Reflection type flexible electrochromic device based on hydrogel electrolyte, preparation method and application

Abstract

The invention relates to the technical field of electrochromism devices, in particular to a reflective flexible electrochromism device based on hydrogel electrolyte, a preparation method and application. The electrochromic device comprises a first conductive substrate and a second conductive substrate, and the first conductive substrate and the second conductive substrate are oppositely arranged; a hydrogel electrolyte layer is attached to one side of the first conductive substrate, an electrochromic layer is attached to one side of the second conductive substrate, and the hydrogel electrolyte layer and the electrochromic layer are attached to each other; convex structures are formed on the mutually attached surfaces of the hydrogel electrolyte layer and the electrochromism layer, and convex structures are formed on the hydrogel electrolyte layer and the electrochromism layer through porous polystyrene templates. The electrochromic device prepared by the method is high in interfacial compatibility and small in color difference formed on the surface.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic devices, and in particular to a reflective flexible electrochromic device based on a hydrogel electrolyte, a preparation method and an application thereof. Background Art

[0002] Electrochromism refers to the phenomenon that the optical properties of a material or device undergo a stable and reversible color change under the action of an external electric field, which is manifested in the appearance as a reversible change in color and transparency. The characteristic of electrochromic devices to achieve color change under external stimuli gives them obvious application advantages in certain specific occasions. Electrochromic devices mainly include a five-layer structure: bottom conductive electrode / ion storage layer / ion electrolyte layer / electrochromic layer / top conductive electrode, which is a typical optoelectronic multifunctional device. When a certain positive and negative voltage is applied to both ends of the device electrode, ions and free electrons are constantly moving inside and outside the device, so that the device has a spectral control function. At present, electrochromic technology has been widely used in many fields such as smart windows, aerospace vehicles, automotive rearview mirrors, smart displays, information storage devices and sensors.

[0003] At present, the research on electrochromic devices is mainly focused on transmissive devices, while there is relatively little research on reflective flexible electrochromic devices. At present, the process structure of preparing reflective electrochromic devices is complex, the cost is high, and there is a lack of flexibility. Flexible electrochromic devices have high requirements for reflective layer materials, which will limit the widespread application of electrochromic devices to a certain extent. In order to improve the overall performance of reflective flexible electrochromic devices, most of the research focuses on the design and preparation of high-performance electrochromic layer materials, and less research is done on the exploration and design of high-performance electrolyte layers that meet the requirements. The electrolyte layer is located between the upper and lower electrodes of the device, and plays the role of transmitting ions, balancing charges and blocking electrons. It has an important impact on the safety and overall performance of reflective flexible electrochromic devices. Therefore, improving the material properties of the electrolyte layer is of great significance for optimizing the performance of reflective flexible electrochromic devices and promoting the development of electrochromic spectrum control technology.

[0004] Generally speaking, the ideal electrolyte in reflective flexible electrochromic devices should have excellent mechanical, chemical and thermal stability, be easy to prepare, low cost and be resistant to bending. Traditional liquid electrolytes have limitations such as easy leakage and difficult packaging during device preparation. Inorganic solid electrolytes have problems such as unstable contact interface with electrodes, low ionic conductivity, brittleness and high preparation cost. Therefore, the development of green and environmentally friendly electrolytes that are easy to prepare and have the advantages of both liquid and solid electrolytes has become the key to solving these problems. Hydrogel electrolytes are a quasi-solid electrolyte formed by cross-linking hydrophilic polymers and filling salt ion solutions in a porous structure. They have the advantages of high ionic conductivity, good interface compatibility, environmental friendliness and good flexibility and adaptability.

[0005] However, the existing electrochromic devices using hydrogel as electrolyte generally cross-link and solidify the hydrogel in the cavity of the device. During the curing process of the hydrogel, due to the gel effect, it is easy to cause uneven contact between the gel and the electrochromic layer, reduce compatibility, and cause color difference in the electrochromic device. To this end, in response to the problems raised in the above background technology, those skilled in the art have proposed a reflective flexible electrochromic device based on a hydrogel electrolyte, a preparation method and an application. Summary of the invention

[0006] The object of the present invention is to provide a reflective flexible electrochromic device based on a hydrogel electrolyte, a preparation method and an application thereof, so as to solve the problems raised in the above-mentioned background technology.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A reflective flexible electrochromic device based on a hydrogel electrolyte comprises a first conductive substrate and a second conductive substrate, wherein the first conductive substrate and the second conductive substrate are arranged opposite to each other;

[0009] A hydrogel electrolyte layer is laminated on one side of the first conductive substrate, and an electrochromic layer is laminated on one side of the second conductive substrate, wherein the hydrogel electrolyte layer and the electrochromic layer are laminated on each other;

[0010] A convex structure is formed on one side of the hydrogel electrolyte layer and the electrochromic layer that are bonded to each other. The convex structure is formed by a porous polystyrene template on the hydrogel electrolyte layer and the electrochromic layer.

[0011] Furthermore, the first conductive substrate and the second conductive substrate are both zinc foil metal conductive substrates, and the first conductive substrate and the second conductive substrate need to be pre-treated.

[0012] Furthermore, the steps of pre-treating the first conductive substrate and the second conductive substrate are:

[0013] The first conductive substrate and the second conductive substrate were first ultrasonically cleaned for 30 minutes with a 1:1 volume ratio of alcohol and acetone, then rinsed with sufficient deionized water, and finally dried with a hair dryer.

[0014] Furthermore, the method for preparing the porous polystyrene template comprises the following steps:

[0015] Polystyrene is dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, and the mixed solution is cast on a glass substrate. After the toluene evaporates naturally at a relative humidity of 20-40% and a temperature of 25-35°C, a porous polystyrene template is obtained, and the mass ratio of the sodium dodecyl sulfate, polystyrene and toluene is 1:(10-25):(400-600).

[0016] Furthermore, the method for preparing the hydrogel electrolyte layer having a protruding structure formed on the surface comprises the following steps:

[0017] S101, adding zinc chloride and acrylamide into deionized water, stirring and dissolving to obtain a mixed solution;

[0018] S102, adding N,N'-methylenebisacrylamide and ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 minutes, and introducing argon gas during the stirring process to obtain a hydrogel solution;

[0019] S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 1-5 h to obtain a hydrogel with the porous polystyrene template;

[0020] S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

[0021] Furthermore, the mass ratio of zinc chloride, acrylamide and deionized water in step S101 is 1:(4-8):(12-20), and the mass ratio of N,N'-methylenebisacrylamide and ammonium persulfate to acrylamide in step S101 in step S102 is 1:(8-14):(300-500).

[0022] Furthermore, the method for preparing the electrochromic layer having a protruding structure on the surface comprises the following steps:

[0023] S201, dissolving tungstic acid in 30% by mass hydrogen peroxide, stirring and mixing to obtain a mixed solution;

[0024] S202, continuing to add the mixed solution of propanol and deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 1-2, to obtain a tungsten oxide precursor solution;

[0025] S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 75-95° C. for 18-36 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

[0026] Furthermore, the mass ratio between the tungsten-free acid and the hydrogen peroxide in step S201 is 1:(15-30), and the mass ratio between the propanol and the deionized water in step S202 and the mass ratio between the tungstic acid in step S201 is (10-20):(20-35):1.

[0027] A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte, the preparation method comprising the following steps:

[0028] S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, evacuating the surface and leaving it to stand for 3-8 hours;

[0029] S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte;

[0030] Graphene is also ultrasonically dispersed in the polyethylene glycol solution in step S1, and the mass ratio of polyethylene glycol, deionized water and graphene in the polyethylene glycol solution is 1:20:0.2.

[0031] The above-mentioned reflective flexible electrochromic devices based on hydrogel electrolytes are used in the fields of smart windows, aerospace vehicles, automobile rearview mirrors, smart displays, information storage devices and sensors.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The hydrogel electrolyte layer and the electrochromic layer prepared in the present invention are both formed with a convex structure on one side through a polystyrene template. The size of the convex structure is at the micron level. The smaller convex structure greatly enhances the compatibility between the hydrogel electrolyte layer and the electrochromic layer, prevents uneven contact due to the gel effect, and reduces the color difference of the electrochromic device.

[0034] 2. In the present invention, the hydrogel electrolyte layer and the electrochromic layer are treated with a polyethylene glycol solution, which effectively wets the two layers and effectively improves the compatibility of the protruding structures on the surfaces of the two layers. The graphene contained in the polyethylene glycol solution improves the conductivity between the layers and facilitates ion migration. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The process flow chart of preparing a reflective flexible electrochromic device based on a hydrogel electrolyte according to the present invention;

[0036] Figure 2 This is a process flow chart for preparing a hydrogel electrolyte layer having a protrusion-like structure formed on the surface in the present invention;

[0037] Figure 3 A process flow chart for preparing an electrochromic layer having a protruding structure on the surface in the present invention

[0038] Figure 4 Spectra of the electrochromic layer with protrusion-shaped structures formed on the surface in Example 1 of the present invention in different states in the visible light band;

[0039] Figure 5 Spectra of the reflective flexible electrochromic device based on hydrogel electrolyte prepared in Example 1 of the present invention at different voltages;

[0040] Figure 6 This is a graph of the emission power of the reflective flexible electrochromic device based on the hydrogel electrolyte prepared in Example 1 of the present invention at different voltages in the infrared band;

[0041] Figure 7 This is a comparison chart of the emissivity of the reflective flexible electrochromic device based on hydrogel electrolyte prepared in Example 1 of the present invention at different voltages and different infrared bands. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] See also Figures 1 to 7 , the present invention provides:

[0044] Example 1

[0045] A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte comprises the following steps:

[0046] S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, evacuating the surface and leaving it to stand for 6 hours;

[0047] S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte;

[0048] A convex structure is formed on one side where the hydrogel electrolyte layer and the electrochromic layer are bonded to each other, and the convex structure is formed by a porous polystyrene template on both the hydrogel electrolyte layer and the electrochromic layer;

[0049] The method for preparing the porous polystyrene template comprises the following steps:

[0050] 10.2 g of polystyrene was dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, the amount of sodium dodecyl sulfate used was 0.51 g, and the amount of toluene used was 250 g. The mixed solution was cast on a glass substrate, and at a relative humidity of 30% and a temperature of 30° C., after the toluene was naturally evaporated, a porous polystyrene template was obtained;

[0051] The method for preparing the hydrogel electrolyte layer having a protruding structure formed on the surface comprises the following steps:

[0052] S101, adding 0.7 g of zinc chloride and 4.2 g of acrylamide to 11.2 g of deionized water, stirring and dissolving to obtain a mixed solution;

[0053] S102, adding 0.011 g of N,N'-methylenebisacrylamide and 0.12 g of ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 min, and introducing argon gas during the stirring process to obtain a hydrogel solution;

[0054] S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 4 h to obtain a hydrogel with the porous polystyrene template;

[0055] S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

[0056] The method for preparing the electrochromic layer having a protruding structure on the surface comprises the following steps:

[0057] S201, dissolving 2.4 g of tungstic acid into 58 g of 30% by mass hydrogen peroxide, stirring and mixing to obtain a mixed solution;

[0058] S202, adding 36 g of propanol and 72 g of deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 1 to obtain a tungsten oxide precursor solution;

[0059] S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 90° C. for 25 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

[0060] Example 2

[0061] A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte comprises the following steps:

[0062] S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, evacuating the surface and leaving it to stand for 3 hours;

[0063] S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte;

[0064] A convex structure is formed on one side where the hydrogel electrolyte layer and the electrochromic layer are bonded to each other, and the convex structure is formed on the hydrogel electrolyte layer and the electrochromic layer through a porous polystyrene template;

[0065] The method for preparing the porous polystyrene template comprises the following steps:

[0066] 10.2 g of polystyrene was dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, the amount of sodium dodecyl sulfate used was 1.02 g, and the amount of toluene used was 408 g. The mixed solution was cast on a glass substrate, and at a relative humidity of 20% and a temperature of 25° C., after the toluene was naturally evaporated, a porous polystyrene template was obtained;

[0067] The method for preparing the hydrogel electrolyte layer having a protruding structure formed on the surface comprises the following steps:

[0068] S101, adding 1.05 g of zinc chloride and 4.2 g of acrylamide to 12.6 g of deionized water, stirring and dissolving to obtain a mixed solution;

[0069] S102, adding 0.014 g of N,N'-methylenebisacrylamide and 0.112 g of ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 min, and introducing argon gas during the stirring process to obtain a hydrogel solution;

[0070] S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 1 h to obtain a hydrogel with the porous polystyrene template;

[0071] S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

[0072] The method for preparing the electrochromic layer having a protruding structure on the surface comprises the following steps:

[0073] S201, dissolving 2.4 g of tungstic acid into 36 g of 30% by mass hydrogen peroxide, stirring and mixing to obtain a mixed solution;

[0074] S202, adding 24 g of propanol and 48 g of deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 1 to obtain a tungsten oxide precursor solution;

[0075] S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 75° C. for 18 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

[0076] Example 3

[0077] A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte comprises the following steps:

[0078] S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, evacuating the surface and leaving it to stand for 8 hours;

[0079] S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte;

[0080] A convex structure is formed on one side where the hydrogel electrolyte layer and the electrochromic layer are bonded to each other, and the convex structure is formed on the hydrogel electrolyte layer and the electrochromic layer through a porous polystyrene template;

[0081] The method for preparing the porous polystyrene template comprises the following steps:

[0082] 10.2 g of polystyrene was dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, the amount of sodium dodecyl sulfate used was 0.408 g, and the amount of toluene used was 244.8 g. The mixed solution was cast on a glass substrate, and at a relative humidity of 40% and a temperature of 35° C., after the toluene was naturally evaporated, a porous polystyrene template was obtained;

[0083] The method for preparing the hydrogel electrolyte layer having a protruding structure formed on the surface comprises the following steps:

[0084] S101, adding 0.525 g of zinc chloride and 4.2 g of acrylamide to 10.5 g of deionized water, stirring and dissolving to obtain a mixed solution;

[0085] S102, adding 0.0084 g of N,N'-methylenebisacrylamide and 0.117 g of ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 min, and introducing argon gas during the stirring process to obtain a hydrogel solution;

[0086] S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 5 h to obtain a hydrogel with the porous polystyrene template;

[0087] S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

[0088] The method for preparing the electrochromic layer having a protruding structure on the surface comprises the following steps:

[0089] S201, dissolving 2.4 g of tungstic acid into 72 g of 30% by mass hydrogen peroxide, stirring and mixing to obtain a mixed solution;

[0090] S202, adding 48 g of propanol and 84 g of deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 2 to obtain a tungsten oxide precursor solution;

[0091] S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 95° C. for 36 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

[0092] Example 4

[0093] A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte comprises the following steps:

[0094] S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, evacuating the surface and leaving it to stand for 7 hours;

[0095] S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte;

[0096] A convex structure is formed on one side where the hydrogel electrolyte layer and the electrochromic layer are bonded to each other, and the convex structure is formed on the hydrogel electrolyte layer and the electrochromic layer through a porous polystyrene template;

[0097] The method for preparing the porous polystyrene template comprises the following steps:

[0098] 10.2 g of polystyrene was dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, the amount of sodium dodecyl sulfate used was 0.56 g, and the amount of toluene used was 250 g. The mixed solution was cast on a glass substrate, and at a relative humidity of 35% and a temperature of 25° C., after the toluene was naturally evaporated, a porous polystyrene template was obtained;

[0099] The method for preparing the hydrogel electrolyte layer having a protruding structure formed on the surface comprises the following steps:

[0100] S101, adding 0.65 g zinc chloride and 4.2 g acrylamide into 11.7 g deionized water, stirring and dissolving to obtain a mixed solution;

[0101] S102, adding 0.013 g of N,N'-methylenebisacrylamide and 0.14 g of ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 min, and introducing argon gas during the stirring process to obtain a hydrogel solution;

[0102] S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 1-5 h to obtain a hydrogel with the porous polystyrene template;

[0103] S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

[0104] The method for preparing the electrochromic layer having a protruding structure on the surface comprises the following steps:

[0105] S201, dissolving 2.4g of tungstic acid into 52g of 30% hydrogen peroxide, stirring and mixing to obtain a mixed solution; the mass ratio of tungstic acid to hydrogen peroxide in step S201 is 1:(15-30)

[0106] S202, adding 28 g of propanol and 65 g of deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 1.5 to obtain a tungsten oxide precursor solution;

[0107] S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 85° C. for 30 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

[0108] The polyethylene glycol solution used in step S1 of the above embodiment 1-4 also contains graphene dispersed by ultrasonication, and the mass ratio of polyethylene glycol, deionized water and graphene in the polyethylene glycol solution is 1:20:0.2;

[0109] The degree of polymerization of the polystyrene selected in the above embodiments is 50-100.

[0110] Comparative Example 1

[0111] The difference between Comparative Example 1 and Example 1 is that step S103 and step S104 are omitted, and the curing of the hydrogel electrolyte layer is directly completed on a smooth glass substrate instead. The surface of the obtained hydrogel electrolyte layer is smooth, and the remaining steps are exactly the same as those in Example 1.

[0112] Comparative Example 2

[0113] The difference between Comparative Example 2 and Example 1 is that step S203 is omitted, and the electrochromic layer is directly formed on a smooth glass substrate instead. The surface of the formed electrochromic layer is smooth, and the remaining steps are exactly the same as those of Example 1.

[0114] Comparative Example 3

[0115] The difference between Comparative Example 3 and Example 1 is that step S1 is partially omitted, thereby eliminating the addition of polyethylene glycol solution, and the remaining steps are exactly the same as those of Example 1.

[0116] Comparative Example 4

[0117] The difference between Comparative Example 4 and Comparative Example 1 is that step S203 is omitted, and the electrochromic layer is directly formed on a smooth glass substrate instead. The surfaces of the formed electrochromic layer and the hydrogel electrolyte layer are both smooth, and the remaining steps are exactly the same as those of Comparative Example 1.

[0118] Comparative Example 5

[0119] The difference between Comparative Example 5 and Example 1 is that the first conductive substrate, the electrochromic layer and the second conductive substrate are first assembled together, and a cavity is formed between the first conductive substrate and the electrochromic layer. The electrochromic layer is prepared in the same manner as the electrochromic layer in Comparative Example 2. Then, the hydrogel solution prepared in Example 1 is poured into the cavity, and the hydrogel solution is cured by ultraviolet rays in the cavity.

[0120] 9 groups of reflective flexible electrochromic devices based on hydrogel electrolytes were prepared by the above Examples 1-4 and Comparative Examples 1-5, and a point was selected at the center of the 8 groups of reflective flexible electrochromic devices based on hydrogel electrolytes, and marked as E a , select four points on the edge and record them as E1, E2, E3, and E4 respectively. The four points on the edge are at the same distance from the center point, and the ring formed by the four points on the edge divides the ring into two halves;

[0121] 9 groups of reflective flexible electrochromic devices based on hydrogel electrolyte were connected to power supply. When the edge positions E1, E2, E3, and E4 changed from fading state to colored state, the power supply was immediately turned off. The edge positions E1, E2, E3, and E4 and the center position E1 were tested by colorimeter. a The color difference ΔE of the four edge positions and the center point is recorded as ΔE a1 , ΔE a2 , ΔE a3 , ΔE a4 , the test results are shown in Table 1:

[0122] Table 1: Color difference display table of 9 groups of reflective flexible electrochromic devices based on hydrogel electrolyte prepared in Examples 1-4 and Comparative Examples 1-5

[0123]

[0124]

[0125] It can be seen from the data of Example 1 and Comparative Examples 4-5 in Table 1 above that the present invention can effectively reduce the surface color difference of the electrochromic device by forming a protruding structure on the surface of the hydrogel electrolyte layer and the electrochromic layer. The color difference of the electrochromic device in Comparative Examples 1-2 is greater than that in Comparative Examples 4-5. Since only one side of the hydrogel electrolyte layer and the electrochromic layer has protrusions, the contact may be more uneven, which in turn increases the color difference. By comparing the data of Comparative Example 3 with that of Example 1, it can be seen that by coating the polyethylene glycol solution on the contact surface of the hydrogel electrolyte layer and the electrochromic layer, the compatibility between the two is further improved, the uniformity of ion conduction is improved, and the color difference is reduced.

[0126] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A reflective flexible electrochromic device based on a hydrogel electrolyte, characterized in that: It comprises a first conductive substrate and a second conductive substrate, wherein the first conductive substrate and the second conductive substrate are arranged opposite to each other; A hydrogel electrolyte layer is laminated on one side of the first conductive substrate, and an electrochromic layer is laminated on one side of the second conductive substrate, wherein the hydrogel electrolyte layer and the electrochromic layer are laminated on each other; A convex structure is formed on one side of the hydrogel electrolyte layer and the electrochromic layer that are bonded to each other. The convex structure is formed by a porous polystyrene template on the hydrogel electrolyte layer and the electrochromic layer.

2. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 1, characterized in that: The first conductive substrate and the second conductive substrate are both zinc foil metal conductive substrates, and the first conductive substrate and the second conductive substrate need to be pre-treated.

3. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 2, characterized in that: The steps of pre-treating the first conductive substrate and the second conductive substrate are: The first conductive substrate and the second conductive substrate were first ultrasonically cleaned for 30 minutes with a 1:1 volume ratio of alcohol and acetone, then rinsed with sufficient deionized water, and finally dried with a hair dryer.

4. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 1, characterized in that: The preparation method of the porous polystyrene template comprises the following steps: Polystyrene is dissolved in toluene containing sodium dodecyl sulfate to form a mixed solution, and the mixed solution is cast on a glass substrate. After the toluene evaporates naturally at a relative humidity of 20-40% and a temperature of 25-35°C, a porous polystyrene template is obtained, and the mass ratio of the sodium dodecyl sulfate, polystyrene and toluene is 1:(10-25):(400-600).

5. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 4, characterized in that: The method for preparing the hydrogel electrolyte layer having a convex structure formed on the surface comprises the following steps: S101, adding zinc chloride and acrylamide into deionized water, stirring and dissolving to obtain a mixed solution; S102, adding N,N'-methylenebisacrylamide and ammonium persulfate to the mixed solution obtained in step S101, stirring continuously for 60 minutes, and introducing argon gas during the stirring process to obtain a hydrogel solution; S103, coating the hydrogel solution obtained in step S102 on the surface of the porous polystyrene template, and irradiating the porous polystyrene template with ultraviolet light of a wavelength of 350 nm for 1-5 h to obtain a hydrogel with the porous polystyrene template; S104, dissolving and removing the template of the hydrogel with the porous polystyrene template obtained in step S103 by toluene, to obtain a hydrogel electrolyte layer with a protruding structure formed on the surface.

6. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 5, characterized in that: The mass ratio of zinc chloride, acrylamide and deionized water in step S101 is 1:(4-8):(12-20), and the mass ratio of N,N'-methylenebisacrylamide and ammonium persulfate to acrylamide in step S102 is 1:(8-14):(300-500).

7. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 4, characterized in that: The method for preparing the electrochromic layer having a protrusion-shaped structure formed on the surface comprises the following steps: S201, dissolving tungstic acid in 30% by mass hydrogen peroxide, stirring and mixing to obtain a mixed solution; S202, continuing to add the mixed solution of propanol and deionized water to the mixed solution obtained in step S201, and then dropping 2 mol / L hydrochloric acid to adjust the pH to 1-2, to obtain a tungsten oxide precursor solution; S203, coating the tungsten oxide precursor solution obtained in step S202 on a porous polystyrene template, reacting at 75-95° C. for 18-36 hours to obtain a porous polyethylene template with a tungsten oxide film, dissolving the polystyrene template with toluene to obtain an electrochromic layer with a protruding structure formed on the surface.

8. The reflective flexible electrochromic device based on hydrogel electrolyte according to claim 7, characterized in that: The mass ratio between the non-tungstic acid and the hydrogen peroxide in step S201 is 1:(15-30), and the mass ratio between the propanol and the deionized water in step S202 and the mass ratio between the tungstic acid in step S201 is (10-20):(20-35):

1.

9. A method for preparing a reflective flexible electrochromic device based on a hydrogel electrolyte as claimed in any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1, coating the surface of the electrochromic layer and the hydrogel electrolyte layer in contact with each other with a polyethylene glycol solution, and after the electrochromic layer and the hydrogel electrolyte layer are attached to each other, vacuuming and leaving them to stand for 3-8 hours; S2, assembling the first conductive substrate, the hydrogel electrolyte layer, the electrochromic layer and the second conductive substrate in sequence, and sealing them with a sealing glue to obtain a reflective flexible electrochromic device based on a hydrogel electrolyte; Graphene is also ultrasonically dispersed in the polyethylene glycol solution in step S1, and the mass ratio of polyethylene glycol, deionized water and graphene in the polyethylene glycol solution is 1:20:0.

2.

10. Application of the reflective flexible electrochromic device based on hydrogel electrolyte as claimed in any one of claims 1 to 8 in the fields of smart windows, aerospace vehicles, automobile rearview mirrors, smart displays, information storage devices and sensors.

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