Electrochromic device based on ammonium ion aqueous electrolyte and preparation method and application thereof

Abstract

The invention aims at providing an electrochromic device based on ammonium ion aqueous electrolyte and a preparation method and application of the electrochromic device, and belongs to the technical field of electrochromic devices. The transparent conductive glass 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. The electrolyte layer of the electrochromic device based on the ammonium ions adopts the hydrogel ion electrolyte, so that the migration process of the ammonium ions can be effectively promoted, and the long-cycle stability of the electrochromic device based on the ammonium ions is improved. The electrochromic device based on ammonium ions has wide application prospects in the fields of intelligent systems, intelligent windows, intelligent electronic products and the like.

Description

Technical Field

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

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

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

[0004] Electrochromic devices share similarities with supercapacitors in terms of electrode materials, structural design, and reaction kinetics, and are sometimes referred to as "rocking-chair" batteries. These similarities suggest that electrochromic technology can be combined with supercapacitors to develop energy storage devices with electrochromic properties. Users can intuitively 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 suggest that electrochromic energy storage devices have enormous potential for application in smart electronic devices.

[0005] Current electrochromic energy storage devices typically consist of five layers: a bottom transparent electrode / ion storage layer / ion electrolyte layer / electrochromic layer / top transparent electrode, forming a composite device with integrated optoelectronic functions. Applying a specific voltage difference across the device causes ions and electrons to migrate in and out of the device, enabling the device 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 the advantages of abundant resources, wide availability, eco-friendliness, small hydrated ion radius, light molar mass, fast diffusion rate and good circulation performance.

[0008] In recent years, due to the non-metallic ammonium ion (NH4 + Ammonium-ion electrochromic devices (AECDs) have attracted significant interest in smart energy storage systems due to their light molar mass, low cost, and environmentally friendly properties. However, developing AECDs that exhibit both significant electrochromic performance and excellent long-term cycling stability in suitable electrolytes is a daunting challenge. Therefore, developing an ammonium-ion electrochromic energy storage device is of great significance. Summary of the Invention

[0009] The object of the present invention is to provide an electrochromic device based on an ammonium ion aqueous electrolyte, a preparation method thereof, and an application thereof, wherein the electrochromic device has both significant electrochromic performance and excellent long-term cycle stability.

[0010] To achieve the above object, the present invention adopts the following technical solutions: An electrochromic device based on an ammonium ion aqueous electrolyte comprises, from bottom to top, a transparent conductive glass substrate layer, 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 immersing a hydrogel in a 0.25M (NH4)2SO4 solution for 5 hours.

[0011] Furthermore, the conductive material coated on the transparent conductive glass substrate layer includes an FTO film or an ITO film; and the top transparent conductive layer material is an ITO thin film.

[0012] Furthermore, the ion storage layer material includes a Prussian blue (PB) nanosheet film.

[0013] Furthermore, the area of ​​the hydrogel ion electrolyte layer is 2×2 cm 2 , thickness is 2mm.

[0014] Furthermore, the electrochromic layer material is Nb 18 W 16 O 93 film.

[0015] A method for preparing an electrochromic device based on an ammonium ion aqueous electrolyte comprises the following steps: S1. Ultrasonic cleaning of a transparent conductive glass substrate with a mixture of ether and ethanol in a volume ratio of 1:1 for 10 min, followed by drying with a hair dryer. S2. Weigh 0.54 g of ferric chloride hexahydrate, 0.66 g of potassium ferrocyanide, and 1.5 g of potassium chloride, add them to 200 mL of deionized water, and stir for 15 min until completely dissolved. Then, add 0.1 mL of concentrated sulfuric acid to adjust the pH to an acidic environment, and stir thoroughly to obtain a PB sediment solution; Electrochemical deposition was performed on a transparent conductive glass substrate in a PB deposition solution to obtain a transparent conductive glass substrate with a PB thin film electrode deposited thereon. The substrate was washed with deionized water and then heat-treated in a 60°C constant temperature oven for 10 minutes. S3. Weigh 6 g of acrylamide and dissolve it in 18 mL of deionized water to obtain a mixed solution. Weigh 0.012 g of methylenebisacrylamide and 0.12 g of ammonium persulfate and add them to the mixed solution and stir thoroughly until completely dissolved. Then, after passing pure argon gas for 5 minutes, slowly inject the mixture into the mold with a syringe to avoid generating bubbles. After sealing with plastic wrap, keep the mixture in a 60°C constant temperature box for 3 hours to obtain a hydrogel. Take a piece of the prepared hydrogel of appropriate size and soak it in a 0.25 M (NH4)2SO4 solution for 5 hours to obtain a hydrogel ion electrolyte layer. S4. Mix 2 mL of deionized water and 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 hydrated ammonium metatungstate 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; Spin coating Nb on ITO transparent conductive glass by spin coating 18 W 16 O 93 After the precursor solution, it was placed in a tube furnace for heat treatment at a temperature of 600°C and a holding time of 2 h to obtain a top transparent conductive layer spin-coated with an electrochromic layer; S5. The transparent conductive glass substrate with the PB thin film electrode deposited thereon, the hydrogel ion electrolyte layer and the top transparent conductive layer are laminated in sequence from bottom to top, and a layer of sealant is applied around them to prepare an electrochromic device based on an ammonium ion aqueous electrolyte.

[0016] The invention discloses an electrochromic device based on an ammonium ion aqueous electrolyte and its application in the preparation of intelligent systems, intelligent windows and intelligent electronic products.

[0017] The beneficial effects of the present invention are as follows: 1. This invention utilizes a hydrogel ion electrolyte in the electrolyte layer of an ammonium ion electrochromic device, effectively promoting ammonium ion migration. The resulting ammonium ion electrochromic device exhibits excellent long-cycle stability, maintaining a 99.79% capacity retention after 1,000 cycles.

[0018] 2. The ammonium ion electrochromic device constructed in the present invention has an ultra-thin all-inorganic structure, which not only has excellent cycle stability but also has a wide optical modulation amplitude, with the optical modulation amplitude reaching approximately 61.1% at 630nm.

[0019] 3. The present invention adopts a method combining 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 controllable process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the electrochromic long cycle performance test curve of PB thin film electrode.

[0021] Figure 2 It is Nb 18 W 16 O 93 Electrochromic long cycle performance test curve of thin film electrode.

[0022] Figure 3 This is a schematic diagram of the transmittance of the ammonium ion electrochromic device in the faded state at different voltages in Example 1.

[0023] Figure 4 This is a schematic diagram of the CV curve changes of the ammonium ion electrochromic device at different scan rates in Example 1.

[0024] Figure 5 This is the GCD curve of the charge and discharge performance of the ammonium ion electrochromic device in Example 1.

[0025] Figure 6 The GCD curves of the ammonium ion electrochromic device in Example 1 are single, series and parallel.

[0026] Figure 7 This is the optical memory curve of the ammonium ion electrochromic device under long-cycle cyclic voltammetry test in Example 1.

[0027] Figure 8 This is a schematic diagram of the long-cycle coulombic efficiency and capacity retention rate of the ammonium ion electrochromic device based on Example 1.

[0028] Figure 9 This is the optical memory curve of the ammonium ion electrochromic device based on the control example.

[0029] Figure 10 This is a comparison chart of the long-cycle capacity retention rate of the ion storage layer PB thin film electrode in three anion electrolytes.

[0030] Figure 11 This is a comparison chart of the area-to-capacitance of the ion storage layer PB thin film electrode in different cationic electrolytes.

[0031] Figure 12 CV curves of the ion storage layer PB thin film electrode in (NH4)2SO4 solutions with different concentrations.

[0032] Figure 13 This is the capacity retention curve of the ion storage layer PB thin film electrode after 1000 cycles in 0.05M, 0.25M, 1M, and 4M (NH4)2SO4 solutions. DETAILED DESCRIPTION

[0033] The following embodiments 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, but are not intended to limit the scope of protection of the present invention.

[0034] Unless otherwise specified, the production processes, experimental methods or detection methods involved in the embodiments of the present invention are all conventional methods in the prior art, and their names and / or abbreviations are conventional names in the field and are very clear and unambiguous in the relevant fields of use. 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 the conditions recommended by the manufacturer.

[0035] The various instruments, equipment, raw materials or reagents used in the embodiments of the present invention are not particularly limited in their sources and are all conventional products that can be purchased through regular commercial channels or prepared according to conventional methods well known to those skilled in the art.

[0036] The various ammonium ion-based electrochromic devices provided in the following embodiments of the present invention are specifically prepared according to the following methods.

[0037] The ITO transparent conductive glass substrate to be used was ultrasonically cleaned with a mixture of ether and ethanol in a volume ratio of 1:1 for 10 minutes, and finally dried with a hair dryer for later use.

[0038] Weigh 0.54 g of ferric chloride hexahydrate, 0.66 g of potassium ferrocyanide, and 1.5 g of potassium chloride, add them to 200 mL of deionized water, and stir for 15 min until completely dissolved. Then, add 0.1 mL of concentrated sulfuric acid to adjust the pH to an acidic environment, and stir thoroughly to obtain a PB sedimentation solution.

[0039] The PB thin film electrode of the ion storage layer was deposited 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 the ITO transparent conductive glass in the PB deposition solution. The deposition was carried out for 300 seconds at a polarization current of -0.16 mA to obtain a PB thin film electrode deposited on the ITO transparent conductive glass.

[0040] Slowly place the ITO transparent conductive glass with the PB thin film electrode deposited on it into a beaker filled with deionized water until it is completely submerged, and wash the deposited liquid on the PB film back and forth twice.

[0041] The washed ITO transparent conductive glass deposited with the PB thin film electrode is placed in a constant temperature oven at 60° C. for heat treatment. The heat treatment of the PB thin film electrode of the ion storage layer is completed by heat treatment for 10 minutes.

[0042] The PB thin film electrode obtained by heat treatment has excellent electrochromic and energy storage properties. Figure 1 The corresponding test curve is given. It can be seen that during the electrochemical reaction of cyclic voltammetry, the optical transmittance of the PB thin film electrode changes repeatedly and stably in the range of 16.2% (colored state) to 79.6% (faded state), and the optical modulation amplitude can reach 63.2%. After 5000 continuous coloring-bleaching cycles, the transmittance modulation amplitude of the PB electrode still maintains 82.02% of the initial value, indicating that the PB thin film electrode has stable and reversible electrochromic properties during the electrochemical reaction process.

[0043] The hydrogel ion electrolyte layer was prepared by soaking the hydrogel in 0.25 M (NH4)2SO4 solution for 5 h.

[0044] The specific process for preparing the hydrogel ion electrolyte layer is as follows: weigh 6 g of acrylamide and dissolve it in 18 mL of deionized water; weigh 0.012 g of methylenebisacrylamide and 0.12 g of ammonium persulfate and add them to the above mixture and stir thoroughly until completely dissolved; then, after passing pure argon gas for 5 minutes, slowly inject it into the mold with a syringe (do not generate bubbles); seal it with plastic wrap and keep it in a constant temperature box at 60°C for 3 hours to obtain a hydrogel; take a suitable size of the prepared hydrogel and soak it in 0.25 M (NH4)2SO4 solution for 5 hours to obtain a hydrogel ion electrolyte layer.

[0045] Electrochromic layer Nb 18 W 16 O 93 The films were 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 hydrated ammonium metatungstate 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 to prepare the precursor solution.

[0046] Place the cleaned ITO transparent conductive glass on a spin coater (conductive side facing up), and use a pipette to evenly drop the precursor liquid on the ITO transparent conductive glass. The spin coating parameters are low speed 300 rpm, high speed 2500 rpm, low speed duration 20 s, high speed duration 40 s, and spin coating twice.

[0047] Spin-coated Nb 18 W 16 O 93 The ITO transparent conductive glass with precursor solution is placed in a tube furnace for heat treatment at a temperature of 600° C. and a holding time of 2 hours.

[0048] The specific temperature control is as follows: the temperature is raised to 180℃ after 0.5h at room temperature, kept at 180℃ for 0.5h and then raised to 250℃ after 0.5h, kept at 250℃ for 0.5h and then raised to 400℃ after 0.5h, kept at 400℃ for 0.5h and then raised to 600℃ after 1h, kept at 600℃ for 2h and then cooled to 100℃ after 2h, and the Nb is completed after cooling to room temperature. 18 W 16 O 93 Thermal treatment of thin films.

[0049] The Nb obtained by heat treatment 18 W 16 O 93 The thin film electrode has excellent electrochromic properties. Figure 2 Given the corresponding test curve, 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 changes repeatedly and stably in the range of 29.7% (colored state) to 61.4% (bleached state), and the optical modulation amplitude can reach 31.7%. After 1000 consecutive coloring-bleaching cycles, Nb 18 W 16 O 93 The transmittance modulation amplitude of the thin film electrode still maintains 87.07% of the initial value, indicating that Nb 18 W 16 O 93 The thin film electrode has stable and reversible electrochromic properties during the electrochemical reaction.

[0050] After the above preparation process, the PB ion storage layer, the hydrogel ion electrolyte layer and the top transparent conductive layer with the electrochromic layer spin-coated are deposited on the transparent conductive ITO glass in sequence from bottom to top, and a layer of sealant is applied around the device to prepare an ammonium ion-based electrochromic device.

[0051] The prepared ammonium ion electrochromic energy storage device was affixed with copper tape at both ends of the bottom and top transparent conductive layers to lead out positive and negative test electrodes, attached to a test frame, and placed in a UV-visible spectrophotometer. The positive and negative test electrodes led out of the device were connected to an electrochemical workstation for in-situ testing and characterization.

[0052] Example 1 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), thickness 2mm; Nb 18 W 16 O 93Thin film layer; ITO transparent conductive layer.

[0053] The electrochromic and electrochemical properties of the ammonium ion-based electrochromic device were in situ tested using an electrochemical workstation and UV-visible spectrophotometer.

[0054] from Figure 3 The full-spectrum transmittance diagram of an ammonium-based electrochromic device during coloring and fading shows that the spectral transmittance of the electrochromic device in the visible light range gradually changes. As the voltage gradually increases, the device continues to color, accompanied by a gradual decrease in its transmittance in the visible light range. Under different voltages, the device's transmittance in the visible light range has a large modulation amplitude. For example, as the device changes from the faded state to the colored state at 1.7V, its optical modulation amplitude at 630nm reaches approximately 51.1%.

[0055] Figure 4 This is a schematic diagram of the changes in the cyclic voltammetry (CV) curve of an ammonium ion electrochromic device at 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.

[0056] Figure 5 The researchers present parameter curves used to test the charge-discharge behavior of an ammonium-based electrochromic device. Specifically, the prepared device was connected to an electrochemical workstation and subjected to charge and discharge tests using the chronopotentiometry method. The device's charge-discharge curves were also measured at various current densities. The device's charge-discharge curves exhibited good symmetry at various current densities, indicating minimal electrochemical polarization of the device electrodes. The slopes of the charge-discharge curves were nonlinear at various current densities, indicating the coexistence of pseudocapacitor-like and battery-like charge storage characteristics.

[0057] Figure 6 To adopt Figure 5 The parameters shown are used to test the charge and discharge curves of the ammonium ion-based electrochromic devices prepared above in single, series and parallel conditions. It can be seen that the output voltage of the ammonium ion-based electrochromic devices in series doubles, and the charge and discharge time is equal; while the ammonium ion-based electrochromic devices in parallel maintain a stable voltage and the charge and discharge time is doubled. The charge and discharge curves of the devices in series and parallel conditions are basically the same as the charge and discharge curves of a single device; combined with Figure 6 As can be seen from the diagrams of series and parallel connection, the envelope areas of the charge-discharge curves in series and parallel state are consistent. The above results indicate that the prepared electrochromic device based on ammonium ions has good uniformity.

[0058] In order to further study the performance of ammonium ion-based electrochromic devices, the optical memory effect of the above-prepared devices was tested under cyclic voltammetry. Figure 3 This indicates that the device voltage can affect its transmittance. Therefore, the voltage change during the cyclic voltammetry test of the device will cause a corresponding change in its optical transmittance. The optical memory effect of the device can be used to reflect its electrochemical performance.

[0059] Figure 7 The optical memory curve of an ammonium ion electrochromic device under cyclic voltammetry is presented. The device has an initial modulation amplitude of 61.1%, and after 1000 cycles, 97.4% of the modulation amplitude is retained, further demonstrating the device's excellent cycling stability.

[0060] Figure 8 The coulombic efficiency and capacitance retention curves of the ammonium ion electrochromic device under cyclic voltammetry test are given. -2 At a current density of 1.5 GHz, the prepared ammonium ion electrochromic energy storage device retained 99.79% of its capacity after 1000 cycles and 80.14% of its initial capacity after 3000 cycles. Its Coulombic efficiency was close to 100%, demonstrating the excellent electrochemical performance of the prepared device. The inset shows the series-connected devices successfully lighting a red LED, demonstrating their scalable integration capabilities in the field of smart electronics.

[0061] Comparative Example 1 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), thickness 2mm; Nb 18 W 16 O 93 Thin film layer; ITO transparent conductive layer.

[0062] The structures and materials of the electrochromic device in this comparative example are exactly the same as those in Example 1, except that the immersion time of the hydrogel ion electrolyte layer in the 0.25M (NH4)2SO4 solution is changed to 4 hours.

[0063] Figure 7 and Figure 9 A comparison chart of the optical memory effects of the electrochromic devices prepared in Example 1 and the control example is provided.

[0064] Figure 7 The optical memory curve of an ammonium ion-based electrochromic device, using a hydrogel electrolyte immersed in a 0.25M (NH₄)₂SO₄ solution for 5 hours, is presented under cyclic voltammetry. The device exhibits an initial transmittance of 61.1%, and after 1000 cycles, it maintains a transmittance of 97.4%, further demonstrating the device's excellent cycling stability.

[0065] Figure 9The optical memory curve of an ammonium ion-based electrochromic device using a hydrogel electrolyte immersed in a 0.25M (NH4)2SO4 solution for 4 hours under cyclic voltammetry testing. The initial modulation amplitude at 630nm was 56.8%, and after 500 cycles, 68.8% of the modulation amplitude was retained. Comparison of the optical memory effects of the two devices further demonstrates that the device in Example 1 has superior electrochemical performance.

[0066] Comparative Example 2 In order to further study 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 anion electrolytes.

[0067] The method for preparing the PB thin film electrode used in this comparative example is consistent with the above-mentioned method for preparing the PB thin film electrode based on ammonium ion electrochromic device.

[0068] In this control experiment, 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.

[0069] Figure 10 The figure shows the comparison of the long cycle capacity retention rate of the ion storage layer PB thin film electrode in three anion electrolytes. It can be seen that after 1000 cycle tests, the capacity retention rate of the PB thin film electrode in (NH4)2SO4 solution is 97.72%, the capacity retention rate in NH4Cl solution is 93.52%, and the capacity retention rate in NH4AC solution is 53.14%, further proving that the PB thin film electrode has better electrochemical performance in 0.25M (NH4)2SO4 solution.

[0070] Comparative Example 3 In order to further study the development of electrodes with both significant electrochromic properties and excellent long-cycle stability in suitable electrolytes, this control example aims to study the electrochemical performance of the ion storage layer PB thin film electrode in different cationic electrolytes.

[0071] The method for preparing the PB thin film electrode used in this comparative example is consistent with the above-mentioned method for preparing the PB thin film electrode based on ammonium ion electrochromic device.

[0072] This comparative example tests the electrochemical performance of PB thin film electrodes in different cationic electrolytes at two concentrations, 0.25M and 0.5M respectively.

[0073] Figure 11This is a comparison chart of the area specific capacitance of the ion storage layer PB thin film electrode in different cationic electrolytes. It can be seen that at both concentrations, the PB thin film electrode has a higher area specific capacitance in (NH4)2SO4 solution, and the area specific capacitance in 0.25M (NH4)2SO4 solution is the highest, further confirming that the PB thin film electrode has better electrochemical performance in 0.25M (NH4)2SO4 solution.

[0074] Comparative Example 4 To further confirm the development of an electrode with excellent long-cycle stability in 0.25M (NH4)2SO4 electrolyte, this control example aims to study the electrochemical performance of the ion storage layer PB thin film electrode in (NH4)2SO4 electrolytes with different concentrations.

[0075] The method for preparing the PB thin film electrode used in this comparative example is consistent with the above-mentioned method for preparing the PB thin film electrode based on ammonium ion electrochromic device.

[0076] This control example tests the electrochemical performance of the PB thin film electrode in different concentrations of (NH4)2SO4 electrolyte, including the cyclic voltammetry curves at 0.05M, 0.1M, 0.25M, 0.5M, 1M, 2M and 4M, and the capacity retention rate after 1000 cycles at 0.05M, 0.25M, 1M and 4M.

[0077] Figure 12 This is a comparison of the CV curves of the PB thin film electrode with the ion storage layer in different concentrations of (NH4)2SO4 electrolyte. It can be seen that the envelope area of ​​the CV curve of the PB thin film electrode in 0.25M (NH4)2SO4 solution at different concentrations is larger, which further confirms that the PB thin film electrode has better electrochemical performance in 0.25M (NH4)2SO4 solution.

[0078] Figure 13 This is a comparison of the long-cycle capacity retention curves of the ion storage layer PB thin film electrode in different concentrations of (NH4)2SO4 electrolyte. It can be seen that among the several concentrations tested, the PB thin film electrode has the best long-cycle performance in 0.25M (NH4)2SO4 solution. After 1000 cycles, it still retains 97.72% of the initial capacity, further confirming that the PB thin film electrode has excellent long-cycle stability in 0.25M (NH4)2SO4 solution.

[0079] The above embodiments of the present invention do not describe all details in detail, nor do they limit the present invention to the above embodiments. Various changes, modifications, substitutions, and variations made by those skilled in the art without departing from the principles and purpose of the present invention are intended to 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 includes, from bottom to top, a transparent conductive glass substrate layer, 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 the hydrogel in a 0.25M (NH4)2SO4 solution for 5 hours.

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

3. The electrochromic device based on an ammonium ion aqueous electrolyte according to claim 1, characterized in that: The ion storage layer material includes a Prussian blue nanosheet film.

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

5. The electrochromic device based on an ammonium ion aqueous electrolyte according to claim 1, characterized in that: The electrochromic layer material is Nb 18 W 16 O 93 film.

6. A method for preparing an electrochromic device based on an ammonium ion aqueous electrolyte according to claim 1, comprising the following steps: S1. Ultrasonic cleaning of a transparent conductive glass substrate with a mixture of ether and ethanol in a volume ratio of 1:1 for 10 min, followed by drying with a hair dryer. S2. Weigh 0.54 g of ferric chloride hexahydrate, 0.66 g of potassium ferrocyanide, and 1.5 g of potassium chloride, add them to 200 mL of deionized water, and stir for 15 min until completely dissolved. Then, add 0.1 mL of concentrated sulfuric acid to adjust the pH to an acidic environment, and stir thoroughly to obtain a PB sediment solution; Electrochemical deposition was performed on a transparent conductive glass substrate in a PB deposition solution to obtain a transparent conductive glass substrate with a PB thin film electrode deposited thereon. The substrate was washed with deionized water and then heat-treated in a 60°C constant temperature oven for 10 minutes. S3. Weigh 6 g of acrylamide and dissolve it in 18 mL of deionized water to obtain a mixed solution. Weigh 0.012 g of methylenebisacrylamide and 0.12 g of ammonium persulfate and add them to the mixed solution and stir thoroughly until completely dissolved. Then, after passing pure argon gas for 5 minutes, slowly inject the mixture into the mold with a syringe to avoid generating bubbles. After sealing with plastic wrap, keep the mixture in a 60°C constant temperature box for 3 hours to obtain a hydrogel. Take a piece of the prepared hydrogel of appropriate size and soak it in a 0.25 M (NH4)2SO4 solution for 5 hours to obtain a hydrogel ion electrolyte layer. S4. Mix 2 mL of deionized water and 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 hydrated ammonium metatungstate 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; Spin coating Nb on ITO transparent conductive glass by spin coating 18 W 16 O 93 After the precursor solution, it was placed in a tube furnace for heat treatment at a temperature of 600°C and a holding time of 2 h to obtain a top transparent conductive layer spin-coated with an electrochromic layer; S5. The transparent conductive glass substrate with the PB thin film electrode deposited thereon, the hydrogel ion electrolyte layer and the top transparent conductive layer with the electrochromic layer spin-coated thereon are sequentially laminated from bottom to top, and a layer of sealant is applied around them to prepare an electrochromic device based on an ammonium ion aqueous electrolyte.

7. Use of the electrochromic device based on ammonium ion aqueous electrolyte according to claim 1 in the preparation of intelligent systems, intelligent windows and intelligent electronic products.

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