment has a layered structure. Figure 2 This is a partially enlarged schematic diagram of the distribution of AgNPs in a self-supporting flexible silver-rich electrode generated using ChemDraw. It shows that silver nanoparticles are deposited on the MXene layers, forming a conductive lattice with uniform particle size and dense distribution. The AgNPs and MXene are tightly bound to achieve an excellent electron transport path. The figure also shows that ANF runs through the MXene layers, providing mechanical support and connecting the components through surface hydrogen bonds.

[0039] The basic block resistance of this embodiment is 0.45Ω / sq. A basic block is taken and subjected to a 180° bending test 10,000 times by a bending tester. The conductivity comparison before and after bending is shown in the figure below. Figure 3 As shown in the figure, after 10,000 bends, the resistance loss of the basic block only increased by 0.04Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this embodiment has strong bending resistance and good mechanical durability. Figure 4 As shown, at 0.8 mA cm -2 At a current density of 1.5 GHz, the discharge capacity retention rate is 90.9%, reflecting good capacitance stability.

[0040] In this embodiment, the surface resistance of the electrode film 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 after the bending test.

[0041] Example 2: A self-supporting flexible silver-rich electrode comprising MXene sheets, aramid nanofibers, and silver nanoparticles. The MXene sheets and aramid nanofibers are interwoven to form a MXene / ANF framework, and the silver nanoparticles are uniformly distributed within the MXene / ANF framework. The mass ratio of MXene sheets, aramid nanofibers, and silver nanoparticles is 100:2:25. The MXene sheets are 1-2 μm in size; the aramid nanofibers have a diameter of 10-50 nm and a length of 1-150 μm. The silver nanoparticles are zero-valent silver particles generated in situ within the MXene / ANF framework, with a particle size of 5-50 nm.

[0042] The basic square resistance of this embodiment is 0.45Ω / sq. A basic square was taken and subjected to a 180° bending test 10,000 times by a bending tester. The conductivity after bending was 0.46Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this embodiment has strong bending resistance and good mechanical durability. -2 At a current density of 1.5 GHz, the discharge capacity retention rate after bending is 95%, reflecting good capacitance stability.

[0043] Example 3: A self-supporting flexible silver-rich electrode comprising MXene sheets, aramid nanofibers, and silver nanoparticles. The MXene sheets and aramid nanofibers are interwoven to form a MXene / ANF framework, and the silver nanoparticles are evenly distributed within the MXene / ANF framework. The mass ratio of MXene sheets, aramid nanofibers, and silver nanoparticles is 100:20:100. The MXene sheets are 1-2 μm in size; the aramid nanofibers have a diameter of 10-50 nm and a length of 1-150 μm. The silver nanoparticles are zero-valent silver particles generated in situ within the MXene / ANF framework, with a particle size of 5-50 nm.

[0044] The basic square resistance of this embodiment is 1.5Ω / sq. A basic square was bent 10,000 times at 180° using a bending tester. The conductivity after bending was 1.6Ω / sq, indicating that the self-supporting flexible silver-rich electrode prepared in this embodiment has strong bending resistance and good mechanical durability. -2 At a current density of 1.5 GHz, the discharge capacity retention rate after bending is 85%, reflecting good capacitance stability.

[0045] Example 4: The method for preparing the self-supporting flexible silver-rich electrode described in Example 1 comprises the following steps:

[0046] S1: Preparation of MXene dispersion containing MXene sheets

[0047] S1-1: MXene sheets were obtained by chemical etching of 400-mesh MAX phase ceramics in HF solution at 35°C.

[0048] S1-2: The MXene flakes obtained in S1-1 were dispersed in water, subjected to ultrasonic exfoliation and centrifugation, and the supernatant was collected to obtain a MXene dispersion.

[0049] S2: preparing ANF dispersion containing aramid nanofibers;

[0050] S2-1: Aramid nanofibers were added to an organic solvent and magnetically stirred at 40 °C for 4 h to obtain an ANF / DMSO dispersion.

[0051] S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath to quench precipitation, and then wash and ultrasonically disperse to obtain an ANF dispersion;

[0052] The precursor of the aramid nanofiber is 6 mm long aramid staple fiber, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to dimethyl sulfoxide solution is 1.5:550.

[0053] S3: The ANF dispersion obtained in S2 is mixed with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: the ANF dispersion obtained in S2 is mixed with the silver ion solution and then stirred at room temperature to allow the surface functional groups of the aramid nanofibers to undergo complexation with the silver ions to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, a silver acetate solution or a silver molybdate solution with a silver ion concentration of 0.03 mol / l.

[0054] S4: Slowly add the MXene dispersion prepared in S1 to the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; the specific process is: the precursor dispersion obtained in S3 is magnetically stirred, and the MXene dispersion prepared in S1 is added at a rate of 5 ml per minute, and the mixture is reacted at a temperature of 50°C for 0.2h to obtain a MXene@ANF@AgNPs composite dispersion.

[0055] S5: The MXene@ANF@AgNPs composite dispersion obtained in S4 was subjected to vacuum filtration and rinsing treatment in sequence, and then dried and heat-treated in succession. The drying was carried out at 45°C for 1.5 hours, and the heat treatment was vacuum annealing at 400°C for 1 hour; a self-supporting flexible silver-rich electrode was obtained.

[0056] Example 5: The method for preparing the self-supporting flexible silver-rich electrode described in Example 2 comprises the following steps:

[0057] S1: Preparation of MXene dispersion containing MXene sheets

[0058] S1-1: Chemical etching was used to treat 400-mesh MAX phase ceramics in HF solution at 30°C to obtain MXene sheets;

[0059] S1-2: The MXene flakes obtained in S1-1 were dispersed in water, subjected to ultrasonic exfoliation and centrifugation, and the supernatant was collected to obtain a MXene dispersion.

[0060] S2: preparing ANF dispersion containing aramid nanofibers;

[0061] S2-1: Aramid nanofibers were added to an organic solvent and magnetically stirred at 40 °C for 2 h to obtain an ANF / DMSO dispersion.

[0062] S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath to quench and precipitate, and then wash and ultrasonically disperse to obtain an ANF dispersion;

[0063] Among them, the precursor of the aramid nanofiber is 6 mm long aramid staple fiber, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to dimethyl sulfoxide solution is 1:550.

[0064] S3: The ANF dispersion obtained in S2 is mixed with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: the ANF dispersion obtained in S2 is mixed with the silver ion solution and then stirred at room temperature to allow the surface functional groups of the aramid nanofibers to undergo complexation with the silver ions to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, a silver acetate solution or a silver molybdate solution with a silver ion concentration of 0.01 mol / l.

[0065] S4: Slowly add the MXene dispersion prepared in S1 to the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; the specific process is: ultrasonically disperse the precursor dispersion obtained in S3, and add the MXene dispersion prepared in S1 at a rate of 1 ml per minute, and react at a temperature of 25°C for 0.5h to obtain a MXene@ANF@AgNPs composite dispersion.

[0066] S5: The MXene@ANF@AgNPs composite dispersion obtained in S4 was subjected to vacuum filtration and rinsing treatments, and then dried and heat-treated in sequence. The drying was performed at 25°C for 2 hours, and the heat treatment was performed by vacuum annealing at 300°C for 1 hour; thus, a self-supporting flexible silver-rich electrode was obtained.

[0067] Example 6: The method for preparing the self-supporting flexible silver-rich electrode described in Example 3 comprises the following steps:

[0068] S1: Preparation of MXene dispersion containing MXene sheets

[0069] S1-1: Chemical etching of 400-mesh MAX phase ceramics in HF solution at 45°C to obtain MXene sheets;

[0070] S1-2: The MXene flakes obtained in S1-1 were dispersed in water, subjected to ultrasonic exfoliation and centrifugation, and the supernatant was collected to obtain a MXene dispersion.

[0071] S2: preparing ANF dispersion containing aramid nanofibers;

[0072] S2-1: Aramid nanofibers were added to an organic solvent and magnetically stirred at 40 °C for 24 h to obtain an ANF / DMSO dispersion.

[0073] S2-2: Pour the ANF / DMSO dispersion obtained in S2-1 into a water bath to quench precipitation, and then wash and ultrasonically disperse to obtain an ANF dispersion;

[0074] Among them, the precursor of the aramid nanofiber is 6 mm long aramid staple fiber, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to dimethyl sulfoxide solution is 3:550.

[0075] S3: The ANF dispersion obtained in S2 is mixed with a silver ion solution to obtain a precursor dispersion; the specific process is as follows: the ANF dispersion obtained in S2 is mixed with the silver ion solution and then stirred at room temperature to allow the surface functional groups of the aramid nanofibers to undergo complexation with the silver ions to obtain a precursor dispersion; the silver ion solution is a silver nitrate solution, a silver acetate solution or a silver molybdate solution with a concentration of 0.06 mol / l.

[0076] S4: Slowly add the MXene dispersion prepared in S1 to the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; the specific process is: the precursor dispersion obtained in S3 is magnetically stirred, and the MXene dispersion prepared in S1 is added dropwise at a rate of 10 ml per minute, and the mixture is reacted at a temperature of 80°C for 0.5h to obtain a MXene@ANF@AgNPs composite dispersion.

[0077] S5: The MXene@ANF@AgNPs composite dispersion obtained in S4 was subjected to vacuum filtration and rinsing treatments, and then dried and heat-treated in sequence. The drying was performed at 85°C for 1 hour, and the heat treatment was performed by vacuum annealing at 460°C for 1 hour; thus, a self-supporting flexible silver-rich electrode was obtained.

[0078] The preparation method of the present invention adopts the method of first introducing Ag +To construct the precursor system in the ANF dispersion, in the subsequent process of adding MXene, the reducing property of MXene is used to make Ag + Ag nanoparticles are generated in situ. The resulting silver particles are evenly distributed in the ANF network and undergo a nested synergistic effect with the ANF during the formation process. The embedded position of AgNPs is at the key node between the fiber and the sheet, playing the dual role of connecting the network pathway 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 induced to deposit at the interface between ANF and MXene in situ, which not only can accurately control the growth position and distribution state of silver particles, but also can achieve synergistic connection between the sheet and the fiber without destroying the MXene structure. This preparation method effectively avoids the problems of particle agglomeration, insufficient bonding or uneven conductivity, giving the film layer excellent conductivity, flexibility and electrochemical stability, and constructing a flexible composite conductive film with both structural integrity and performance synergy.

[0079] This three-phase synergistic mechanism enables AgNPs to not only exist as a conductive enhancing component, but also become a conductive node connecting ANF fibers and MXene sheets, thereby significantly enhancing the conductive path, flexibility and interfacial adhesion of the membrane structure.

[0080] Example 7: A flexible energy storage battery, using the self-supporting flexible silver-rich electrode described in Example 1 as the positive electrode, the negative electrode as metal zinc, and the electrolyte as a hydrogel electrolyte. The flexible energy storage battery prepared in this example has a current density of 0.8 mA cm -2 After 6000 180° bending tests at a current density of Figure 5 As shown in the figure, after the bending test, the discharge capacity retention rate was 91.8%, indicating that it has good electrochemical stability.

[0081] In some embodiments, the negative electrode of the flexible energy storage battery may also be a metal zinc alloy sheet.

[0082] In summary, this paper proposes a "MXene@ANF@AgNPs" composite system with a clear construction sequence and structural control strategy, focusing on the goal of synergistically improving the conductivity, flexibility, and electrochemical stability of flexible conductive electrodes. Compared with existing technologies, this system significantly improves upon the following aspects:

[0083] First, in terms of construction ideas, the present invention adopts "Ag + The sequential control strategy of first combining with ANF to form a precursor and then introducing MXene to mildly reduce and generate AgNPs avoids the problem of Ag +The structural destruction problem caused by direct reaction with MXene ensures good interface stability and synergistic bonding mechanism between the three components.

[0084] Secondly, in terms of structural characteristics, 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 framework-sheet conductive channels". This network not only improves the electron transmission efficiency, but also enhances the mechanical integrity and durable deformation resistance of the flexible film.

[0085] Thirdly, in terms of preparation control, the present invention achieves precise control of the distribution position, particle size and embedding depth of silver particles, avoiding structural stability defects such as AgNPs agglomeration, layer peeling or interface delamination in comparative technologies, thereby obtaining an integrated electrode material with balanced performance.

[0086] Finally, in terms of actual performance, the flexible electrode film prepared by the present invention exhibits extremely low surface resistance, excellent flexible deformation retention, and a capacity retention rate of up to 90.9% after bending.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, 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: The invention relates to a novel nanostructured polymer composite material comprising MXene sheets, aramid nanofibers and silver nanoparticles. The MXene sheets and the aramid nanofibers are interwoven to form a MXene / ANF skeleton, and the silver nanoparticles are uniformly distributed in the MXene / ANF skeleton. The mass ratio of the MXene sheets, the aramid nanofibers and the silver nanoparticles is 100:2-20:25-100.

2. A self-supporting flexible silver-rich electrode according to claim 1, characterized in that: The MXene sheet size is 1-2 μm.

3. The self-supporting flexible silver-rich electrode according to claim 1, characterized in that: The aramid nanofiber has a diameter of 10-50 nm and a length of 1-150 μm.

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

5. The method for preparing a self-supporting flexible silver-rich electrode according to any one of claims 1 to 4, characterized in that: The steps include: S1: Preparation of MXene dispersion containing MXene sheets; S2: preparing ANF dispersion containing aramid nanofibers; S3: mixing the ANF dispersion obtained in S2 with the silver ion solution to obtain a precursor dispersion; S4: Slowly add the MXene dispersion prepared in S1 to the precursor dispersion to obtain a MXene@ANF@AgNPs composite dispersion; S5: The MXene@ANF@AgNPs composite dispersion obtained in S4 is subjected to vacuum filtration, rinsing, drying and heat treatment to obtain a self-supporting flexible silver-rich electrode; In S5, the drying temperature is 25-80° C. and the drying time is 1-2 h, and the heat treatment is vacuum annealing at 300-450° C. for 1 h.

6. The method for preparing a self-supporting flexible silver-rich electrode according to claim 5, characterized in that: The S1 comprises the following steps: S1-1: Chemical etching was performed on 400-mesh MAX phase ceramics in a 30-45°C HF solution to obtain MXene sheets. S1-2: The MXene flakes obtained in S1-1 were dispersed in water, subjected to ultrasonic exfoliation and centrifugation, and the supernatant was collected to obtain a MXene dispersion.

7. The method for preparing a self-supporting flexible silver-rich electrode according to claim 5, characterized in that: The specific processing process of S2 is as follows: S2-1: Aramid nanofibers were added to an organic solvent and magnetically stirred 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 to quench and precipitate, and then wash and ultrasonically disperse to obtain an ANF dispersion; The precursor of the aramid nanofiber is 6 mm long aramid staple fiber, the organic solvent is a dimethyl sulfoxide solution containing potassium hydroxide, and the mass ratio of potassium hydroxide to dimethyl sulfoxide solution is 1-3:

550.

8. The method for preparing a self-supporting flexible silver-rich electrode according to claim 5, characterized in that: 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, a silver acetate solution or a silver molybdate solution with a silver ion concentration of 0.01-0.06 mol / l.

9. The method for preparing a self-supporting flexible silver-rich electrode according to claim 5, characterized in that: The specific process of S4 is as follows: the precursor dispersion obtained in S3 is dispersed by magnetic stirring or ultrasonic dispersion, and the MXene dispersion obtained in S1 is added dropwise at a rate of 1-10 ml per minute, and the mixture is reacted 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: The self-supporting flexible silver-rich electrode according to any one of claims 1 to 4 is used as the positive electrode, the negative electrode is a metal zinc or alloy sheet thereof, and the electrolyte is a hydrogel electrolyte.

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