Electrochromic fiber with fast response performance and preparation method thereof

Abstract

The application provides an electrochromic fiber with fast response performance and a preparation method thereof. The electrochromic fiber comprises a fiber substrate, a reticular nanostructured electrochromic material attached to the surface of the fiber substrate, and a gel electrolyte layer wrapped on the surface of the electrochromic material, and the electrochromic material is connected to the fiber substrate through a chemical bond. The reticular nanostructure in the electrochromic fiber is beneficial to ion transmission and electron injection, improves the response speed of the electrochromic material, and also makes ions diffuse quickly, provides a larger surface area for charge transfer reaction, and comprehensively improves the electrochromic performance of the fiber. The electrochromic fiber based on vanadium pentoxide has stable driving voltage, can display different colors with the change of voltage, has the characteristics of bright color, high sensitivity, good cycle stability, and long color memory, and the preparation method is simple, does not need to add other medicaments, has low cost, and is suitable for industrialized production.

Description

Technical Field

[0001] This invention relates to the field of electrochromic fiber technology, and in particular to an electrochromic fiber with rapid response performance and its preparation method. Background Technology

[0002] Electrochromism is a phenomenon where the optical properties of a material (reflectivity, transmittance, absorptivity, etc.) undergo stable and reversible color changes under the influence of an applied electric field. This manifests as reversible changes in color and transparency. Materials exhibiting electrochromic properties are called electrochromic materials, and devices made from electrochromic materials are called electrochromic devices. Currently, electrochromic devices have a wide range of applications, including common fields such as smart windows, optical filters, and electronic displays. Furthermore, with continuous advancements in technology, electrochromic materials are gradually expanding into areas such as smart homes, wearable displays, and visual detection.

[0003] Combining electrochromic technology with fibers to develop fibers with electrochromic functions and applying them to various smart textiles with color-responsive behavior will bring enormous academic and industrial value and promote the development of smart fabric materials.

[0004] In the prior art, an invention patent (application number CN 202310491325.3) discloses a V2O5-based electrochromic material, its preparation method, and an electrochromic device. The method involves first mixing vanadium salt with a polar solvent to obtain a vanadium salt solution, then heating the vanadium salt solution to obtain a V2O5-based precursor, and finally annealing the V2O5-based precursor in an oxygen-containing atmosphere to obtain the V2O5-based electrochromic material. Although this electrochromic material exhibits good mobility and does not require a device or all-solid-state structure, allowing for the fabrication of electrochromic devices through spraying, printing, or pasting, these methods are unsuitable for preparing electrochromic fabrics. Spraying, printing, or pasting can adversely affect the original mechanical properties and wearing comfort of the fabric. Furthermore, since the electrochromic material is physically attached to the fabric surface, its response speed is significantly reduced and gradually decays with prolonged use.

[0005] In view of this, it is necessary to design an improved electrochromic fiber with fast response performance and its preparation method to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an electrochromic fiber with rapid response performance and its preparation method. The method uses flexible conductive fiber as a substrate, which is treated and then immersed in a specific vanadium oxysulfate system to form a network nanostructure electrochromic material on its surface. The electrochromic fiber is then coated with a gel electrolyte to obtain the electrochromic fiber. This invention overcomes the problem of reduced fiber mechanical properties and comfort caused by the adhesion of electrochromic material in the prior art, and solves the drawbacks of poor response speed and decreased response performance with use of the fabric in electrochromic fibers.

[0007] To achieve the above-mentioned objective, the present invention provides an electrochromic fiber with fast response performance. The electrochromic fiber includes a fiber matrix, an electrochromic material attached to the surface of the fiber matrix, and a gel electrolyte layer wrapped around the surface of the electrochromic material. The electrochromic material is connected to the fiber matrix by chemical bonds, and the electrochromic material is a layered network nanostructure.

[0008] As a further improvement of the present invention, the electrochromic material is composed of vanadium pentoxide, and the diameter of the network nanostructure is 60-100 nm.

[0009] As a further improvement of the present invention, the response time of the electrochromic fiber is 3-5 seconds, and the electrochromic efficiency is 50 cm⁻¹. 2 / C and above.

[0010] As a further improvement of the present invention, the fiber matrix is ​​a flexible conductive fiber, including one or more of carbon fiber, stainless steel fiber, nickel-plated copper wire fiber, silver-plated nylon fiber, and nickel-plated cotton fiber, as well as fiber bundles composed thereof.

[0011] The present invention also provides a method for preparing the electrochromic fiber with fast response performance as described above, comprising the following steps:

[0012] S1. The fibers are subjected to surface treatment and hydrophilic treatment in sequence, so that hydroxyl groups are attached to the surface of the fibers;

[0013] S2. Prepare a vanadium oxysulfate solution with a concentration of 0.3-0.6 mol / L, wherein the solvent of the vanadium oxysulfate solution is a mixed solvent of deionized water and anhydrous ethanol;

[0014] S3. The fiber treated in step S1 is immersed in the vanadium oxysulfate solution in step S2. The temperature of the vanadium oxysulfate solution is maintained at 30-80°C by external heating for 5-18 hours, so that vanadium pentoxide grows naturally on the fiber surface, resulting in a fiber with a network nanostructure on the surface.

[0015] S4. The fibers with a mesh-like nanostructure on the surface obtained in step S3 are completely coated with a gel electrolyte and dried to obtain an electrochromic fiber with fast response performance.

[0016] As a further improvement of the present invention, in step S2, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is (0.9-1.2):1.

[0017] As a further improvement of the present invention, in step S1, the hydrophilic treatment is to use the surface-treated fiber as the positive electrode, the platinum electrode as the negative electrode, and the potassium hydroxide solution as the electrolyte, and then perform electrochemical treatment to obtain fibers with hydroxyl groups attached to the surface.

[0018] As a further improvement of the present invention, in step S4, the gel electrolyte is prepared by mixing a propylene carbonate solution containing 10 wt% lithium perchlorate and 25 wt% polymethyl methacrylate, and stirring and heating in a water bath at 75-80°C for 8-10 hours.

[0019] As a further improvement of the present invention, the concentration of the electrolyte sodium hydroxide solution is 1.5-3 mol / L, the energizing time is 5-8 min, and the voltage is 6-8 V.

[0020] As a further improvement of the present invention, in step S1, the surface treatment step is as follows: the fiber to be treated is placed in a beaker containing anhydrous ethanol solution, ultrasonically vibrated for 10-15 minutes, then taken out, rinsed with deionized water and dried to obtain a clean fiber.

[0021] The beneficial effects of this invention are:

[0022] 1. The electrochromic fiber with rapid response performance of the present invention includes a fiber matrix, an electrochromic material attached to the surface of the fiber matrix, and a gel electrolyte layer wrapped around the surface of the electrochromic material. The electrochromic material and the fiber matrix are connected by chemical bonds, and the electrochromic material is a layered network nanostructure. The present invention uses flexible conductive fiber as the substrate, which is treated and then immersed in a specific vanadium oxysulfate system to form a network nanostructure electrochromic material on its surface. The electrochromic fiber is then coated with a gel electrolyte to obtain the electrochromic fiber. This overcomes the problem of reduced fiber mechanical properties and comfort caused by the attachment of electrochromic material in the prior art, and solves the drawbacks of poor response speed and decreased response performance with fabric use in electrochromic fibers. This preparation method and the obtained electrochromic fiber have good application prospects in the field of smart wearables.

[0023] 2. This invention hydrophilically treats the fibers by applying a high potential to the fibers in a short time, increasing the number of active groups on the fiber surface and binding hydrophilic oxygen-containing functional groups on the fiber surface, making the fiber surface superhydrophilic and obtaining a highly electrochemically active surface. After immersing the fibers in a vanadium oxysulfate solution system, under the action of the oxygen-containing functional groups of ethanol in the solution, vanadium oxide reacts with the hydroxyl groups on the fiber surface to generate nuclei. After the nuclei are generated, vanadium oxide continues to grow along the nuclei, thereby naturally growing into a very regular and uniform network nanostructure on the fiber surface. This network nanostructure is more conducive to ion transport and electron injection, improving the response speed of the electrochromic material. In addition, the network nanostructure enables rapid ion diffusion and provides a larger surface area for charge transfer reactions, comprehensively improving the electrochromic performance of the electrochromic fiber.

[0024] 3. The preparation method of this invention requires no additional reagents, resulting in low cost and a simple preparation process. Electrochromic materials can be formed on the fiber surface without strong intervention, making it suitable for industrial mass production. The vanadium pentoxide-based electrochromic fiber exhibits stable driving voltage and displays different colors with voltage changes, characterized by vivid colors, high sensitivity, good cycle stability, and long-term color memory. Furthermore, the electrochromic fiber with flexible conductive fiber as its matrix possesses excellent controllability and flexibility, offering significant advantages in flexible displays such as flexible sensing and smart wearables. Attached Figure Description

[0025] Figure 1 The image shows an electron microscope image of the stainless steel fiber matrix used in Example 1.

[0026] Figure 2 Electron microscopy morphology of stainless steel fibers with a mesh-like nanostructure on the surface prepared in Example 1.

[0027] Figure 3 The CV cycle curve of the electrochromic stainless steel fiber prepared in Example 1 is shown.

[0028] Figure 4 The chronoamperometry cyclic test curve of the electrochromic stainless steel fiber prepared in Example 1 is shown.

[0029] Figure 5 The image shows a color comparison of the electrochromic stainless steel fibers prepared in Example 1 under different voltages.

[0030] Figure 6 Electron micrograph of cotton fibers with a mesh-like nano-sea urchin structure on the surface prepared in Example 2. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0033] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0034] An electrochromic fiber with rapid response performance includes a fiber matrix, an electrochromic material attached to the surface of the fiber matrix, and a gel electrolyte layer encapsulating the surface of the electrochromic material. The electrochromic material and the fiber matrix are connected by chemical bonds, and the electrochromic material is a layered network nanostructure. The electrochromic material is composed of vanadium pentoxide, and the diameter of the network nanostructure is 60-100 nm. It should be noted that the diameter of this network nanostructure is the diameter of the fiber filaments that make up the network nanostructure. The fiber matrix and the electrochromic material in this electrochromic fiber are connected by chemical bonds. Compared with the physical bonding methods such as coating and bonding in the prior art, this method improves the structural integrity of the electrochromic fiber and does not adversely affect the mechanical properties and flexibility of the fiber matrix, resulting in good recyclability of the electrochromic fiber.

[0035] When applied, the network nanostructure of this electrochromic fiber is more conducive to ion transport and electron injection, improving the response speed of the electrochromic material. Furthermore, the network nanostructure facilitates rapid ion diffusion and provides a larger surface area for charge transfer reactions, comprehensively enhancing the electrochromic performance of the fiber. This results in a response time of 3–5 seconds and an electrochromic efficiency of 50 cm⁻¹. 2 / C and above.

[0036] In some specific embodiments, the fiber matrix is ​​a flexible conductive fiber, including one or more of carbon fiber, stainless steel fiber, nickel-plated copper wire fiber, silver-plated nylon fiber, and nickel-plated cotton fiber, as well as fiber bundles composed of such fibers.

[0037] Electrochromic fibers based on vanadium pentoxide have stable driving voltage, fast response speed, and can display different colors with changes in voltage. They are characterized by bright colors, high sensitivity, good cycle stability, and long-term color memory. Furthermore, electrochromic fibers based on flexible conductive fibers have good controllability and flexibility, which will have great application advantages in flexible displays such as flexible sensing and smart wearables.

[0038] A method for preparing an electrochromic fiber with fast response performance includes the following steps:

[0039] S1. The fibers are subjected to surface treatment and hydrophilic treatment in sequence, so that hydroxyl groups are attached to the surface of the fibers.

[0040] S2. Prepare a vanadium oxysulfate solution with a concentration of 0.3-0.6 mol / L. The solvent for the vanadium oxysulfate solution is a mixture of deionized water and anhydrous ethanol.

[0041] S3. The fiber treated in step S1 is immersed in the vanadium oxysulfate solution in step S2. The temperature of the vanadium oxysulfate solution is maintained at 30-80°C by external heating for 5-18 hours, so that vanadium pentoxide grows naturally on the fiber surface, resulting in a fiber with a network nanostructure on the surface.

[0042] S4. The fibers with a mesh-like nanostructure on the surface obtained in step S3 are completely coated with a gel electrolyte and dried to obtain an electrochromic fiber with fast response performance.

[0043] Specifically, this method first hydrophilically treats the fibers by applying a high potential to the fibers for a short time, increasing the number of active groups on the fiber surface and binding hydrophilic oxygen-containing functional groups on the fiber surface, making the fiber surface superhydrophilic and obtaining a highly electrochemically active surface. After immersing the fibers in a vanadium oxysulfate solution system, under the action of the oxygen-containing functional groups of ethanol in the solution, vanadium oxide reacts with the hydroxyl groups on the fiber surface to generate nuclei. After the nuclei are generated, vanadium oxide continues to grow along the nuclei, thereby naturally growing into a very regular and uniform network nanostructure on the fiber surface. This network nanostructure enhances the overall conductivity of the fiber and improves the response speed of the electrochromic fiber.

[0044] The electrochromic fiber prepared by the method of this invention has good flexibility, stable color-changing properties and excellent color memory properties. It overcomes the problem of reduced fiber mechanical properties and comfort caused by the adhesion of electrochromic materials in the prior art, and solves the drawbacks of poor response speed and decay of response performance with use of the fabric in electrochromic fibers. The preparation method and the obtained electrochromic fiber have good application prospects in the field of smart wearables.

[0045] Specifically, in step S2, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is (0.9–1.2):1. The reason for using deionized water and anhydrous ethanol as solvents for vanadium oxysulfate is that vanadium oxysulfate is soluble in deionized water, and the oxygen-containing functional groups in ethanol can enhance the interaction between vanadium oxide and the surface groups of the substrate, which helps to form a network nanostructure.

[0046] In step S1, the hydrophilic treatment involves using the surface-treated fiber as the positive electrode, a platinum electrode as the negative electrode, and a potassium hydroxide solution as the electrolyte. Electrolysis is applied to the fiber to obtain fibers with hydroxyl groups attached to their surface. Thus, under the influence of electricity, anions in the electrolyte adhere to the surface of the fiber, resulting in fibers with a large number of hydroxyl groups attached to their surface.

[0047] In some specific embodiments, the concentration of the electrolyte sodium hydroxide solution is 1.5–3 mol / L, the energizing time is 5–8 min, and the voltage is 6–8 V.

[0048] More specifically, in step S4, the gel electrolyte is prepared by mixing a propylene carbonate solution containing 10 wt% lithium perchlorate and 25 wt% polymethyl methacrylate, and heating and stirring in a water bath at 75–80°C for 8–10 hours. This gel electrolyte can provide ClO4 for the electrochromic process of vanadium pentoxide. - and Li + .

[0049] In step S1, the surface treatment steps are as follows: the fiber to be treated is placed in a beaker containing anhydrous ethanol solution, ultrasonically vibrated for 10-15 minutes, then taken out, rinsed with deionized water and dried to obtain a clean fiber.

[0050] The above preparation method does not require the addition of other reagents, has low cost, and is simple in preparation process. It can form electrochromic materials on the fiber surface without other strong intervention, making it suitable for industrial mass production.

[0051] Example 1

[0052] This embodiment provides an electrochromic fiber with fast response performance and its preparation method, including the following steps:

[0053] S1. Place the stainless steel fiber in anhydrous ethanol for ultrasonic cleaning for 15 minutes to ensure that it is clean in the previous step. Then, use the cleaned fiber as the anode and the platinum electrode as the cathode, and put it into a 1.8 mol / L potassium hydroxide solution and pass a 6V voltage for 5 minutes. After the fiber is dried at room temperature, store it for later use.

[0054] S2. Mix anhydrous ethanol and deionized water in a 1:1 volume ratio to obtain a mixed solvent, then add vanadium oxysulfate to the mixed solvent to prepare a vanadium oxysulfate solution with a concentration of 0.4 mol / L.

[0055] S3. The fiber treated in step S1 is immersed in the vanadium oxysulfate solution in step S2, and the container is placed on a heating platform to keep the vanadium oxysulfate solution at 45°C for 15 hours, so that vanadium pentoxide grows naturally on the fiber surface to obtain stainless steel fiber with a mesh nanostructure on the surface. After taking it out, it is rinsed with anhydrous ethanol and dried for later use.

[0056] S4. Dry lithium perchlorate at 120°C for 24 hours, and dry polymethyl methacrylate particles at 80°C for 24 hours; dissolve a certain amount of lithium perchlorate in propylene carbonate solution, stir thoroughly, and prepare a 10wt% LiClO4:PC solution to form a liquid electrolyte; add polymethyl methacrylate particles to the above electrolyte solution, and stir continuously at 80°C for 8 hours to form a gel electrolyte;

[0057] S5. The fiber with a mesh-like nanostructure on its surface obtained in step S3 is immersed in the gel electrolyte prepared in step S4. One end of the fiber is left unreserved by 5 mm, and the rest is completely covered by the gel electrolyte. After drying, an electrochromic fiber with fast response performance is obtained.

[0058] Please see Figures 1-2 As shown, Figure 1 The image shows an electron microscope image of the stainless steel fiber matrix used in Example 1. As can be seen from the image, the surface of the stainless steel fiber is smooth before treatment. Figure 2 The image shows the electron microscope morphology of the stainless steel fiber with a mesh nanostructure on its surface prepared in Example 1. As can be seen from the image, a very regular and uniform mesh nanostructure is formed on the surface of the fiber, and the composite effect between the mesh nanostructure and the fiber matrix is ​​good. The electrochromic fiber has good structural integrity.

[0059] Please see Figure 3 The figure shows the CV cycle curve of the electrochromic stainless steel fiber prepared in Example 1. As can be seen from the figure, vanadium pentoxide exhibits obvious redox peaks, indicating that the redox reaction of the vanadium pentoxide electrochromic layer is reversible.

[0060] Please see Figure 4 The figure shows the chronoamperometry cyclic test curve of the electrochromic stainless steel fiber prepared in Example 1. It can be seen from the figure that the maximum current density of the electrochromic stainless steel fiber remains essentially unchanged within 50 cycles, maintaining at 40 mA / cm². 2 The left and right figures indicate that the electrochromic fiber prepared in this embodiment, which has fast response performance, also has good electrochemical stability.

[0061] Please see Figure 5The figure shows a color comparison of the electrochromic stainless steel fiber prepared in Example 1 under different voltages. As can be seen from the figure, the fiber is yellow when the voltage is 1V, and turns dark blue when the voltage is -1V, exhibiting a good color effect and relatively uniform color development.

[0062] Example 2

[0063] This embodiment provides an electrochromic fiber with fast response performance and its preparation method. Compared with Embodiment 1, the difference is that nickel-plated cotton fiber is used instead of stainless steel fiber. In step S3, the processing time is 18 hours, and the rest is roughly the same as in Embodiment 1, which will not be repeated here.

[0064] Please see Figure 6 The image shown is an electron microscope image of the cotton fiber with a mesh-like nano-sea urchin structure on its surface prepared in Example 2. As can be seen from the image, the surface of the cotton fiber is a morphological structure tightly coated with mesh-like vanadium pentoxide. Compared with Example 1, as time goes on, the thinner mesh-like nanostructure is stacked into a thicker mesh-like nano-sea urchin structure, and the structure is evenly distributed and tightly combined with the fiber substrate, so that the electrochromic cotton fiber will not have the problem of surface electrochromic material falling off during application.

[0065] Comparative Example 1

[0066] Comparative Example 1 provides an electrochromic fiber and its preparation method. The difference from Example 1 is that in step S2, the solvent of the vanadium oxysulfate solution is pure deionized water. The rest is roughly the same as in Example 1 and will not be repeated here.

[0067] Comparative Example 2

[0068] Comparative Example 2 provides an electrochromic fiber and its preparation method. The difference from Example 1 is that the stainless steel fiber is not hydrophilic treated in step S1. The rest is roughly the same as Example 1 and will not be described again here.

[0069] Comparative Example 3

[0070] Comparative Example 3 provides an electrochromic fiber and its preparation method. Compared with Example 1, the difference is that the electrochromic fiber is prepared by coating method, specifically by coating the V2O5-based electrochromic material disclosed in the patent application number CN 202310491325.3 in the background art onto the surface of stainless steel fiber.

[0071] The electrochromic fibers prepared in Examples 1-2 and Comparative Examples 1-3 were tested for electrochromic efficiency, response performance and mechanical properties. The results are shown in Table 1.

[0072] Table 1. Test results of electrochromic fiber properties in Examples 1-2 and Comparative Examples 1-3

[0073]

[0074]

[0075] As shown in Table 1, the electrochromic fibers prepared in Examples 1 and 2 exhibited good electrochromic efficiency and response performance. Compared to stainless steel fibers, the coloring and bleaching time of vanadium pentoxide electrochromic fibers with nickel-plated cotton fibers as the substrate was slightly increased. A comparison of the tensile strength between Example 1 and Comparative Examples 1-3 shows that the preparation method in Example 1 did not damage the mechanical properties of the fibers. In Comparative Example 1, pure deionized water was used to prepare the solution. The absence of oxygen-containing functional groups provided by ethanol to promote the growth of vanadium pentoxide resulted in an uneven electrochromic layer, leading to low electrochromic efficiency. Furthermore, due to the uneven and thin electrochromic layer, the coloring and bleaching times of the sample prepared in Comparative Example 1 were relatively short. In Comparative Example 2, the stainless steel fibers were not hydrophilically treated, preventing vanadium pentoxide from nucleating and growing on their surface, thus preventing the synthesis of an electrochromic layer. In Comparative Example 3, the solution prepared could not coat vanadium pentoxide onto the fiber surface, resulting in the fibers in Comparative Example 3 exhibiting characteristics of the substrate fiber.

[0076] Example 3

[0077] This embodiment provides an electrochromic fiber with fast response performance and its preparation method. Compared with Example 1, the difference is that in step S3, the temperature of the vanadium oxysulfate solution is 60°C. The rest is roughly the same as in the example, and will not be repeated here.

[0078] Comparative Example 4

[0079] Comparative Example 4 provides an electrochromic fiber with fast response performance and its preparation method. The difference from Example 1 is that in step S3, the temperature of the vanadium oxysulfate solution is 90°C. The rest is roughly the same as the example, and will not be repeated here.

[0080] Example 4

[0081] This embodiment provides an electrochromic fiber with fast response performance and its preparation method. Compared with Embodiment 1, the difference is that in step S3, the time is 8 hours. The rest is roughly the same as the embodiment, and will not be repeated here.

[0082] Comparative Example 5

[0083] Comparative Example 5 provides an electrochromic fiber with fast response performance and its preparation method. The difference from Example 1 is that the time in step S3 is 3 hours. The rest is roughly the same as the Example, and will not be repeated here.

[0084] Comparative Example 6

[0085] Comparative Example 6 provides an electrochromic fiber with fast response performance and its preparation method. Compared with Example 1, the difference is that in step S2, the concentration of vanadium oxysulfate solution is 0.1 mol / L. The rest is roughly the same as the example, and will not be repeated here.

[0086] Comparative Example 7

[0087] Comparative Example 7 provides an electrochromic fiber with fast response performance and its preparation method. Compared with Example 1, the difference is that in step S2, the concentration of vanadium oxysulfate solution is 0.8 mol / L. The rest is roughly the same as the example, and will not be repeated here.

[0088] The electrochromic fibers prepared in Examples 3-4 and Comparative Examples 4-7 were tested for electrochromic efficiency and response performance. The results are shown in Table 2.

[0089] Table 2. Test results of electrochromic fiber properties in Examples 3-4 and Comparative Examples 4-7

[0090] <![CDATA[Electrochromic efficiency (cm 2 / C)]]> Coloring time (s) Bleaching time (s) Example 3 70.83 4.5 5.3 Example 4 62.56 3.1 3.8 Comparative Example 4 69.83 4.7 6.1 Comparative Example 5 0 0 0 Comparative Example 6 53.47 3.5 3.7 Comparative Example 7 68.96 5.1 6.3

[0091] As shown in Table 2, in Examples 3 and 4, when the preparation temperature is increased, the polymerization rate is accelerated due to the increased temperature, resulting in a thicker and denser electrochromic layer, which leads to a decrease in electrochromic efficiency and an increase in coloring and bleaching time. In Example 4, when the preparation time is shortened, vanadium pentoxide cannot form a uniform network structure, and as in Comparative Example 5, vanadium pentoxide may not have enough time to grow on the substrate surface, resulting in a decrease in electrochromic efficiency. In Comparative Example 6, when the precursor concentration is reduced, the vanadium ion concentration in the solution is low, resulting in an uneven and thin electrochromic layer with only a thin film morphology, unable to grow a network structure, thus reducing the color change efficiency. Due to its thin film, the coloring and bleaching time is relatively short. In Comparative Example 7, when the precursor concentration is increased, the vanadium ion concentration in the solution is too high, resulting in a thicker and denser electrochromic layer, thus reducing the color change efficiency.

[0092] In summary, this invention provides an electrochromic fiber with rapid response performance and its preparation method. The electrochromic fiber includes a fiber matrix, an electrochromic material attached to the surface of the fiber matrix, and a gel electrolyte layer encapsulating the surface of the electrochromic material. The electrochromic material and the fiber matrix are connected by chemical bonds, and the electrochromic material is a layered network nanostructure. This invention uses flexible conductive fiber as the substrate, which is treated and then immersed in a specific vanadium oxysulfate system to form a network nanostructure electrochromic material on its surface. The electrochromic fiber is then coated with a gel electrolyte. The network nanostructure of the electrochromic material is more conducive to ion transport and electron injection, improving the response speed of the electrochromic material. It also allows for rapid ion diffusion, providing a larger surface area for charge transfer reactions, thus comprehensively improving the electrochromic performance of the electrochromic fiber. The electrochromic fiber based on vanadium pentoxide of this invention has a stable driving voltage and can display different colors with changes in voltage. It features bright colors, high sensitivity, good cycle stability, and long-term color memory. It overcomes the problem of reduced fiber mechanical properties and comfort caused by the adhesion of electrochromic materials in the prior art, and solves the drawbacks of poor response speed and decay of response performance with use of fabrics. This electrochromic fiber and its preparation method have good application prospects in the field of smart wearables.

[0093] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for producing an electrochromic fiber having a fast response performance, characterized by, The method comprises the following steps: S1, sequentially performing surface treatment and hydrophilic treatment on the fiber, so that hydroxyl groups are attached to the surface of the fiber; S2, preparing a vanadyl sulfate solution with a concentration of 0.3-0.6 mol / L, wherein the solvent of the vanadyl sulfate solution is a mixed solvent of deionized water and anhydrous ethanol; S3, soaking the fiber treated in step S1 in the vanadyl sulfate solution in step S2, and using external heating to heat the vanadyl sulfate solution to a temperature of 30-80 ℃ for 15-18 h, so that vanadium pentoxide grows naturally on the surface of the fiber, thereby obtaining a fiber with a reticular nanostructure attached to the surface; S4, completely coating the fiber with the reticular nanostructure attached to the surface obtained in step S3 with a gel electrolyte, and drying to obtain an electrochromic fiber with fast response performance.

2. The production method according to claim 1, characterized by, In step S2, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is (0.9-1.2):

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the hydrophilic treatment is performed by using the fiber after surface treatment as a positive electrode, a platinum electrode as a negative electrode, and a potassium hydroxide solution as an electrolyte, and then performing electric treatment to obtain a fiber with hydroxyl groups attached to the surface.

4. The method of claim 1, wherein, In step S4, the gel electrolyte is prepared by mixing a propylene carbonate solution containing 10 wt% lithium perchlorate and 25 wt% polymethyl methacrylate, and then stirring and heating in a water bath at 75-80 ℃ for 8-10 h.

5. The preparation method according to claim 3, characterized in that, The concentration of the potassium hydroxide solution is 1.5-3 mol / L, the electric treatment time is 5-8 min, and the voltage is 6-8 V.

6. The method of claim 1, wherein, In step S1, the surface treatment is performed by placing the fiber to be treated in a beaker containing anhydrous ethanol solution, ultrasonically oscillating for 10-15 min, then taking it out, rinsing with deionized water, and drying to obtain a fiber with a clean surface.

7. An electrochromic fiber having fast response performance, characterized by The electrochromic fiber is prepared by the preparation method in any one of claims 1-6, and comprises a fiber substrate, an electrochromic material attached to the surface of the fiber substrate, and a gel electrolyte layer wrapped on the surface of the electrochromic material, wherein the electrochromic material is connected to the fiber substrate by a chemical bond, and the electrochromic material is a reticular nanostructure in a stacked form.

8. The electrochromic fiber having a fast response performance according to claim 7, characterized by, The electrochromic material comprises vanadium pentoxide, and the diameter of the reticular nanostructure is 60-100 nm.

9. The electrochromic fiber having a fast response performance according to claim 7, characterized by, The electrochromic fiber has a response time of 3-5 s and an electrochromic efficiency of 50 cm 2 / C or more.

10. The electrochromic fiber having a fast response performance according to claim 7, characterized by, The fiber substrate is a flexible conductive fiber, which comprises one or more of carbon fiber, stainless steel fiber, nickel-plated copper wire fiber, silver-plated nylon fiber, and nickel-plated cotton fiber, and a fiber bundle composed of the above fibers.

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