An electrochromic device based on ammonium ion aqueous electrolyte and a preparation method and application thereof

Abstract

The application aims to provide an electrochromic device based on ammonium ion aqueous electrolyte and a preparation method and application thereof, and belongs to the technical field of electrochromic devices.The electrochromic device is composed of a transparent conductive glass substrate layer, an ion storage layer, a hydrogel ion electrolyte layer, an electrochromic layer and a top transparent conductive layer from bottom to top.The electrochromic device electrolyte layer based on ammonium ions adopts a hydrogel ion electrolyte, which can effectively promote the ammonium ion migration process and improve the long cycle stability of the ammonium ion electrochromic device.The electrochromic device based on ammonium ions has a wide application prospect in the fields of intelligent systems, intelligent windows and intelligent electronic products.

Description

Technical Field

[0001] This invention belongs to the field of electrochromic device technology, specifically relating to an electrochromic device based on an ammonium ion aqueous electrolyte, its preparation method, and its application. Background Technology

[0002] Electrochromism refers to a stable and reversible change in the appearance properties of a material or device under the influence of an applied electric field, which is mainly reflected in visual changes in transmittance or color.

[0003] Electrochromic devices, due to their ability to change color in response to external stimuli, exhibit significant advantages in specific applications. Currently, this technology is widely used in various fields, including smart glass, aircraft, automotive rearview mirrors, smart screens, data storage devices, and sensing technologies.

[0004] Electrochromic devices and supercapacitors share similarities in electrode materials, structural design, and reaction kinetics, and are sometimes referred to as "rocking chair" batteries. Based on these similarities, electrochromic technology can be combined with supercapacitors to develop energy storage devices with electrochromic properties. Users can visually assess the operating status of these devices by observing color changes, thereby reducing irreversible damage to device performance caused by external factors. These unique advantages indicate that electrochromic energy storage devices have enormous application potential in the field of smart electronic devices.

[0005] Current electrochromic energy storage devices typically consist of five layers: a bottom transparent electrode, an ion storage layer, an ion electrolyte layer, an electrochromic layer, and a top transparent electrode, forming a composite device integrating optoelectronic functions. When a specific voltage difference is applied across the device, ions and electrons migrate inside and outside the device, giving it the ability to change color and store energy.

[0006] Existing electrochromic materials or devices based on aqueous electrolytes (such as lithium, zinc, calcium, and aluminum) have poor cycle stability and small modulation amplitude.

[0007] NH4 + It has advantages such as abundant resources, wide availability, eco-friendliness, small hydrated ion radius, light molar mass, fast diffusion rate, and good cycle performance.

[0008] In recent years, due to the non-metallic ammonium ion (NH4+) + Due to their light molar mass, low cost, and environmental friendliness, ammonium ion electrochromic devices (AECDs) have attracted great interest in smart energy storage systems. However, developing an electrochromic device with both significant electrochromic performance and excellent long-term cycle stability in a suitable electrolyte is a formidable challenge. Therefore, the development of an ammonium ion electrochromic energy storage device is of great significance. Summary of the Invention

[0009] The purpose of this invention is to provide an electrochromic device based on an ammonium ion aqueous electrolyte, its preparation method and application, which has both significant electrochromic performance and excellent long-term cycling stability.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] An electrochromic device based on an ammonium ion aqueous electrolyte comprises, from bottom to top, a transparent conductive glass substrate, an ion storage layer, a hydrogel ion electrolyte layer, an electrochromic layer, and a top transparent conductive layer; the hydrogel ion electrolyte layer is prepared by soaking hydrogel in a 0.25M (NH4)2SO4 solution for 5 hours.

[0012] Furthermore, the conductive material coated on the transparent conductive glass substrate includes an FTO film or an ITO film; the top transparent conductive layer material is an ITO thin film.

[0013] Furthermore, the ion storage layer material includes a Prussian blue (PB) nanosheet film.

[0014] Furthermore, the area of ​​the hydrogel ionoelectrolyte layer is 2 × 2 cm. 2 The thickness is 2mm.

[0015] Furthermore, the electrochromic layer material is Nb. 18 W 16 O 93 film.

[0016] A method for preparing an electrochromic device based on an ammonium ion aqueous electrolyte includes the following steps:

[0017] S1. Clean the transparent conductive glass substrate with a mixture of ether and ethanol in a volume ratio of 1:1 for 10 minutes using ultrasonic cleaning, and finally dry it with a hair dryer for later use.

[0018] S2. Weigh 0.54g ferric chloride hexahydrate, 0.66g potassium ferricyanide, and 1.5g potassium chloride, add them to 200mL of deionized water, stir for 15min until completely dissolved, then add 0.1mL concentrated sulfuric acid to adjust the pH to an acidic environment, stir thoroughly to obtain PB precipitate.

[0019] Electrochemical deposition was performed on a transparent conductive glass substrate in PB deposition solution to obtain a transparent conductive glass substrate with PB thin film electrode deposited on it. After washing with deionized water, the substrate was heat-treated in a 60℃ constant temperature oven for 10 min.

[0020] S3. Weigh 6g of acrylamide and dissolve it in 18mL of deionized water to obtain a mixed solution. Weigh 0.012g of methylenebisacrylamide and 0.12g of ammonium persulfate and add them to the above mixed solution and stir thoroughly until completely dissolved. Then, purge with pure argon gas for 5 minutes and slowly inject it into the mold with a syringe, taking care not to generate air bubbles. Seal the mold with plastic wrap and keep it in a constant temperature oven at 60℃ for 3 hours to obtain a hydrogel. Take an appropriate size of the hydrogel and immerse it in 0.25M (NH4)2SO4 solution for 5 hours to obtain the hydrogel ion electrolyte layer.

[0021] S4. Mix 2 mL of deionized water with 8 mL of ethanol and stir thoroughly. Add 0.2 g of niobium oxalate hydrate and stir for 0.5 h. Add 0.49 g of ammonium metatungstate hydrate and stir for 0.5 h. Add 1.0 g of citric acid hydrate and heat in a water bath at 60 °C for 5 min to obtain Nb. 18 W 16 O 93 Precursor fluid;

[0022] Nb was spin-coated onto ITO transparent conductive glass using a spin coating method. 18 W 16 O 93 After the precursor liquid is applied, it is placed in a tube furnace for heat treatment at a temperature of 600℃ for 2 hours to obtain a top transparent conductive layer with an electrochromic layer spin-coated.

[0023] S5. The transparent conductive glass substrate with PB thin film electrode deposited, the hydrogel ion electrolyte layer and the top transparent conductive layer are sequentially bonded from bottom to top, and a layer of sealant is applied around the perimeter to prepare an electrochromic device based on ammonium ion aqueous electrolyte.

[0024] Application of an electrochromic device based on ammonium ion aqueous electrolyte in the fabrication of intelligent systems, intelligent windows and intelligent electronic products.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention utilizes a hydrogel ionic electrolyte in the electrolyte layer of an ammonium ion electrochromic device, which effectively promotes the migration process of ammonium ions. The prepared ammonium ion electrochromic device exhibits excellent long-term cycling stability, retaining 99.79% of its capacity after 1000 cycles.

[0027] 2. The ammonium ion electrochromic device constructed in this invention has an ultra-thin all-inorganic structure, which not only has excellent cycle stability performance, but also a wide optical modulation amplitude, with an optical modulation amplitude of about 61.1% at 630nm.

[0028] 3. This invention uses a combination of electrochemical deposition and spin coating to prepare ammonium ion-based electrochromic devices, which has the advantages of being green and energy-saving and having a high degree of process control. Attached Figure Description

[0029] Figure 1 This is the electrochromic long-cycle performance test curve of the PB thin film electrode.

[0030] Figure 2 It is Nb 18 W 16 O 93 Electrochromic long-cycle performance test curves of thin-film electrodes.

[0031] Figure 3 This is a schematic diagram of the transmittance of the fading state of the ammonium ion electrochromic device under different voltages in Example 1.

[0032] Figure 4 This is a schematic diagram of the CV curve changes at different scan rates based on the ammonium ion electrochromic device in Example 1.

[0033] Figure 5 Example 1 shows the charge-discharge performance GCD curve of an ammonium ion electrochromic device.

[0034] Figure 6 Example 1 shows the GCD curves of an ammonium ion electrochromic device in single, series, and parallel configurations.

[0035] Figure 7 This is the optical memory curve of Example 1 based on the long-cycle cyclic voltammetry test of the ammonium ion electrochromic device.

[0036] Figure 8 This is a schematic diagram of the long-cycle coulombic efficiency and capacity retention of an ammonium ion electrochromic device in Example 1.

[0037] Figure 9 The example is the optical memory curve based on an ammonium ion electrochromic device.

[0038] Figure 10 This is a comparison of the capacity retention of PB thin-film electrodes with ion storage layers in three anionic electrolytes over long cycles.

[0039] Figure 11 This is a comparison of the areal capacitance of the PB thin-film electrode in different cationic electrolytes.

[0040] Figure 12 The CV curves of the PB thin-film electrode for ion storage layer in (NH4)2SO4 solutions of different concentrations are shown.

[0041] Figure 13The capacity retention curves of the PB thin-film electrode for ion storage layer after 1000 cycles in 0.05M, 0.25M, 1M, and 4M (NH4)2SO4 solutions. Detailed Implementation

[0042] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention, so that those skilled in the art can better understand and utilize the present invention, and are not intended to limit the scope of protection of the present invention.

[0043] Unless otherwise specified, the production processes, experimental methods, or testing methods involved in the embodiments of this invention are all conventional methods in the prior art, and their names and / or abbreviations are all conventional names in the field, which are very clear and distinct in the relevant application areas. Those skilled in the art can understand the conventional process steps based on the names and apply the corresponding equipment to implement them according to conventional conditions or conditions recommended by the manufacturer.

[0044] The various instruments, equipment, raw materials or reagents used in the embodiments of this invention are not subject to any special restrictions on their source. They are all conventional products that can be purchased through regular commercial channels and can be prepared according to conventional methods known to those skilled in the art.

[0045] The various ammonium ion-based electrochromic devices provided in the following embodiments of the present invention are specifically prepared according to the methods described below.

[0046] The required ITO transparent conductive glass substrate is ultrasonically cleaned for 10 minutes with a 1:1 mixture of ether and ethanol, and then dried with a hair dryer for later use.

[0047] Weigh 0.54g ferric chloride hexahydrate, 0.66g potassium ferricyanide, and 1.5g potassium chloride, add them to 200mL of deionized water, stir for 15min until completely dissolved, then add 0.1mL concentrated sulfuric acid to adjust the pH to an acidic environment, and stir thoroughly to obtain PB precipitate.

[0048] The PB thin film electrode for depositing the ion storage layer was obtained by using a dual-electrode constant current polarization system electrochemical workstation with ITO glass as the working electrode and a platinum electrode as the counter electrode. Electrochemical deposition was carried out on ITO transparent conductive glass in PB deposition solution. Deposition was performed for 300 s at a polarization current of -0.16 mA to obtain the PB thin film electrode deposited on ITO transparent conductive glass.

[0049] The ITO transparent conductive glass with PB thin film electrode deposited was slowly placed into a beaker containing deionized water until it was completely submerged, and the deposited liquid on the PB film was washed off twice.

[0050] The washed ITO transparent conductive glass with PB thin film electrode deposited was placed in a 60℃ constant temperature oven for heat treatment. The heat treatment of the PB thin film electrode of the ion storage layer was completed after 10 minutes.

[0051] The PB thin film electrode obtained by the above heat treatment exhibits excellent electrochromic and energy storage performance. Figure 1 The corresponding test curves are given. It can be seen that during the electrochemical reaction of cyclic voltammetry, the optical transmittance of the PB thin film electrode repeatedly and reversibly changes within the range of 16.2% (colored state) to 79.6% (bleached state), and the optical modulation amplitude can reach 63.2%. After 5000 consecutive coloring-bleaching cycles, the transmittance modulation amplitude of the PB electrode still maintains the initial value of 82.02%, indicating that the PB thin film electrode has stable and reversible electrochromic properties during the electrochemical reaction.

[0052] The hydrogel ion electrolyte layer was prepared by immersing the hydrogel in a 0.25 M (NH4)2SO4 solution for 5 hours.

[0053] The specific preparation process for the hydrogel ion electrolyte layer is as follows: 6g of acrylamide is dissolved in 18mL of deionized water. 0.012g of methylenebisacrylamide and 0.12g of ammonium persulfate are added to the above mixture and stirred thoroughly until completely dissolved. Then, pure argon gas is passed through for 5 minutes, and the mixture is slowly injected into the mold using a syringe (avoiding air bubbles). After sealing with plastic wrap, the mixture is kept in a constant temperature oven at 60℃ for 3 hours to obtain the hydrogel. A suitable size of the hydrogel is then immersed in 0.25 M (NH4)2SO4 solution for 5 hours to obtain the hydrogel ion electrolyte layer.

[0054] Electrochromic layer Nb 18 W 16 O 93 The thin film was prepared by spin coating and heat treatment in a tube furnace to prepare Nb. 18 W 16 O 93 The precursor solution was prepared by mixing 2 mL of deionized water with 8 mL of ethanol and stirring thoroughly, adding 0.2 g of niobium oxalate hydrate and stirring for 0.5 h, adding 0.49 g of ammonium metatungstate hydrate and stirring for 0.5 h, adding 1.0 g of citric acid hydrate and heating in a water bath at 60 °C for 5 min.

[0055] Place the cleaned ITO transparent conductive glass on a spin coater (conductive side up), and use a pipette to evenly drop the precursor solution onto the ITO transparent conductive glass. The spin coating parameters are: low speed 300 rpm, high speed 2500 rpm, low speed duration 20s, high speed duration 40s, and spin coat twice.

[0056] Spin-coated with Nb 18W 16 O 93 The ITO transparent conductive glass of the precursor liquid was placed in a tube furnace for heat treatment at a temperature of 600℃ for 2 hours.

[0057] The specific temperature control is as follows: At room temperature, the temperature is increased to 180℃ after 0.5 hours; held at 180℃ for 0.5 hours; then increased to 250℃ after another 0.5 hours; held at 250℃ for 0.5 hours; then increased to 400℃ after another 0.5 hours; held at 400℃ for 0.5 hours; then increased to 600℃ after 1 hour; held at 600℃ for 2 hours; then decreased to 100℃ after another 2 hours; and finally cooled to room temperature to complete the Nb treatment. 18 W 16 O 93 Heat treatment of thin films.

[0058] The Nb obtained by the above heat treatment 18 W 16 O 93 Thin-film electrodes exhibit excellent electrochromic properties. Figure 2 The corresponding test curves are given, and it can be seen that Nb 18 W 16 O 93 During the electrochemical reaction of cyclic voltammetry, the optical transmittance of the thin-film electrode repeatedly and reversibly changes within the range of 29.7% (colored state) to 61.4% (bleached state), with an optical modulation amplitude reaching 31.7%. After 1000 consecutive coloring-bleaching cycles, Nb 18 W 16 O 93 The transmittance modulation amplitude of the thin-film electrode remained at 87.07% of its initial value, indicating that Nb 18 W 16 O 93 Thin-film electrodes exhibit stable and reversible electrochromic properties during electrochemical reactions.

[0059] Following the above preparation process, an ion storage layer with PB deposited on transparent conductive ITO glass, a hydrogel ion electrolyte layer, and a top transparent conductive layer with an electrochromic layer spin-coated are sequentially bonded together from bottom to top. A layer of sealant is then applied around the device to prepare an ammonium ion-based electrochromic device.

[0060] The prepared ammonium ion electrochromic energy storage device was attached with copper tape to both ends of the bottom and top transparent conductive layers to bring out positive and negative test electrodes. The device was attached to a test frame and placed in a UV-Vis spectrophotometer. The positive and negative test electrodes brought out by the device were connected to an electrochemical workstation for in-situ testing and characterization.

[0061] Example 1

[0062] The device structure of the ammonium ion electrochromic device prepared in this embodiment includes, from bottom to top: ITO transparent conductive glass; PB thin film layer; hydrogel ion electrolyte layer (5h), 2mm thick; Nb 18 W 16 O 93 Thin film layer; ITO transparent conductive layer.

[0063] The electrochromic and electrochemical performance of the ammonium ion-based electrochromic device was tested in situ using an electrochemical workstation and a UV-Vis spectrophotometer.

[0064] from Figure 3 The schematic diagram of the full-spectrum transmittance of the ammonium ion-based electrochromic device shows that the spectral transmittance of the electrochromic device gradually changes in the visible light range. As the voltage gradually increases, the device becomes increasingly colored, accompanied by a gradual decrease in its transmittance in the visible light range. Under different voltages, the transmittance of the device in the visible light range exhibits a large modulation amplitude. For example, during the process of the device transitioning from the faded state to the 1.7V colored state, its optical modulation amplitude at 630nm reaches approximately 51.1%.

[0065] Figure 4 This is a schematic diagram showing the changes of an ammonium ion electrochromic device under cyclic voltammetry testing with different scan rates. As the scan rate increases, the envelope area of ​​the CV curve gradually increases while maintaining a consistent rectangular shape, indicating that the ammonium ion electrochromic device is reversible during rapid charge and discharge.

[0066] Figure 5 Parametric curves for testing the charge-discharge behavior of an ammonium-ion electrochromic device are presented. Specifically, the fabricated device was connected to an electrochemical workstation, and charge-discharge tests were performed using a chronopotential method. Charge-discharge curves at different current densities were measured. It can be seen that the charge-discharge curves at different current densities exhibit good symmetry, indicating that the electrochemical polarization of the device electrodes is very small. The slopes of the charge-discharge curves at different current densities are non-linear, indicating the coexistence of pseudo-capacitor and battery-type charge storage characteristics.

[0067] Figure 6 To adopt Figure 5 The parameters shown were used to test the charge-discharge curves of the prepared ammonium ion-based electrochromic device in single, series, and parallel configurations. It can be seen that the output voltage of the series-connected ammonium ion-based electrochromic device doubles, while the charge-discharge time is equal; whereas the parallel-connected ammonium ion-based electrochromic device maintains a stable voltage, but the charge-discharge time doubles. The charge-discharge curves of the devices in series and parallel configurations are basically consistent with the charge-discharge curves of a single device; combined with... Figure 6As shown in the diagrams of series and parallel connections, the envelope areas of the charge-discharge curves are consistent in both series and parallel states. These results indicate that the fabricated ammonium ion-based electrochromic device exhibits good uniformity.

[0068] To further investigate the performance of ammonium ion-based electrochromic devices, the optical memory effect of the aforementioned fabricated devices under cyclic voltammetry was tested. Figure 3 This indicates that device voltage can affect its transmittance. Therefore, voltage changes during cyclic voltammetry testing will cause corresponding changes in the device's optical transmittance, and its electrochemical performance can be reflected by testing the device's optical memory effect.

[0069] Figure 7 Optical memory curves of an ammonium ion electrochromic device under cyclic voltammetry are presented. The initial modulation amplitude of the device was 61.1%, and after 1000 cycles, 97.4% of the modulation amplitude was still maintained, further demonstrating that the device has good cyclic stability.

[0070] Figure 8 The coulombic efficiency and capacitance retention curves of the ammonium ion electrochromic device under cyclic voltammetry are presented. At 0.4 mA / cm², -2 At the specified current density, the prepared ammonium-ion electrochromic energy storage device retained 99.79% of its capacity after 1000 cycles and still maintained 80.14% of its initial capacity after 3000 cycles, with a coulombic efficiency close to 100%, indicating that the prepared device has excellent electrochemical performance. The illustration shows the series-connected devices successfully lighting a red LED, highlighting its scalable integration performance in the field of smart electronics.

[0071] Compare with Example 1

[0072] The device structure of the ammonium ion electrochromic device prepared in this comparative example includes, from bottom to top: ITO transparent conductive glass; PB thin film layer; hydrogel ion electrolyte layer (4h), 2mm thick; Nb 18 W 16 O 93 Thin film layer; ITO transparent conductive layer.

[0073] The electrochromic device in this comparative example is exactly the same as that in Example 1, except that the hydrogel ion electrolyte layer is immersed in 0.25M (NH4)2SO4 solution for 4 hours.

[0074] Figure 7 and Figure 9 A comparison diagram of the optical memory effect of the electrochromic device prepared in Example 1 and the control example is provided.

[0075] Figure 7Optical memory curves of an ammonium ion-based electrochromic device immersed in 0.25M (NH4)2SO4 solution for 5 hours are presented under cyclic voltammetry testing. The device initially exhibited a transmittance of 61.1%, and after 1000 cycles, it still maintained 97.4% transmittance, further demonstrating the device's good cyclic stability.

[0076] Figure 9 The optical memory curves of an ammonium ion-based electrochromic device, which was immersed in 0.25M (NH4)2SO4 solution for 4 hours using a hydrogel electrolyte, were obtained under cyclic voltammetry. The initial modulation amplitude at 630 nm was 56.8%, and after 500 cycles, 68.8% of the modulation amplitude was retained. The comparison of the optical memory effects of the two devices further demonstrates that the device in Example 1 has better electrochemical performance.

[0077] Compare with Example 2

[0078] To further investigate the development of electrodes with both significant electrochromic properties and excellent long-cycle stability in suitable electrolytes, this comparative example aims to study the electrochemical performance of the ion storage layer PB electrode in different anionic electrolytes.

[0079] The method used in this comparative example to prepare the PB thin film electrode is consistent with the method described above for preparing the PB thin film electrode based on the ammonium ion electrochromic device.

[0080] In this comparative experiment, a 0.25M (NH4)2SO4 solution was used as a reference. To maintain the consistency of ammonium ion concentration, the concentrations of NH4Cl and NH4AC solutions were 0.5M.

[0081] Figure 10 The graph shows a comparison of the capacity retention of the PB thin-film electrode in three anionic electrolytes over long cycles. It can be seen that after 1000 cycles, the capacity retention of the PB thin-film electrode is 97.72% in (NH4)2SO4 solution, 93.52% in NH4Cl solution, and 53.14% in NH4AC solution, further demonstrating that the PB thin-film electrode has superior electrochemical performance in 0.25M (NH4)2SO4 solution.

[0082] Compare with Example 3

[0083] To further investigate the development of electrodes with both significant electrochromic properties and excellent long-cycle stability in suitable electrolytes, this comparative example aims to study the electrochemical performance of PB thin-film electrodes with ion storage layers in different cationic electrolytes.

[0084] The method used in this comparative example to prepare the PB thin film electrode is consistent with the method described above for preparing the PB thin film electrode based on the ammonium ion electrochromic device.

[0085] This comparative example tested the electrochemical performance of the PB thin-film electrode at two concentrations in different cationic electrolytes, namely 0.25 M and 0.5 M.

[0086] Figure 11 The figure shows a comparison of the areal specific capacitance of the PB thin film electrode in different cationic electrolytes. It can be seen that the PB thin film electrode has a higher areal specific capacitance in (NH4)2SO4 solution at both concentrations, and the areal specific capacitance is the highest in 0.25M (NH4)2SO4 solution, which further confirms that the PB thin film electrode has better electrochemical performance in 0.25M (NH4)2SO4 solution.

[0087] Compare with Example 4

[0088] To further determine the development of an electrode with excellent long-term cycling stability in 0.25M (NH4)2SO4 electrolyte, this comparative example aims to study the electrochemical performance of the ion storage layer PB thin film electrode in (NH4)2SO4 electrolytes of different concentrations.

[0089] The method used in this comparative example to prepare the PB thin film electrode is consistent with the method described above for preparing the PB thin film electrode based on the ammonium ion electrochromic device.

[0090] This comparative example tested the electrochemical performance of the PB thin film electrode in (NH4)2SO4 electrolytes of different concentrations, namely the cyclic voltammetry curves at 0.05M, 0.1M, 0.25M, 0.5M, 1M, 2M and 4M, and the capacity retention after 1000 cycles at 0.05M, 0.25M, 1M and 4M.

[0091] Figure 12 The figure shows a comparison of the CV curves of the PB thin film electrode in different concentrations of (NH4)2SO4 electrolyte. It can be seen that the CV curve of the PB thin film electrode in 0.25M (NH4)2SO4 solution has a larger envelope area at different concentrations, which further confirms that the PB thin film electrode has better electrochemical performance in 0.25M (NH4)2SO4 solution.

[0092] Figure 13The graph shows a comparison of the long-cycle capacity retention curves of the PB thin-film electrode in different concentrations of (NH4)2SO4 electrolyte for ion storage layers. It can be seen that among the tested concentrations, the PB thin-film electrode exhibits the best long-cycle performance in 0.25M (NH4)2SO4 solution, retaining 97.72% of its initial capacity after 1000 cycles. This further confirms that the PB thin-film electrode has excellent long-cycle stability in 0.25M (NH4)2SO4 solution.

[0093] The above embodiments of the present invention do not describe all details exhaustively, nor do they limit the present invention to the embodiments described above. Various changes, modifications, substitutions, and variations made by those skilled in the art to these embodiments without departing from the principles and spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. An electrochromic device based on an ammonium ion aqueous electrolyte, characterized in that: The electrochromic device comprises, from bottom to top, a transparent conductive glass substrate, an ion storage layer, a hydrogel ion electrolyte layer, an electrochromic layer, and a top transparent conductive layer; the ion storage layer material comprises a Prussian blue nanosheet film; the electrochromic layer material is Nb. 18 W 16 O 93 film; The preparation method of the hydrogel ion electrolyte layer is as follows: Weigh 6g of acrylamide and dissolve it in 18mL of deionized water to obtain a mixed solution. Weigh 0.012g of methylenebisacrylamide and 0.12g of ammonium persulfate and add them to the above mixed solution and stir thoroughly until completely dissolved. Then, purge with pure argon gas for 5 minutes and slowly inject into the mold with a syringe, taking care not to generate air bubbles. Seal with plastic wrap and keep in a constant temperature oven at 60℃ for 3 hours to obtain a hydrogel. Take an appropriate size of the hydrogel and immerse it in 0.25M (NH4)2SO4 solution for 5 hours to obtain the hydrogel ion electrolyte layer.

2. The electrochromic device based on ammonium ion aqueous electrolyte according to claim 1, characterized in that: The conductive material coated on the transparent conductive glass substrate includes an FTO film or an ITO film; the top transparent conductive layer material is an ITO thin film.

3. The electrochromic device based on ammonium ion aqueous electrolyte according to claim 1, characterized in that: The area of ​​the hydrogel ionoelectrolyte layer is 2×2 cm. 2 The thickness is 2mm.

4. A method for preparing an electrochromic device based on an ammonium ion aqueous electrolyte as described in claim 1, comprising the following steps: S1. Clean the transparent conductive glass substrate with a mixture of ether and ethanol in a volume ratio of 1:1 for 10 minutes using ultrasonic cleaning, and finally dry it with a hair dryer for later use. S2. Weigh 0.54g ferric chloride hexahydrate, 0.66g potassium ferricyanide, and 1.5g potassium chloride, add them to 200mL of deionized water, stir for 15min until completely dissolved, then add 0.1mL concentrated sulfuric acid to adjust the pH to an acidic environment, and stir thoroughly to obtain the Prussian blue precipitation solution. Electrochemical deposition was performed on a transparent conductive glass substrate in a Prussian blue deposition solution to obtain a transparent conductive glass substrate with a Prussian blue thin film electrode deposited on it. After washing with deionized water, the substrate was heat-treated in a 60°C constant temperature oven for 10 min. S3. Weigh 6g of acrylamide and dissolve it in 18mL of deionized water to obtain a mixed solution. Weigh 0.012g of methylenebisacrylamide and 0.12g of ammonium persulfate and add them to the above mixed solution and stir thoroughly until completely dissolved. Then, purge with pure argon gas for 5 minutes and slowly inject into the mold with a syringe, avoiding the generation of air bubbles. Seal with plastic wrap and keep in a constant temperature oven at 60℃ for 3 hours to obtain a hydrogel. Take an appropriate size of the hydrogel and immerse it in 0.25M (NH4)2SO4 solution for 5 hours to obtain the hydrogel ion electrolyte layer. S4. Mix 2 mL of deionized water with 8 mL of ethanol and stir thoroughly. Add 0.2 g of niobium oxalate hydrate and stir for 0.5 h. Add 0.49 g of ammonium metatungstate hydrate and stir for 0.5 h. Add 1.0 g of citric acid hydrate and heat in a water bath at 60 °C for 5 min to obtain Nb. 18 W 16 O 93 Precursor fluid; Nb was spin-coated onto ITO transparent conductive glass using a spin coating method. 18 W 16 O 93 After the precursor liquid is applied, it is placed in a tube furnace for heat treatment at a temperature of 600℃ for 2 hours to obtain a top transparent conductive layer with an electrochromic layer spin-coated. S5. A transparent conductive glass substrate with Prussian blue thin film electrode deposited, a hydrogel ion electrolyte layer, and a top transparent conductive layer with an electrochromic layer spin-coated are sequentially bonded from bottom to top, and a layer of sealant is applied around the perimeter to prepare an electrochromic device based on an ammonium ion aqueous electrolyte.

5. The application of the electrochromic device based on ammonium ion aqueous electrolyte as described in claim 1 in the fabrication of intelligent systems.

6. The application of the electrochromic device based on ammonium ion aqueous electrolyte as described in claim 1 in the fabrication of a smart window.

7. The application of the electrochromic device based on ammonium ion aqueous electrolyte as described in claim 1 in the preparation of smart electronic products.

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