Titanium modified molybdenum-doped tungsten oxide nanoparticles, electrochromic thin film, electrochromic device and preparation method

Abstract

The application discloses a kind of titanium modified molybdenum-doped tungsten oxide nanoparticles, electrochromic film, electrochromic device and preparation method.Nanoparticle chemical composition is, x=0.05~0.15, y=0.05~0.15, x+y=0.10~0.20, with Porous or mesoporous structure, specific surface area 50~150 m² / g.Sol-gel method is used to prepare, and is obtained by heat treatment at 400~600 DEG C.Electrochromic film is made by the nanoparticle by spraying method, thickness 200~800 nm, porosity 20%~50%.All-solid-state electrochromic device includes transparent conductive substrate, the electrochromic film, solid electrolyte layer, ion storage layer and second transparent conductive substrate, and is assembled by hot-pressing composite.The application widens lithium ion transmission channel by Ti-Mo binary synergic doping, electrochromic film optical modulation range 4%~75%, response time ≤60 seconds, cycle life ≥50,000 times, and suitable for large-area production.

Description

Technical Field

[0001] This invention relates to the field of electrochromic materials and devices, specifically to titanium-modified molybdenum-doped tungsten oxide nanoparticles, electrochromic thin films, electrochromic devices, and their preparation methods. Background Technology

[0002] Electrochromism refers to the phenomenon of a material undergoing a stable and reversible color change under the influence of an applied electric field. Tungsten trioxide (WO3) is the most classic and widely used cathode electrochromic material, possessing advantages such as large light modulation amplitude, high coloring efficiency, good reversibility, and the ability to operate continuously in harsh environments. Compared to organic electrochromic materials, WO3 films can maintain stable and reversible color changes during multiple cycles, thus becoming a key material system for development in the field of electrochromism. A typical WO3-based electrochromic device film structure is: glass / transparent conductive layer / electrochromic layer / electrolyte layer / ion storage layer / transparent conductive layer.

[0003] However, traditional WO3 electrochromic materials suffer from the following technical defects, which severely restrict the performance improvement and industrialization of electrochromic devices: (1) The optical modulation range is narrow, and the transmittance adjustment range is only 25%~60%, which cannot meet the requirements of building energy conservation and intelligent dimming for wide-range light modulation.

[0004] (2) The response time is long, with coloring response time > 120 seconds and fading response time > 120 seconds. The user experience is poor and it cannot be applied to scenarios that require fast response (such as anti-glare rearview mirrors, dynamic displays, etc.).

[0005] (3) The cycle life is low. The electrochromic performance deteriorates significantly after about 10,000 cycles, which cannot meet the requirements of long-life application scenarios such as building curtain walls (which require a service life of more than 20 years).

[0006] (4) Low ion transport efficiency. The WO3 lattice spacing is small (about 0.38 nm), and lithium ions are subject to significant steric hindrance during insertion / extraction, resulting in a low ion diffusion coefficient (about 10 nm). - ¹ 0 (on the order of cm² / s), which is the root cause of slow response and short lifespan.

[0007] (5) Poor UV blocking rate, <90%, unable to effectively block UV rays from harming indoor occupants and interior decorations.

[0008] To address these issues, researchers have attempted to modify WO3 materials through metal doping. For example, titanium (Ti)-doped WO3 films have been shown to improve ion implantation / extraction reversibility, cycle stability, and response speed; molybdenum (Mo)-doped WO3 films have been shown to increase the diffusion coefficient of ions within the WO3 film and improve electrochromic properties. However, existing single-element doping schemes offer limited performance improvements, and insufficient optimization of doping content and fabrication processes makes it difficult to simultaneously achieve improvements in wide optical modulation range, fast response, and long cycle life.

[0009] In addition, the existing preparation of WO3 electrochromic thin films mainly adopts magnetron sputtering. Although this method can obtain high-quality thin films, it requires large equipment investment, has complex processes, high target material preparation costs, and is not suitable for large-area continuous production. Furthermore, the thin films prepared by magnetron sputtering are usually relatively dense with low porosity, which is not conducive to the rapid transport of ions. Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a titanium-modified molybdenum-doped tungsten oxide nanoparticle, an electrochromic film, an electrochromic device, and a preparation method thereof. Specifically, it includes a titanium-modified molybdenum-doped tungsten oxide nanoparticle, an electrochromic film containing the nanoparticle, an all-solid-state electrochromic device containing the electrochromic film, and a corresponding preparation method thereof.

[0011] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: In a first aspect, the present invention provides titanium-modified molybdenum-doped tungsten oxide nanoparticles for use in electrochromic devices, wherein the chemical composition of the nanoparticles is as follows: , where x = 0.05~0.15, y = 0.05~0.15, and x + y = 0.10~0.20; The nanoparticles have a porous or mesoporous structure, with a specific surface area of ​​50~150 m² / g, an average particle size of 20~100 nm, and a grain size of 10~50 nm. The nanoparticles were prepared by the following method: tungsten source, titanium source and molybdenum source were dissolved in a solvent in stoichiometric ratio to form a precursor solution, a dispersant and a pore-forming agent were added, and a gel was formed by sol-gel reaction. After drying, the gel was obtained by heat treatment at 400~600℃. When the titanium-modified molybdenum-doped tungsten oxide nanoparticles are used to prepare electrochromic films, compared with undoped tungsten oxide, the ion diffusion coefficient is increased by more than an order of magnitude, the coloring efficiency is increased by more than 50%, and the cycle life is increased by more than 5 times.

[0012] The beneficial effects of this invention are as follows: through the synergistic doping of titanium and molybdenum, molybdenum atoms replace some tungsten atoms to form a solid solution to adjust the band structure and enhance conductivity. Titanium atoms are introduced in the form of titanium dioxide to refine the grains, inhibit abnormal grain growth, and form a ternary system of tungsten oxide-molybdenum-titanium dioxide. Combined with porous or mesoporous structure design, two doping atoms of different sizes and valence states are introduced into the tungsten oxide lattice at the same time, generating lattice distortion and defect energy levels, thereby broadening the lithium ion insertion / extraction channels, reducing the steric hindrance of ion transport, and enabling nanoparticles to have excellent comprehensive performance of high conductivity, high ion diffusion coefficient and high structural stability.

[0013] Based on the above technical solution, the present invention can be further improved as follows.

[0014] Furthermore, when the doping ratio of titanium and molybdenum is 10 at% each (total doping amount 20 at%), experimental verification shows that the optimal overall performance can be obtained, with the ion diffusion coefficient reaching 1.3 × 10⁻⁶. cm² / s, conductivity reaches 2.8× The S / cm ratio and cycle life reach 50,000 cycles. Too low a doping concentration (5%) cannot sufficiently alter the band structure and lattice parameters, resulting in limited performance improvement; too high a doping concentration (15%) leads to excessive distortion of the tungsten oxide lattice, which in turn hinders ion transport. The introduction of a porous structure further increases the electrochemically active specific surface area and ion transport pathways, achieving an optimal balance in performance.

[0015] Furthermore, the tungsten source is selected from one or more of ammonium tungstate, ammonium metatungstate, tungsten hexachloride, and sodium tungstate; The titanium source is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride, and titanium dioxide sol. The molybdenum source is selected from one or more of ammonium molybdate, ammonium heptamolybdate, ammonium molybdate tetrahydrate, and molybdenum chloride; The dispersant is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, and polyvinyl alcohol; The pore-forming agent is selected from one or more of polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and hexadecyltrimethylammonium bromide.

[0016] The beneficial effects of adopting the above-mentioned further scheme are as follows: the tungsten source, titanium source and molybdenum source have good solubility and compatibility in solvents, and can achieve uniform distribution of titanium and molybdenum elements in tungsten oxide matrix at the molecular level, avoiding segregation of dopant elements or formation of independent phases; the addition of dispersant stabilizes the nanoparticle suspension through electrostatic repulsion or steric hindrance effect, preventing agglomeration; the addition of pore-forming agent generates gas through thermal decomposition during heat treatment, forming a multi-level micro-nano pore structure in nanoparticles and films, providing more transport paths and reactive sites for ion transport.

[0017] Secondly, the present invention also provides a method for preparing titanium-modified molybdenum-doped tungsten oxide nanoparticles for electrochromic devices, comprising the following steps: S1: Dissolve tungsten source, titanium source and molybdenum source in a mixed solvent of organic solvent and deionized water in stoichiometric ratio, add dispersant and pore-forming agent, and stir evenly to obtain precursor solution, wherein the concentration of tungsten source is 0.1~0.5 mol / L; S2: Adjust the pH of the precursor solution obtained in step S1 to 1~3, stir and react at 40~80℃ for 2~6 hours to form a transparent or translucent wet gel. S3: Dry the wet gel obtained in step S2 at 60~120℃ for 12~48 hours to obtain a dry gel; S4: The dry gel obtained in step S3 is calcined in air at 400~600℃ for 2~4 hours at a heating rate of 1~5℃ / min to obtain titanium-modified molybdenum-doped tungsten oxide nanoparticles. In step S2, the reaction temperature, pH value and reaction time are controlled during the sol-gel reaction to adjust the network structure and pore size distribution of the gel. In step S4, the pore-forming agent undergoes thermal decomposition to generate gas during the heat treatment process, forming a porous or mesoporous structure in the nanoparticles.

[0018] The beneficial effects of this invention are as follows: Doped nanoparticles are prepared by combining the sol-gel method with heat treatment. The hydrolysis and condensation reaction rates in the sol-gel process are controlled by adjusting parameters such as precursor concentration, reaction pH, reaction temperature, and time, thereby controlling the network structure and pore size distribution of the gel. In the subsequent heat treatment process, the precursor decomposes into oxides, and the pore-forming agent decomposes to generate gas, forming a multi-level micro-nano pore structure in the nanoparticles. This process avoids the high energy consumption of traditional vacuum coating processes and is suitable for large-scale production.

[0019] Based on the above technical solution, the present invention can be further improved as follows.

[0020] Furthermore, the organic solvent mentioned in step S1 is selected from one or more of ethanol, isopropanol, and ethylene glycol methyl ether, and the volume ratio of the organic solvent to deionized water is 1:1 to 5:1. In step S2, the pH adjuster is selected from one or more of hydrochloric acid, nitric acid, and acetic acid, with nitric acid being preferred; In step S4, the calcination temperature is 450~500℃, the calcination time is 3 hours, and the heating rate is 2℃ / min.

[0021] The beneficial effects of adopting the above-mentioned further scheme are as follows: the volume ratio of organic solvent to deionized water is controlled within the range of 1:1 to 5:1, which not only ensures the full dissolution of tungsten, titanium and molybdenum sources, but also provides an appropriate amount of water molecules for the hydrolysis reaction; the pH value is adjusted to 1 to 3 with nitric acid, which is conducive to the formation of a uniform gel network structure and avoids local precipitation or phase separation; the calcination temperature is controlled at 450 to 500℃ (within the optimized range of 400 to 600℃), which not only ensures that the precursor is completely converted into oxide and forms the required crystal phase structure (mainly monoclinic WO3), but also inhibits excessive grain growth, retains the nanoscale grain size and porous structure, and avoids the collapse of the porous structure due to excessive temperature.

[0022] Thirdly, the present invention also provides an electrochromic film comprising a titanium-modified molybdenum-doped tungsten oxide nanoparticle for use in an electrochromic device, or composed of titanium-modified molybdenum-doped tungsten oxide nanoparticles prepared by a method for preparing titanium-modified molybdenum-doped tungsten oxide nanoparticles for use in an electrochromic device. The electrochromic film has a thickness of 200~800 nm, a surface roughness Ra<10 nm, and a porosity of 20%~50%. The electrochromic film is obtained by dispersing the titanium-modified molybdenum-doped tungsten oxide nanoparticles in a solvent to form a suspension, and then depositing it on the substrate surface by spraying, spin coating, dip coating or blade coating, and then heat-treating it at 200~400℃. The electrochromic film has the following electrochromic properties: optical modulation range of 4%~75%, coloring response time ≤60 seconds, fading response time ≤60 seconds, coloring efficiency of 80~120 cm² / C, and cycle life ≥50,000 times.

[0023] The beneficial effects of this invention are as follows: After preparing an electrochromic film by titanium-modified molybdenum-doped tungsten oxide nanoparticles, the porous structure and high specific surface area of ​​the nanoparticles increase the number of active sites for electrochemical reactions. At the same time, the lattice defects introduced by doping reduce the energy barrier for lithium ion insertion / extraction. Thus, while maintaining a wide optical modulation range (4%~75%), the electrochromic film achieves fast response (≤60 seconds) and ultra-long cycle life (≥50,000 times), solving the core problems of traditional WO3 electrochromic films, such as narrow optical modulation range (25%~60%), slow response (>120 seconds), and short cycle life (approximately 10,000 times).

[0024] Based on the above technical solution, the present invention can be further improved as follows.

[0025] Furthermore, the electrochromic film is prepared using a spraying method, specifically including the following steps: S10: A titanium-modified molybdenum-doped tungsten oxide nanoparticle for electrochromic devices is dispersed in an organic solvent at a concentration of 5-20 g / L, a dispersant is added, and ultrasonic dispersion is performed for 30-60 minutes to obtain a nano-ink with a viscosity of 50-200 mPa·s. S20: Load the nano-ink obtained in step S10 into a spray gun and perform spray deposition at a substrate temperature of 100~300℃. The spraying distance is 10~30 cm, the spraying pressure is 0.1~0.5 MPa, and the nozzle moving speed is 10~50 mm / s. S30: After the coating is completed, the substrate with the deposited film is heat-treated at 200~400℃ for 30~60 minutes to obtain an electrochromic film.

[0026] The advantages of adopting the above-mentioned further scheme are as follows: Electrochromic films are prepared by spraying (i.e., in-situ thermal oxidation spraying technology). After the nano-ink is atomized, it impacts the high-temperature substrate, the solvent evaporates rapidly, and the nanoparticles are deposited on the substrate surface and in-situ heat treatment is completed at the same time. This realizes the simultaneous occurrence of deposition and heat treatment, avoiding the shortcomings of traditional magnetron sputtering methods that require high vacuum equipment and complex target material preparation, and significantly reducing equipment investment and production costs. At the same time, by adjusting the spraying parameters (substrate temperature, spraying distance, spraying pressure, nozzle moving speed), the thickness, uniformity and porosity of the film can be precisely controlled, which is suitable for the large-scale production of large-area (>1 m²) electrochromic films.

[0027] Fourthly, the present invention also provides an all-solid-state electrochromic device, comprising: First transparent conductive substrate; An electrochromic layer disposed on the first transparent conductive substrate, wherein the electrochromic layer is an electrochromic thin film; A solid electrolyte layer disposed on the electrochromic layer; An ion storage layer disposed on the solid electrolyte layer; A second transparent conductive substrate disposed on the ion storage layer; The solid electrolyte layer is selected from one or more of polyvinyl butyral solid electrolyte, lithium phosphorus oxy nitrogen solid electrolyte, or polyethylene oxide solid electrolyte. The ion storage layer is selected from one or more of nickel oxide, vanadium pentoxide, or Prussian blue.

[0028] The beneficial effects of this invention are: by integrating the electrochromic thin film prepared by titanium-modified molybdenum-doped tungsten oxide nanoparticles with a solid electrolyte layer and an ion storage layer, an all-solid-state electrochromic device is constructed. By utilizing the wide optical modulation range and fast response characteristics of the electrochromic thin film, combined with the excellent safety and long cycle stability of the solid electrolyte, the overall performance of the device is synergistically improved, meeting the comprehensive needs of energy saving, safety and intelligence in application scenarios such as building curtain walls, automotive glass, and aircraft windows.

[0029] Based on the above technical solution, the present invention can be further improved as follows.

[0030] Furthermore, the solid electrolyte layer is a polyvinyl butyral-based solid electrolyte, which forms a tight interfacial contact with the electrochromic film, with an interfacial bonding strength ≥6 MPa. The porous structure of titanium-modified molybdenum-doped tungsten oxide nanoparticles in the electrochromic film forms a three-dimensional interconnected network with the lithium-ion transport channels in the solid electrolyte layer, thereby achieving low-impedance transport of lithium ions between the electrochromic film and the solid electrolyte layer. After being placed continuously for 1000 hours in an environment of 85℃ / 85% relative humidity, the visible light transmittance of the all-solid-state electrochromic device fluctuates by <3%; and the coloring response time is ≤15 seconds in a low-temperature environment of -40℃.

[0031] The beneficial effects of adopting the above-mentioned further scheme are as follows: the porous structure of the electrochromic film not only increases the active sites for electrochemical reactions, but also forms a three-dimensional interconnected ion transport network with the solid electrolyte layer (especially the PVB-based solid electrolyte), enabling lithium ions to be rapidly and uniformly inserted and extracted inside the device; at the same time, due to the synergistic doping of titanium and molybdenum, the electrochromic film has good structural and chemical stability in high temperature and high humidity and low temperature environments. Combined with the excellent weather resistance of the PVB-based solid electrolyte, the device can operate stably for a long time in a wide temperature range of -40℃ to 85℃ and in a high humidity environment of 85%, significantly expanding the application scenarios of electrochromic devices.

[0032] Fifthly, the present invention also provides a method for preparing an all-solid-state electrochromic device, comprising the following steps: S100: A titanium-modified molybdenum-doped tungsten oxide electrochromic film is prepared on a first transparent conductive substrate by spraying according to a method for preparing an electrochromic film. S200: An ion storage layer is prepared on a second transparent conductive substrate by magnetron sputtering or spraying. S300; Cut the solid electrolyte membrane to the required size and sandwich it between the electrochromic film obtained in step S100 and the ion storage layer obtained in step S200. S400: Place the components obtained in steps S100 to S300 in a vacuum laminator and perform hot pressing composite under the conditions of vacuum degree <100 Pa, temperature 120~160℃, and pressure 0.3~0.8 MPa for 20~60 minutes. S500: After naturally cooling to room temperature, it is removed to obtain an all-solid-state electrochromic device; In step S100, the substrate temperature for preparing the electrochromic film by spraying is 100~300℃, and the heat treatment temperature is 200~400℃. During the hot-pressing composite process in step S400, the solid electrolyte membrane softens and flows under the action of temperature and pressure, forming a tight interfacial bond with the porous surface of the electrochromic film and the surface of the ion storage layer, filling the micro-unevenness and pores on the surface of the electrochromic film and reducing the interfacial impedance.

[0033] The beneficial effects of this invention are as follows: It employs a hybrid process route of "spray coating for electrochromic thin film preparation + hot-pressing composite integration," combining the low-cost, large-area applicable spray coating method with mature vacuum hot-pressing composite technology. This avoids the complex process and high cost of traditional all-solid-state electrochromic devices requiring multi-layer vacuum coating. The electrochromic thin film prepared by the spray coating method has a controllable porous surface structure, forming a dual interface bond with the solid electrolyte film during the hot-pressing composite process, which ensures sufficient interface bonding strength and reduces interface impedance through the three-dimensional interconnection of ion transport channels in the solid electrolyte via the porous structure. This method is suitable for the industrial production of large-scale, low-cost, large-area all-solid-state electrochromic devices. Attached Figure Description

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Figure 1 This is a schematic diagram of the preparation process of titanium-modified molybdenum-doped WO3 nanofilm in this invention. Detailed Implementation

[0036] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages involved in the patent do not simply refer to direct contact between components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0037] The first aspect of the present invention is a titanium-modified molybdenum-doped tungsten oxide nanoparticle for use in electrochromic devices.

[0038] Through in-depth theoretical research and numerous experiments, it has been discovered that tungsten oxide nanoparticles prepared using the "Ti-Mo binary metal synergistic doping" strategy can simultaneously improve conductivity, broaden ion transport channels, and enhance structural stability through the synergistic effect of titanium and molybdenum in the tungsten oxide lattice. This results in breakthroughs in key performance indicators such as optical modulation range, response time, and cycle life.

[0039] The chemical composition of the titanium-modified molybdenum-doped tungsten oxide nanoparticles of this invention is as follows: Where x = 0.05~0.15, y = 0.05~0.15, and x+y = 0.10~0.20. Doping amounts of titanium and molybdenum within this range can fully utilize the dopant elements' control over band structure and lattice parameters while avoiding excessive lattice distortion and ion transport obstruction caused by excessive doping.

[0040] The theoretical basis of the "multi-metal co-doping" model is as follows: based on the atomic-level design theory of bimetallic co-doped tungsten oxide, molybdenum atoms replace some tungsten atoms to form a solid solution. ),because Its ionic radius (approximately 0.059 nm) is slightly smaller than (Approximately 0.060 nm), molybdenum doping introduces local compressive strain into the crystal lattice, modulating the band structure and introducing doped energy levels into the band gap of WO3, thus enhancing the material's electronic conductivity. Simultaneously, molybdenum doping can suppress abnormal growth of WO3 grains, refine the microstructure, and make the grain size more uniform. Titanium atoms are introduced in the form of TiO2, forming... In the ternary system, TiO2 itself possesses high mechanical strength and chemical stability, which can enhance the mechanical strength and thermal shock resistance of the electrochromic layer; simultaneously, titanium doping introduces... Ionic radius (approximately 0.0605 nm) and Similarly, titanium doping creates localized expansion strain in the lattice, forming a "strain pair" with the compressive strain introduced by molybdenum doping. This results in localized structural distortion in the lattice, and the distorted region becomes a "fast channel" for lithium ion insertion / extraction, significantly reducing the activation energy for ion migration.

[0041] Density functional theory (DFT) simulations show that after Mo / Ti bimetallic co-doping of WO3, the electronic density of states near the Fermi level of WO3 increases significantly, the band gap narrows from about 2.6 eV in pure WO3 to about 2.2 eV, and the electronic conductivity is improved by about 1 to 2 orders of magnitude. The lithium ion insertion energy in doped WO3 (about -1.8 eV) is lower than that in pure WO3 (about -1.2 eV), indicating that lithium ions are more easily inserted into the lattice after doping. The diffusion barrier of lithium ions decreases from about 0.6 eV in pure WO3 to about 0.3 eV, which explains the increase in ion diffusion coefficient after doping.

[0042] The nanoparticles possess a porous or mesoporous structure with a specific surface area of ​​50–150 m² / g, an average particle size of 20–100 nm, a grain size of 10–50 nm, a pore size distribution range of 2–50 nm, and a pore volume of 0.1–0.5 cm³ / g. The porous structure is formed by the introduction of pore-forming agents during preparation and thermal decomposition during heat treatment. The beneficial effects of the porous structure include: significantly increasing the active specific surface area for electrochemical reactions, providing more reaction sites for lithium ion insertion / extraction; the pores in the porous structure can serve as rapid lithium ion transport channels, shortening the diffusion distance of ions in the solid phase; and the porous structure can buffer the volume expansion / contraction caused by repeated lithium ion insertion / extraction, improving cycle stability.

[0043] It should be noted that, as shown in Table 1, when the doping ratio of titanium and molybdenum is 10 at% each (total doping amount 20 at%), the optimal overall performance can be obtained through experiments, at which point the ion diffusion coefficient reaches 1.3 × 10⁻⁶. cm² / s, conductivity reaches 2.8× The S / cm ratio and cycle life reach 50,000 cycles. Too low a doping concentration (5%) cannot sufficiently alter the band structure and lattice parameters, resulting in limited performance improvement; too high a doping concentration (15%) leads to excessive distortion of the tungsten oxide lattice, which in turn hinders ion transport. The introduction of a porous structure further increases the electrochemically active specific surface area and ion transport pathways, achieving an optimal balance in performance.

[0044] Table 1

[0045] The second aspect of this invention is a method for preparing titanium-modified molybdenum-doped tungsten oxide nanoparticles according to the first aspect.

[0046] Research has shown that by using the sol-gel method combined with heat treatment to prepare doped nanoparticles, it is possible to achieve a uniform molecular-level distribution of titanium and molybdenum in a tungsten oxide matrix, and to obtain nanoparticles with porous structures by introducing pore-forming agents and controlling heat treatment conditions.

[0047] Specifically, see Figure 1 The preparation method of the present invention includes the following steps: Preparation of S1 precursor solution: Tungsten source, titanium source and molybdenum source are dissolved in a mixed solvent of organic solvent and deionized water in stoichiometric ratio, dispersant and pore-forming agent are added, and the mixture is stirred evenly to obtain a precursor solution, wherein the concentration of tungsten source is 0.1~0.5 mol / L.

[0048] Specifically, the tungsten source is selected from one or more of ammonium tungstate, ammonium metatungstate, tungsten hexachloride, and sodium tungstate, with ammonium metatungstate being preferred because it has good solubility in organic solvents and leaves few residual impurities after thermal decomposition. The titanium source is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride, and titanium dioxide sol, with tetrabutyl titanate being preferred because its hydrolysis rate is moderate and the sol-gel reaction process is easy to control. The molybdenum source is selected from one or more of ammonium molybdate, ammonium heptamolybdate, ammonium molybdate tetrahydrate, and molybdenum chloride, with ammonium heptamolybdate being preferred because it has high solubility in water and a high molybdenum content.

[0049] The organic solvent is selected from one or more of ethanol, isopropanol, and ethylene glycol methyl ether, with ethanol being preferred due to its low toxicity, low cost, and volatility. The volume ratio of the organic solvent to deionized water is 1:1 to 5:1, preferably 2:1 to 3:1. The dispersant is selected from one or more of polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), and polyvinyl alcohol (PVA), with PEG-400 being preferred because of its moderate molecular weight and good dispersing effect. The pore-forming agent is selected from one or more of polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymers (F127, P123), and cetyltrimethylammonium bromide (CTAB), with F127 being preferred because it has a regular micelle structure and can form an ordered mesoporous structure after thermal decomposition.

[0050] S2 Sol-Gel Reaction: The pH of the precursor solution obtained in step S1 is adjusted to 1-3, and the mixture is stirred at 40-80℃ for 2-6 hours to form a transparent or translucent wet gel. Specifically, the pH adjuster is selected from one or more of hydrochloric acid, nitric acid, and acetic acid, with nitric acid being preferred because nitrate ions are easily decomposed and volatilized during subsequent heat treatment, preventing the introduction of additional impurities into the product. Maintaining the pH within the range of 1 to 3 helps control the hydrolysis rate and form a uniform gel network structure. The reaction temperature is controlled within the range of 40 to 80°C. Too low a temperature results in a slow hydrolysis-condensation reaction rate and a long gel formation time; too high a temperature leads to a too fast reaction rate, easily forming a precipitate rather than a uniform gel.

[0051] S3 Drying: The wet gel obtained in step S2 is dried at 60~120℃ for 12~48 hours to obtain a dry gel; Specifically, the wet gel obtained in step S2 is dried at 60-120°C for 12-48 hours to obtain a dry gel. During the drying process, the solvent gradually evaporates, and the gel network structure shrinks but maintains its basic framework.

[0052] S4 heat treatment: The dry gel obtained in step S3 was calcined in air at 400-600℃ for 2-4 hours at a heating rate of 1-5℃ / min to obtain titanium-modified molybdenum-doped tungsten oxide nanoparticles. Specifically, the main changes that occur during heat treatment include: (1) the precursor decomposes into oxides (WO3, TiO2, MoO3); (2) the organic components (dispersant, pore-forming agent, residual solvent) thermally decompose to produce gases (CO2, H2O, NO). x (3) Oxides crystallize to form a specific crystal phase structure; (4) Gas escapes and leaves a porous or mesoporous structure in the nanoparticles. The calcination temperature is controlled between 400 and 600℃. If the temperature is too low, the crystallization will be incomplete and the electrochromic performance will be insufficient; if the temperature is too high, the grains will grow excessively, the porous structure will collapse, and the specific surface area will decrease. The preferred calcination temperature is 450 to 500℃. Within this temperature range, nanoparticles with complete crystal phase structure (mainly monoclinic WO3), well preserved porous structure, and high specific surface area can be obtained.

[0053] In step S2, the reaction temperature, pH value and reaction time are controlled during the sol-gel reaction to adjust the network structure and pore size distribution of the gel. In step S4, the pore-forming agent undergoes thermal decomposition to generate gas during the heat treatment process, forming a porous or mesoporous structure in the nanoparticles.

[0054] The third aspect of the present invention is an electrochromic thin film comprising titanium-modified molybdenum-doped tungsten oxide nanoparticles as described in the first aspect.

[0055] The electrochromic film of the present invention is obtained by dispersing the titanium-modified molybdenum-doped tungsten oxide nanoparticles in a solvent to form a suspension (nano-ink), and then depositing it on the substrate surface by spraying, spin coating, dip coating or blade coating, followed by heat treatment at 200~400℃. Spraying (i.e., in-situ thermal oxidation spraying technology) is preferred because this method is suitable for large-scale production.

[0056] The electrochromic film has a thickness of 200~800 nm (which can be adjusted according to actual needs), a surface roughness Ra<10 nm, and a porosity of 20%~50%.

[0057] See Figure 1 The specific steps for preparing electrochromic thin films by spray coating include: Formulation of S10 nano ink: Specifically, titanium-modified molybdenum-doped tungsten oxide nanoparticles are dispersed in an organic solvent at a concentration of 5-20 g / L, a dispersant is added, and the mixture is ultrasonically dispersed for 30-60 minutes to obtain a nano-ink with a viscosity of 50-200 mPa·s. Specifically, titanium-modified molybdenum-doped tungsten oxide nanoparticles are dispersed in an organic solvent (preferably ethanol or isopropanol) at a concentration of 5-20 g / L, and a dispersant (preferably PVP or PEG) is added. The mixture is then ultrasonically dispersed for 30-60 minutes to obtain a nano-ink with a viscosity of 50-200 mPa·s. Controlling the viscosity within this range ensures both smooth atomization of the ink and good spreading and deposition efficiency on the substrate surface.

[0058] S20 spray coating deposition: The nano-ink obtained in step S10 is loaded into a spray gun and sprayed and deposited at a substrate temperature of 100~300℃. The spraying distance is 10~30 cm, the spraying pressure is 0.1~0.5 MPa, and the nozzle moving speed is 10~50 mm / s. Specifically, nano-ink is loaded into a spray gun and deposited at a substrate temperature of 100–300°C. The spraying distance is 10–30 cm, the spraying pressure is 0.1–0.5 MPa, and the nozzle movement speed is 10–50 mm / s. During the spraying process, the nano-ink atomizes into micron-sized droplets. As the droplets fly towards the high-temperature substrate, the solvent begins to evaporate. Upon impact with the substrate, the solvent evaporates rapidly and completely, and the nanoparticles are deposited on the substrate surface to form a thin film, simultaneously completing in-situ heat treatment (i.e., "in-situ thermal oxidation spraying"). The substrate temperature is controlled at 100–300°C. If the temperature is too low, the solvent will not evaporate sufficiently, and the film will not dry completely; if the temperature is too high, it may cause the film to crack or the nanoparticles to be over-sintered.

[0059] S30 subsequent heat treatment: After the coating is completed, the substrate with the deposited film is heat-treated at 200~400℃ for 30~60 minutes to obtain an electrochromic film.

[0060] Specifically, after the coating is completed, the substrate with the deposited film is heat-treated at 200~400℃ for 30~60 minutes to further remove residual organic matter, promote the sintering connection between nanoparticles, and improve the mechanical strength and electrical properties of the film.

[0061] The fourth aspect of the present invention is an all-solid-state electrochromic device comprising the electrochromic thin film described in the third aspect.

[0062] The all-solid-state electrochromic device of the present invention includes: First transparent conductive substrate (preferably ITO or FTO conductive glass). An electrochromic layer disposed on the first transparent conductive substrate, namely the electrochromic film described in the third aspect; A solid electrolyte layer (preferably a PVB-based solid electrolyte) is disposed on the electrochromic layer. An ion storage layer (preferably NiO, V2O5 or Prussian blue) is disposed on the solid electrolyte layer. A second transparent conductive substrate disposed on the ion storage layer.

[0063] The fabrication method of this all-solid-state electrochromic device includes the following steps: Preparation of S100 electrochromic thin film: According to the method described in the third aspect, a titanium-modified molybdenum-doped tungsten oxide electrochromic film is prepared on a first transparent conductive substrate by a spray coating method.

[0064] Fabrication of the S200 ion storage layer: An ion storage layer is prepared on a second transparent conductive substrate by magnetron sputtering or spraying. Specifically, an ion storage layer is prepared on a second transparent conductive substrate by magnetron sputtering or spraying. Magnetron sputtering is preferred for preparing the NiO thin film: the sputtering target is a NiO ceramic target, and the base vacuum level is 5× With a working pressure of 0.5 Pa (Ar:O2=10:1), sputtering power of 2.5 W / cm², substrate temperature of 250℃, and deposition time of 20~30 minutes, a NiO thin film with a thickness of approximately 200~400 nm was obtained.

[0065] Preparation of the S300 solid electrolyte layer: The solid electrolyte membrane is cut to the required size and sandwiched between the electrochromic film obtained in step S100 and the ion storage layer obtained in step S200. Specifically, the pre-prepared solid electrolyte membrane (preferably a PVB-based solid electrolyte membrane) is cut to the required size.

[0066] S400 Hot-pressed Composite Assembly: The components obtained in steps S100 to S300 are placed in a vacuum laminator and hot-pressed under conditions of vacuum degree <100 Pa, temperature 120~160℃, and pressure 0.3~0.8 MPa for 20~60 minutes. Specifically, the second transparent conductive substrate (containing an ion storage layer), the solid electrolyte membrane, and the first transparent conductive substrate (containing an electrochromic film) are stacked sequentially, with the solid electrolyte membrane sandwiched between the ion storage layer and the electrochromic film. The stacked assembly is then placed in a vacuum laminator and hot-pressed under conditions of vacuum <100 Pa, temperature 120~160℃, and pressure 0.3~0.8MPa for 20~60 minutes.

[0067] During the hot-pressing composite process, the solid electrolyte membrane (especially the PVB-based solid electrolyte) softens and flows under the influence of temperature and pressure, filling the microscopic irregularities and pores on the porous surface of the electrochromic film, forming a tight interfacial contact and chemical bond with the electrochromic film and the ion storage layer. Due to the porous structure of the electrochromic film, the solid electrolyte can penetrate into the pores during the softening and flowing process, forming a three-dimensional interconnected ion transport network, significantly reducing interfacial impedance and improving ion transport efficiency.

[0068] S500 Cooling and Removal: After naturally cooling to room temperature, the device was removed to obtain an all-solid-state electrochromic device. Specifically, after hot pressing and lamination, the device is naturally cooled to room temperature in a vacuum laminator, and after the vacuum is released, it is taken out to obtain the finished all-solid-state electrochromic device.

[0069] In step S100, the substrate temperature for preparing the electrochromic film by spraying is 100~300℃, and the heat treatment temperature is 200~400℃. During the hot-pressing composite process in step S400, the solid electrolyte membrane softens and flows under the action of temperature and pressure, forming a tight interfacial bond with the porous surface of the electrochromic film and the surface of the ion storage layer, filling the micro-unevenness and pores on the surface of the electrochromic film and reducing the interfacial impedance.

[0070] Example 1 This embodiment provides a chemical composition of The preparation method of titanium-modified molybdenum-doped tungsten oxide nanoparticles includes the following specific steps: 1. Raw material preparation Tungsten source: Ammonium metatungstate ( (WO3 content approximately 85 wt%) Titanium source: Tetrabutyl titanate ( (Purity > 98%) Molybdenum source: Ammonium heptamolybdate ( (Purity > 99%) Organic solvent: anhydrous ethanol Dispersant: Polyethylene glycol PEG-400 Pore-forming agent: F127 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) 2. Preparation of precursor solution The amount of each raw material was calculated according to the molar ratio of Ti:Mo:W = 0.1:0.1:0.8. Appropriate amounts of ammonium metatungstate, ammonium heptamolybdate, and tetrabutyl titanate were weighed and dissolved in a mixed solvent of ethanol and deionized water (ethanol:water = 3:1, volume ratio). PEG-400 (5% of the tungsten source mass) and F127 (10% of the tungsten source mass) were added, and the mixture was stirred at room temperature for 30 minutes to obtain a precursor solution with a concentration of 0.3 mol / L (in W).

[0071] 3. Sol-gel reaction The pH of the precursor solution was adjusted to 2 using 2 mol / L nitric acid, and the mixture was stirred in a 60°C water bath for 4 hours to form a transparent wet gel.

[0072] 4. Drying The wet gel was transferred to a petri dish and dried in an 80°C oven for 24 hours to obtain a dry gel.

[0073] 5. Heat treatment The dried gel was placed in a muffle furnace and heated to 500°C at a heating rate of 2°C / min. It was then calcined at 500°C for 3 hours and naturally cooled to room temperature before being removed to obtain titanium-modified molybdenum-doped tungsten oxide nanoparticles.

[0074] Product characterization results: Chemical composition (ICP-OES analysis): (The measured value is basically consistent with the theoretical value) Crystal structure (XRD analysis): The main diffraction peaks are consistent with the monoclinic phase WO3 (JCPDS No. 43-1035). No independent diffraction peaks of TiO2 or MoO3 were observed, indicating that Ti and Mo have been dissolved into the WO3 lattice. Specific surface area (BET method): 98 m² / g Average particle size (TEM observation): 45 nm Grain size (Scherrer formula): 22 nm Pore ​​size distribution (BJH method): predominantly mesoporous, with the most probable pore size approximately 15 nm. Example 2 This embodiment provides a method for preparing an electrochromic thin film containing the nanoparticles of Example 1, the specific steps of which are as follows: 1. Formulation of nano ink The titanium-modified molybdenum-doped tungsten oxide nanoparticles prepared in Example 1 were dispersed in anhydrous ethanol at a concentration of 10 g / L. Polyvinylpyrrolidone (PVP, added at 2% of the nanoparticle mass) was added as a dispersant and ultrasonically dispersed for 45 minutes to obtain a uniform nano-ink with a viscosity of about 120 mPa·s.

[0075] 2. Substrate preparation ITO conductive glass (size 10 cm × 10 cm, surface resistance 10 Ω / □) was selected as the substrate and ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 15 minutes in sequence. After being dried with nitrogen, it was placed on a heating platform and heated to 200℃.

[0076] 3. Spraying deposition The nano-ink was loaded into a spray gun (nozzle diameter 0.5 mm) and deposited under the following conditions: spraying distance 20 cm, spraying pressure 0.25 MPa, nozzle movement speed 30 mm / s, and 10 spray passes (with a 10-second interval between each pass to allow solvent evaporation). The substrate temperature was maintained at 200°C during the spraying process.

[0077] 4. Subsequent heat treatment After the coating is completed, the ITO glass with the deposited film is placed in a muffle furnace and heat-treated at 300°C for 30 minutes. After natural cooling, it is taken out to obtain a titanium-modified molybdenum-doped tungsten oxide electrochromic film.

[0078] Thin film characterization results: Thin film thickness (profilometer measurement): approximately 350 nm Surface roughness (AFM test): Ra = 6.8 nm Porosity (calculated from density): Approximately 35% Conductivity (four-probe method): 2.5× S / cm Example 3 This embodiment tests the electrochromic properties of the electrochromic thin film prepared in Example 2.

[0079] The test system used a three-electrode electrochemical cell: an electrochromic thin film as the working electrode, a platinum sheet as the counter electrode, Ag / AgCl as the reference electrode, and a 1 mol / L LiClO4 / PC solution as the electrolyte. The test results are shown in Table 2. Table 2

[0080] The results show that the titanium-modified molybdenum-doped tungsten oxide electrochromic film prepared by this invention is significantly superior to the pure WO3 film in key performance indicators such as optical modulation range, response time, coloring efficiency, ion diffusion coefficient and cycle life.

[0081] Example 4 This embodiment investigates the effect of the Ti and Mo doping ratio on the performance of electrochromic thin films through a series of experiments.

[0082] Following the method of Example 1, keeping the total doping amount x+y=0.20 constant, the relative ratio of Ti and Mo (i.e., the values ​​of x and y) was changed to prepare a series of chemical compositions. The nanoparticles were then used to prepare an electrochromic film according to the method in Example 2, and its performance was tested.

[0083] Table 3

[0084] Referring to Table 3, the results show that when the doping levels of Ti and Mo are each 10 at% (x=0.10, y=0.10, total doping level 20 at%), the ion diffusion coefficient, conductivity, and cycle lifetime all reach their optimal values. Excessively high single doping levels (such as Ti 15 at% / Mo 5 at% or Ti 5 at% / Mo 15 at%) lead to excessive lattice distortion, which in turn degrades performance. This indicates that an appropriate Ti to Mo ratio (1:1) is crucial for achieving synergistic doping effects.

[0085] Example 5 This embodiment provides a method for preparing an all-solid-state electrochromic device including the electrochromic thin film of Example 2, and tests its overall performance.

[0086] 1. Preparation of electrochromic thin films Titanium-modified molybdenum-doped tungsten oxide electrochromic thin films were prepared on ITO conductive glass (first substrate) with dimensions of 15 cm × 15 cm, according to the method of Example 2.

[0087] 2. Preparation of ion storage layer A NiO ion storage layer was deposited on another ITO conductive glass substrate of the same size (second substrate) using magnetron sputtering. Sputtering conditions: base vacuum 5× Pa, working air pressure 0.5 Pa ( =10:1), sputtering power 2.5 W / cm², substrate temperature 250℃, deposition time 25 minutes, NiO film thickness approximately 300 nm.

[0088] 3. Preparation of the solid electrolyte layer The PVB-based solid electrolyte membrane (thickness 0.38 mm) prepared according to Example 1 of Technical Solution 1 was cut into 15 cm × 15 cm dimensions.

[0089] 4. Hot-pressed composite assembly The following components are stacked in the following order: second substrate (NiO side up), solid electrolyte membrane, and first substrate (electrochromic film side down). The stacked assembly is placed in a vacuum laminator, evacuated to 50 Pa, heated to 140°C, and subjected to a pressure of 0.5 MPa for 30 minutes. After natural cooling, it is removed to obtain an all-solid-state electrochromic device.

[0090] Device performance test results: Visible light transmittance range: transparent state 74.2%, colored state 4.5% (modulation range 69.7%). Shading response time: 56 seconds (-2.5 V) Fading response time: 50 seconds (+2.5 V) Cycle life: After 50,000 cycles, the optical modulation range retains 92% of its initial value. UV blocking rate: 99.1% High temperature and high humidity test (85℃ / 85% RH, 1000 hours): transmittance fluctuation 2.3%, device function is normal. Low temperature test (-40℃): The coloring response time is 14 seconds, and it can still change color normally. Power consumption: 0.30 W·h / m² Comparative testing: A control device prepared simultaneously with a pure WO3 electrochromic thin film was tested under the same conditions. Its optical modulation range was 28%–58%, its color response time was 128 seconds, and its cycle life was approximately 11,000 cycles. The results show that the all-solid-state electrochromic device prepared in this invention significantly outperforms the pure WO3 control device in terms of overall performance.

[0091] Example 6 This embodiment verifies the feasibility of using the method of the present invention to prepare large-area all-solid-state electrochromic devices.

[0092] Following the method in Example 5, an all-solid-state electrochromic device with dimensions of 1.2 m × 1.6 m (area 1.92 m²) was fabricated. After the device fabrication was completed, nine test points (3×3 grid distribution) were selected for performance uniformity testing.

[0093] Table 4

[0094] Referring to Table 4, the test results show that the performance uniformity of each region of the large-area device is good: the maximum deviation of transmittance in the transparent state is 0.8% (relative deviation 1.1%), the maximum deviation of transmittance in the colored state is 0.6% (relative deviation 15%, but the absolute deviation is acceptable due to the small absolute value), and the maximum deviation of response time is 7 seconds. This indicates that the method of the present invention has good process stability and scalability, and is suitable for the industrial production of large-area electrochromic devices.

[0095] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A titanium-modified molybdenum-doped tungsten oxide nanoparticle for use in electrochromic devices, characterized in that, The chemical composition of the nanoparticles is as follows: , where x = 0.05~0.15, y = 0.05~0.15, and x + y = 0.10~0.20; The nanoparticles have a porous or mesoporous structure, with a specific surface area of ​​50~150 m² / g, an average particle size of 20~100 nm, and a grain size of 10~50 nm. The nanoparticles were prepared by the following method: tungsten source, titanium source and molybdenum source were dissolved in a solvent in stoichiometric ratio to form a precursor solution, a dispersant and a pore-forming agent were added, and a gel was formed by sol-gel reaction. After drying, the gel was obtained by heat treatment at 400~600℃. When the titanium-modified molybdenum-doped tungsten oxide nanoparticles are used to prepare electrochromic films, compared with undoped tungsten oxide, the ion diffusion coefficient is increased by more than an order of magnitude, the coloring efficiency is increased by more than 50%, and the cycle life is increased by more than 5 times.

2. The titanium-modified molybdenum-doped tungsten oxide nanoparticles according to claim 1, characterized in that, The values ​​of x=0.10, y=0.10, and x+y=0.20 indicate that the chemical composition of the nanoparticles is... ; The pore size distribution of the porous or mesoporous structure ranges from 2 to 50 nm, and the pore volume is 0.1 to 0.5 cm³ / g.

3. The titanium-modified molybdenum-doped tungsten oxide nanoparticles according to claim 1 or 2, characterized in that, The tungsten source is selected from one or more of ammonium tungstate, ammonium metatungstate, tungsten hexachloride, and sodium tungstate; The titanium source is selected from one or more of tetrabutyl titanate, tetraisopropyl titanate, titanium tetrachloride, and titanium dioxide sol. The molybdenum source is selected from one or more of ammonium molybdate, ammonium heptamolybdate, ammonium molybdate tetrahydrate, and molybdenum chloride; The dispersant is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, and polyvinyl alcohol; The pore-forming agent is selected from one or more of polyethylene glycol, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and hexadecyltrimethylammonium bromide.

4. A method for preparing titanium-modified molybdenum-doped tungsten oxide nanoparticles according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Dissolve tungsten source, titanium source and molybdenum source in a mixed solvent of organic solvent and deionized water in stoichiometric ratio, add dispersant and pore-forming agent, and stir evenly to obtain precursor solution, wherein the concentration of tungsten source is 0.1~0.5 mol / L; S2: Adjust the pH of the precursor solution obtained in step S1 to 1~3, stir and react at 40~80℃ for 2~6 hours to form a transparent or translucent wet gel. S3: Dry the wet gel obtained in step S2 at 60~120℃ for 12~48 hours to obtain a dry gel; S4: The dry gel obtained in step S3 is calcined in air at 400~600℃ for 2~4 hours at a heating rate of 1~5℃ / min to obtain titanium-modified molybdenum-doped tungsten oxide nanoparticles. In step S2, the reaction temperature, pH value and reaction time are controlled during the sol-gel reaction to adjust the network structure and pore size distribution of the gel. In step S4, the pore-forming agent undergoes thermal decomposition to generate gas during the heat treatment process, forming a porous or mesoporous structure in the nanoparticles.

5. The preparation method according to claim 4, characterized in that, The organic solvent mentioned in step S1 is selected from one or more of ethanol, isopropanol, and ethylene glycol methyl ether, and the volume ratio of the organic solvent to deionized water is 1:1 to 5:

1. In step S2, the pH adjuster is selected from one or more of hydrochloric acid, nitric acid, and acetic acid, with nitric acid being preferred; In step S4, the calcination temperature is 450~500℃, the calcination time is 3 hours, and the heating rate is 2℃ / min.

6. An electrochromic thin film, characterized in that, It comprises titanium-modified molybdenum-doped tungsten oxide nanoparticles as described in any one of claims 1 to 3, or titanium-modified molybdenum-doped tungsten oxide nanoparticles prepared by the preparation method described in claim 4 or 5; The electrochromic film has a thickness of 200~800 nm, a surface roughness Ra<10 nm, and a porosity of 20%~50%. The electrochromic film is obtained by dispersing the titanium-modified molybdenum-doped tungsten oxide nanoparticles in a solvent to form a suspension, and then depositing it on the substrate surface by spraying, spin coating, dip coating or blade coating, and then heat-treating it at 200~400℃. The electrochromic film has the following electrochromic properties: optical modulation range of 4%~75%, coloring response time ≤60 seconds, fading response time ≤60 seconds, coloring efficiency of 80~120 cm² / C, and cycle life ≥50,000 times.

7. The electrochromic thin film according to claim 6, characterized in that, The electrochromic film is prepared by a spraying method, specifically including the following steps: S10: Disperse the titanium-modified molybdenum-doped tungsten oxide nanoparticles according to any one of claims 1 to 3 in an organic solvent at a concentration of 5 to 20 g / L, add a dispersant, and ultrasonically disperse for 30 to 60 minutes to obtain a nano-ink with a viscosity of 50 to 200 mPa·s. S20: Load the nano-ink obtained in step S10 into a spray gun and perform spray deposition at a substrate temperature of 100~300℃. The spraying distance is 10~30 cm, the spraying pressure is 0.1~0.5 MPa, and the nozzle moving speed is 10~50 mm / s. S30: After the coating is completed, the substrate with the deposited film is heat-treated at 200~400℃ for 30~60 minutes to obtain an electrochromic film.

8. A fully solid-state electrochromic device, characterized in that, include: First transparent conductive substrate; An electrochromic layer disposed on the first transparent conductive substrate, wherein the electrochromic layer is the electrochromic film as described in claim 6 or 7; A solid electrolyte layer disposed on the electrochromic layer; An ion storage layer disposed on the solid electrolyte layer; A second transparent conductive substrate disposed on the ion storage layer; The solid electrolyte layer is selected from one or more of polyvinyl butyral solid electrolyte, lithium phosphorus oxy nitrogen solid electrolyte, or polyethylene oxide solid electrolyte. The ion storage layer is selected from one or more of nickel oxide, vanadium pentoxide, or Prussian blue.

9. The all-solid-state electrochromic device according to claim 8, characterized in that, The solid electrolyte layer is a polyvinyl butyral solid electrolyte, which forms a tight interfacial contact with the electrochromic film, with an interfacial bonding strength ≥6 MPa. The porous structure of titanium-modified molybdenum-doped tungsten oxide nanoparticles in the electrochromic film forms a three-dimensional interconnected network with the lithium-ion transport channels in the solid electrolyte layer, thereby achieving low-impedance transport of lithium ions between the electrochromic film and the solid electrolyte layer. After being placed continuously at 85℃ / 85% relative humidity for 1000 hours, the visible light transmittance of the all-solid-state electrochromic device fluctuated by less than 3%. At a low temperature of -40℃, the coloring response time is ≤15 seconds.

10. A method for preparing an all-solid-state electrochromic device according to claim 8 or 9, characterized in that, Includes the following steps: S100: According to the method of claim 7, a titanium-modified molybdenum-doped tungsten oxide electrochromic film is prepared on a first transparent conductive substrate by spraying. S200: An ion storage layer is prepared on a second transparent conductive substrate by magnetron sputtering or spraying. S300; Cut the solid electrolyte membrane to the required size and sandwich it between the electrochromic film obtained in step S100 and the ion storage layer obtained in step S200. S400: Place the components obtained in steps S100 to S300 in a vacuum laminator and perform hot pressing composite under the conditions of vacuum degree <100 Pa, temperature 120~160℃, and pressure 0.3~0.8 MPa for 20~60 minutes. S500: After naturally cooling to room temperature, it is removed to obtain an all-solid-state electrochromic device; In step S100, the substrate temperature for preparing the electrochromic film by spraying is 100~300℃, and the heat treatment temperature is 200~400℃. During the hot-pressing composite process in step S400, the solid electrolyte membrane softens and flows under the action of temperature and pressure, forming a tight interfacial bond with the porous surface of the electrochromic film and the surface of the ion storage layer, filling the micro-unevenness and pores on the surface of the electrochromic film and reducing the interfacial impedance.

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