Electrolyte for tungsten trioxide-based electrochromic devices

Abstract

The application discloses an electrolyte for a tungsten trioxide-based electrochromic device, which comprises an organic solvent and an electrolyte; the electrolyte comprises an ammonium salt. The electrolyte of the application can be used to construct a high-performance long-life tungsten trioxide-based electrochromic device. When an electrochromic reaction occurs in a tungsten trioxide color-changing electrode, the electrolyte serves as an electrochemical reaction medium for the color-changing electrode and a counter electrode, and ensures the electrical neutrality of the two electrodes by transporting cations required for the color-changing reaction. The electrolyte of the application not only effectively overcomes the problems of a narrow stable voltage range, many side reactions, a slow reaction speed, a short color-changing cycle life and the like of a conventional electrolyte, but also has the outstanding advantages of a large applicable temperature range, high water-oxygen resistance, a simple preparation process, mild conditions, suitability for industrialized mass production and the like. The application further discloses the application of the electrolyte in the tungsten trioxide-based electrochromic device.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology application, specifically relating to an electrolyte for tungsten trioxide-based electrochromic devices. Background Technology

[0002] Electrochromic glass can flexibly adjust its optical properties under the influence of an applied electric field. Applying electrochromic glass to building and automotive glass allows for flexible control of sunlight intake based on changes in ambient temperature, thereby reducing energy consumption and improving indoor light and heat comfort. In eyeglasses and rearview mirrors, electrochromic technology can also provide anti-glare effects. Furthermore, electrochromic materials can create patterns through natural color differences before and after color change, achieving stable display and optical stealth effects. Combining electrochromic technology with smart electronic devices creates intelligent color-changing devices, further enhancing the user experience.

[0003] Tungsten trioxide (TTO) is a perovskite-type electrochromic material composed of tungsten and oxygen. It achieves a "deep blue to transparent" color transition primarily through the co-intercalation and co-extraction reaction of electrons with color-changing ions (generally metal cations), exhibiting fast color change response and high color contrast. Furthermore, TTO possesses advantages such as low preparation cost, mild synthesis conditions, high environmental friendliness and biosafety, and strong environmental durability, making it an important electrochromic material. However, during cycling, TTO is prone to "ion trapping," meaning that some metal cations intercalated within the TTO are difficult to extract during cycling, causing irreversible and rapid decay of the film's electrochromic performance, thus affecting the material's cycling stability (Nat. Mater. , 2015, 14(10), 996-1001).

[0004] To overcome the above problems, Professor Wen Ruitao applied a constant current and voltage to the cycled tungsten trioxide material to drive ion extraction, thereby repairing the material performance degradation caused by "ion trapping" and effectively improving the color change response time and cycle life of the coating in the traditional propylene carbonate / LiClO4 electrolyte (Nat. Mater. , 2015,14(10), 996-1001). In addition, Professor Zhao Zhigang, from the novel perspective of electrolyte modification, promoted the exchange of electrons with Al during the film fading process by adding a small amount of highly oxidizing H2O2 to the AlCl3 aqueous electrolyte in advance. 3+ The extraction of tungsten trioxide improves the transmittance and fading rate of the fading state and significantly increases the charge storage capacity of tungsten trioxide (Angew. Chem. Int. Ed. , 2016, 55(25), 7161-7165).

[0005] However, the voltage applied during the experiment was relatively high (typically 5.5–6.0 V vs. Li / Li). + The first problem is that the organic electrolyte decomposes and the conductive coating degrades, which can easily cause side reactions (Thin Solid Films, 2020, 697, 137830-137834). Secondly, aqueous solutions generally have a narrow stable voltage range, while the coloring reaction of tungsten trioxide films basically occurs below the hydrogen evolution potential. Therefore, the color change process is easily accompanied by side reactions such as hydrogen evolution, resulting in electrolyte loss and performance degradation. Finally, traditional alkali metal cation charge carriers generally have a serious "ion trapping" phenomenon in tungsten trioxide-based electrochromic devices (The Journal of Physical Chemistry C, 2018, 122(33), 19037-19043; Angew.Chem. Int. Ed. 2016, 128(21), 6352-6355), which significantly affects the cycle stability of the device and is not conducive to the construction of long-life electrochromic devices. Summary of the Invention

[0006] This invention addresses the shortcomings of existing technologies by providing an electrolyte for tungsten trioxide-based electrochromic devices. The technical problem this invention aims to solve is to address the challenges posed by traditional electrolytes, such as severe ion trapping, narrow stable voltage range, hydrogen / oxygen evolution side reactions, slow reaction kinetics, tungsten trioxide dissolution, and poor cycle stability. This invention develops a high-performance electrolyte for tungsten trioxide electrochromic devices. The electrolyte of this invention not only effectively alleviates the ion trapping effect and significantly improves the cycle stability of tungsten trioxide electrochromic devices, but also effectively expands the stable voltage range of the electrolyte, broadening the range of electrode materials that can be selected.

[0007] The specific technical solution is as follows:

[0008] The purpose of this invention is to provide an electrolyte for tungsten trioxide-based electrochromic devices, which differs from the prior art in that it includes an organic solvent and an electrolyte; the electrolyte includes an ammonium salt.

[0009] The electrolyte of this invention can be used to construct high-performance, long-life tungsten trioxide-based electrochromic devices. When the tungsten trioxide electrochromic electrode undergoes an electrochromic reaction, the electrolyte acts as an electrochemical reaction medium between the electrochromic electrode and the counter electrode, ensuring the electroneutrality of both electrodes by transporting the cations required for the electrochromic reaction. The electrolyte of this invention not only effectively overcomes the problems of traditional electrolytes, such as narrow stable voltage range, numerous side reactions, slow reaction rate, and short electrochromic cycle life, but also has significant advantages such as a wide applicable temperature range, high water and oxygen tolerance, simple preparation process, mild conditions, and suitability for industrial mass production.

[0010] Compared to metallic charge carriers, NH4 + Its small molar mass and solvation radius promote rapid diffusion in the electrolyte; its mild electrolyte environment results in less corrosion to electrode materials; NH4 + Charge carriers are abundant resources, which is more conducive to achieving sustainable energy development. Based on experimental results and literature review, we hypothesize that WO3 coatings in NH4... + The mechanism by which the electrolyte cycling stability is improved is because, compared to metal ions, non-metallic NH4+... + Ion transport in WO3 coatings occurs through the formation and breaking of hydrogen bonds.

[0011] Furthermore, the ammonium salt is NH4. + F - Cl - ,Br - I - BF4 - PF6 - AsF6 - SbF6 - ClO4 - NO3 - SO4 2- SCN - PO4 3- BC2O4 - BFC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - (CF3)2SO2N - (CF3CF2)2SO2N - F2SO2N - C4F9SO3 - C2O4 2- CF3SO3 - CF3CF2SO3 - (CF3SO2)2CH - CF3(CF2)7SO3 - CF3CF2(CF3)2CO - CF3CO2 - CH3CO2 - A mixture of one or more salts.

[0012] Further, the organic solvent is ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl carbonate, dioctyl carbonate, fluoroethylene carbonate, ethyl acetate, methyl butyrate, ethyl butyrate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, propyl propionate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl butyrate, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, dimethyl sulfoxide, sulfolane, acetonitrile, ethylene glycol, butadiene nitrile, o-methylbenzonitrile, o-tolueneacetonitrile, m-methylbenzonitrile, ethanol, propanol, butanol. One or more of the following: pentanol, hexanol, polyols, 2-methylglutaronitrile, 3-methoxypropionitrile, 3-ethoxypropionitrile, sebacate, 2,2,2-trifluoroethoxypropionitrile, glutaronitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methylphosphonate, diethyl ethylphosphonate, triisobutyl phosphate, triisopropylphenyl phosphate, tributyl phosphate, tripentyl phosphate, trioctyl phosphate, toluene diphenyl phosphate, ethyl phosphate, dimethyl phosphite, diethyl phosphite, trimethyl phosphite, triethyl phosphite, tributyl phosphite, trihexyl phosphite, and trioctyl phosphite.

[0013] Furthermore, the electrolyte may also include Li + Na + K + 、Rb + Cs + Ag + Ch + TAB + [C3mpyr] + [BuMePy] + [BMIM] + H + NH4 + Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ Ni 2+ Mn 2+ Cu 2+ Al 3+ Fe 3+ Er 3+ Eu 3+ Ti 4+ One or more cations with F - Cl - ,Br -I - BF4 - PF6 - AsF6 - SbF6 - ClO4 - NO3 - SO4 2- SCN - PO4 3- BC2O4 - BFC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - (CF3)2SO2N - (CF3CF2)2SO2N - F2SO2N - C4F9SO3 - C2O4 2- CF3SO3 - CF3CF2SO3 - (CF3SO2)2CH - CF3(CF2)7SO3 - CF3CF2(CF3)2CO - CF3CO2 - CH3CO2 - A salt composed of one or more anions. That is, the electrolyte of the present invention can be a combination of ammonium salt and metal salt.

[0014] Furthermore, the total concentration of the electrolyte in the electrolyte solution is 0.01~5.0 mol / L, more preferably 0.08~5.0 mol / L.

[0015] The concentration of ammonium salt in the electrolyte is 0.01~5.0 mol / L, more preferably 0.04~5.0 mol / L.

[0016] Furthermore, the electrolyte also includes a gelling agent and / or gelling components. By adding a gelling agent and / or gelling components to the electrolyte, the liquid state is transformed into a gel state.

[0017] The gelling agent is preferably one or more of the following: polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral, hydroxypropyl acrylate, hydroxypropyl methyl methacrylate, hydroxyethyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinylidene fluoride, polytetrafluoroethylene, chitosan, chondroitin, polyethylene glycol, polycyclopropane carbonate, polyethylene oxide, polyvinyl methyl ether, polyacrylamide fumarate, polylactic acid-hydroxyhexanoic acid, cellulose glue, cellulose ether, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxycellulose salt, sodium alginate, carrageenan, gellan gum, xanthan gum, gelatin, agar, and sodium silicate.

[0018] The gelling component is preferably one or more of the following: cumene hydroperoxide, azobisisobutyronitrile, tert-butyl hydroperoxide, tert-butyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, dopamine, aniline, poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) methyl ether methacrylate, poly(ethylene glycol) dimethacrylate, poly(ethylene glycol) diacrylate, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, and phenolic resin.

[0019] Furthermore, the organic solvent accounts for more than 15% of the volume in the electrolyte. Preferably, when the electrolyte contains at least one of a gelling agent and a gelling component, the total amount of the above components to the volume ratio of the organic solvent is 1:(0.2~4).

[0020] The present invention also discloses the application of the above-mentioned electrolyte in tungsten trioxide-based electrochromic devices.

[0021] Specifically, the tungsten trioxide-based electrochromic devices are applied in the fields of building energy-saving glass, aircraft dimming glare windows, optical stealth, anti-glare goggles, car sunroofs, photothermal management, smart homes, energy-saving displays, or flexible devices.

[0022] The beneficial effects of this invention are as follows:

[0023] (1) Compared to traditional metal cation electrolytes, the electrolyte described in this invention can significantly improve the cycle stability of tungsten trioxide electrochromic films. Tests show that in Li + In the electrolyte, the tungsten trioxide coating exhibits a significant decrease in color-changing performance after 300 cycles. However, in the electrolyte described in this invention, the tungsten trioxide coating retains very high color-changing performance even after 800 cycles.

[0024] (2) Compared with traditional metal cation electrolytes, the high-performance electrolyte of the present invention can significantly widen the stable voltage range from 2.3 ~ 3.4 V to 5.85 V. The wider stable voltage window not only expands the range of electrode materials but also suppresses various side reactions.

[0025] (3) Compared with traditional metal cation electrolytes, the high-performance electrolyte of the present invention has better antifreeze properties, which can effectively broaden the application scenarios of electrochromic devices. Attached Figure Description

[0026] Figure 1 A photograph of the FTO conductive glass and the color-changing electrode 1 (WO3 / FTO glass) prepared by the technical solution in the specific embodiment;

[0027] Figure 2 The diagram shows the structure of devices 1, 2, and 3 assembled in the specific embodiment; wherein: 1—substrate, 2—conductive layer, 3—tungsten trioxide color-changing electrode, 4—electrolyte, 5—device encapsulation material, 6—counter electrode, 7—substrate;

[0028] Figure 3 Linear sweep voltammetric curves of different electrolytes in test 1; where (a) electrolyte 1, (b) control electrolyte 1;

[0029] Figure 4 Cyclic voltammetry (CV) curves of the color-changing electrode 2 in different electrolytes were tested; where (a) electrolyte 1, (b) control electrolyte 1, and (c) control electrolyte 2.

[0030] Figure 5 The real-time transmittance change curves (wavelength 633 nm) of the color-changing electrode 3 in test 3 when switching colors in different electrolytes are shown; where (a) electrolyte 1, (b) control electrolyte 1, and (c) control electrolyte 2.

[0031] Figure 6 The color-changing response curves of the color-changing electrode 3 in 4 were tested when the color was switched in different electrolytes; where (a, b) are electrolyte 1 and (c, d) are control electrolyte 2.

[0032] Figure 7 To test the color-changing efficiency (CE) of the color-changing electrode 1 in 5 when switching colors in different electrolytes; where (a) electrolyte 1, (b) control electrolyte 1, and (c) control electrolyte 2. Detailed Implementation

[0033] The principles and features of the present invention are described below with reference to examples. The examples are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0034] For ease of discussion, in the following embodiments, the preparation of the tungsten trioxide electrochromic device is divided into three steps: 1. Preparation of tungsten trioxide electrochromic electrode; 2. Preparation of electrolyte; 3. Device assembly; the products obtained in each step are named according to the corresponding step number.

[0035] Step 1: Preparation of tungsten trioxide electrochromic electrode

[0036] Color-changing electrode 1:

[0037] 1.5 g of commercial nano-tungsten trioxide (WO3) powder and 8 mL of zirconium oxide (ZrO2) grinding balls were added to 30 mL of isopropanol solution and milled for 72 h to obtain a highly stable nano-WO3 dispersion with a solid content of 5 wt.%. FTO conductive glass was ultrasonically washed sequentially with deionized water, acetone, isopropanol, and deionized water, and then dried. The 5 wt.% nano-WO3 dispersion was then coated onto the FTO conductive glass using a drop-coating method. After the dispersion naturally leveled, the coated FTO conductive glass was first dried in a 60℃ oven, then heated to 200℃ at a heating rate of 6℃ / min and held at that temperature for 2 h. After naturally cooling to room temperature, a uniform, transparent, and well-adhesive tungsten trioxide coating was obtained.

[0038] The tungsten trioxide thin film was prepared by uniformly coating a nano-tungsten trioxide dispersion onto FTO conductive glass using a drop-coating method. Photos of the FTO conductive glass used for coating and the resulting color-changing electrode 1 are shown below. Figure 1 As shown. Figure 1 In the middle, WO3 / FTO glass is light yellow.

[0039] Color-changing electrode 2:

[0040] Using ITO conductive glass, Pt foil, and an Ag / AgCl electrode as the working, counter, and reference electrodes, respectively, and a hydrogen peroxide (H₂O₂) solution containing 1.8 g of W powder as the electrolyte, a WO₃ film was deposited on ITO glass using an electrodeposition method under three-electrode conditions. The deposition process preferably used a chronoamperometry method, employing a +0.3 / -0.3 V square wave voltage, with each voltage applied for 0.3 s, for 1000 cycles, to obtain a tungsten trioxide electrochromic film. This tungsten trioxide film was deposited on ITO conductive glass via electrodeposition.

[0041] Color-changing electrode 3:

[0042] WO3 thin films were deposited on ITO conductive glass using magnetron sputtering. The sputtering target was a 5 cm diameter tungsten sheet, and the substrate was ITO conductive glass. During sputtering, the conditions of an O2 / Ar gas flow ratio of 6:94, a target power of 70 W, and a gas pressure of 2 Pa were maintained for 30 min to obtain the color-changing electrode 3.

[0043] Step 2: Electrolyte preparation

[0044] Example 1

[0045] Electrolyte 1 with an NH4PF6 concentration of 0.5 mol / L was prepared by dissolving NH4PF6 in propylene carbonate (PC).

[0046] Example 2

[0047] Dissolve NH4NO3 in a mixed solution of acetonitrile (AN) and succinate (SN) (AN to SN volume ratio of 3:2) to prepare electrolyte 2 with a NH4NO3 concentration of 2.5 mol / L.

[0048] Example 3

[0049] Electrolytes 3 were prepared by dissolving NH4BF4 and LiClO4 in ethylene carbonate (EC) and preparing NH4BF4 and LiClO4 concentrations of 0.1 mol / L and 2 mol / L, respectively.

[0050] Example 4

[0051] Electrolytes 4 were prepared by dissolving NH4(CF3)2SO2N and K2SO4 in a mixed solution of dimethyl sulfoxide (DMSO) and diethyl ethyl phosphonate (DEEP) (DMSO to DEEP volume ratio of 1:4) to obtain electrolytes with concentrations of 4.5 mol / L for NH4(CF3)2SO2N and 0.05 mol / L for K2SO4.

[0052] Example 5

[0053] An electrolyte solution 5 was prepared by dissolving NH4BC2O4 and Zn(NO3)2 in an equimolar ratio in a mixed solution of propylene carbonate (PC) and N,N-dimethylformamide (DMF) (PC to DMF volume ratio of 2:3) to obtain an electrolyte solution with a concentration of 0.05 mol / L for both NH4BC2O4 and Zn(NO3)2.

[0054] Example 6

[0055] Dissolve NH4CF3CO2 and TBACl in a mixed solution of dimethyl carbonate (DMC) and N-methylpyrrolidone (NMP) (DMC and NMP volume ratio of 1:1) to prepare electrolyte 6 with a concentration of 1 mol / L for both NH4CF3CO2 and TBACl.

[0056] Example 7

[0057] Carboxymethyl cellulose and tetrahydrofuran (THF) were uniformly mixed at a volume ratio of 4:1. 0.25 mol / L NH4(CF3)5PF and 0.5 mol / L NaC4F9SO3 were added to the mixed solution. After stirring at room temperature for 12 hours, gel electrolyte 7 was obtained.

[0058] Example 8

[0059] Poly(ethylene glycol) methyl ether methacrylate and ethyl acetate (EA) were uniformly mixed at a volume ratio of 3.2:1.8. 20 mg / mL of azobisisobutyronitrile and 0.5 mol / L of NH4NO3 were added to the mixed solution. After stirring at 30°C for 3 hours, the resulting solution was placed in a 60°C oven for 3 hours to obtain gel electrolyte 8.

[0060] Comparative Example 1

[0061] Dissolve NH4PF6 in H2O to prepare a control electrolyte 1 with an NH4PF6 concentration of 0.5 mol / L.

[0062] Comparative Example 2

[0063] LiPF6 was dissolved in propylene carbonate (PC) to prepare a control electrolyte 2 with a LiPF6 concentration of 0.5 mol / L.

[0064] Step 3: Assembly of Tungsten Trioxide Electrochromic Device

[0065] A schematic diagram of the assembled components is shown below. Figure 2 As shown.

[0066] Device 1

[0067] A transparent Zn counter electrode is prepared by attaching a Zn strip to a transparent glass substrate (the area ratio of the Zn strip to the glass is 1:9). A color-changing electrode 2 is then bonded to the counter electrode using silicone to form a small cavity with a thickness of 5 mm. Subsequently, an electrolyte is injected between the color-changing electrode and the counter electrode using a syringe, thus completing the assembly of the electrochromic device.

[0068] Device 2

[0069] Using ITO conductive glass as the counter electrode, butyl rubber is used to bond the color-changing electrode 1 to the counter electrode to form a small groove with a 5 mm thick cavity. Subsequently, electrolyte is injected into the space between the color-changing electrode and the counter electrode using a syringe, thus completing the assembly of the electrochromic device.

[0070] Device 3

[0071] The counter electrode is an FTO conductive glass coated with PB. The color-changing electrode 3 is bonded to the counter electrode using epoxy resin to form a small groove with a 5 mm thick cavity. Then, electrolyte is injected between the color-changing electrode and the counter electrode using a syringe, thus completing the assembly of the electrochromic device.

[0072] Test 1

[0073] Linear potential scanning was performed on electrolyte 1 obtained in Example 1 and control electrolyte 1 obtained in Comparative Example 1 using linear sweep voltammetry. The obtained linear sweep voltammetric curves are shown below. Figure 3 As shown. Figure 3 In the middle, (a) electrolyte 1, (b) control electrolyte 1.

[0074] As can be seen from the above data, the stable voltage range of electrolyte 1 is 2.3 V (relative to silver / silver chloride), while the stable voltage range of the electrolyte disclosed in this invention is 5.85 V (relative to silver / silver chloride). A wider stable voltage window not only expands the range of electrode materials that can be selected, but also helps to suppress side reactions such as electrolyte decomposition.

[0075] Test 2

[0076] The color-changing electrode 2 was tested, and its cyclic voltammetry (CV) curves in different electrolytes were obtained, as follows: Figure 4 As shown. Figure 4 In the examples, (a) electrolyte 1 (Example 1), (b) comparative electrolyte 1, and (c) comparative electrolyte 2.

[0077] As can be seen from the above data, compared with electrolytes 1 and 2, the tungsten trioxide coating exhibits unique electrochemical reaction characteristics in electrolyte 1 of this invention, with its CV curve showing a lower polarization potential and a higher current density. Furthermore, the tungsten trioxide coating also exhibits excellent electrochemical stability in other electrolytes of this invention, such as electrolyte 3, whose CV curve retains 85% of its electrochemical activity after 500 cycles.

[0078] Test 3

[0079] The color-changing electrode 3 was tested, and its real-time transmittance change curve (wavelength 633 nm) was obtained when switching colors in different electrolytes. Figure 5 As shown. Figure 5In the examples, (a) electrolyte 1 (Example 1), (b) comparative electrolyte 1, and (c) comparative electrolyte 2.

[0080] The data above shows that in comparative electrolyte 1, the light modulation amplitude of the tungsten trioxide coating rapidly decreased from the initial 65.8% to completely disappear after 100 cycles. Even in comparative electrolyte 2, although the cycle life of the tungsten trioxide coating was effectively improved, its light modulation amplitude still rapidly decreased to 40.15% after 300 cycles, indicating a decline in the coating's color-changing performance. However, in electrolyte 1 of this invention, the color-changing performance of the tungsten trioxide coating remained stable after 800 cycles. In contrast, the tungsten trioxide coating maintained 90% of its light modulation amplitude after 1000 cycles in electrolyte 6 of this invention, further improving its cycle life.

[0081] Test 4

[0082] The color-changing electrode 3 was tested to obtain its color-changing response curves when switching colors in different electrolytes, such as... Figure 6 As shown. Figure 6 In the middle, (a, b) electrolyte 1 (Example 1), (c, d) comparative electrolyte 2.

[0083] It is worth noting that after long-term cycling, the fading time of the tungsten trioxide coating in electrolyte 1 decreased. The same phenomenon also appeared in electrolytes 2 and 5. Furthermore, after 1000 cycles in electrolyte 7, the coloring / fading time of the coating decreased significantly. In contrast, in electrolyte 2, the fading response time of the coating increased to approximately twice the initial time with increasing cycle count.

[0084] Test 5

[0085] The color-changing electrode 1 was tested to obtain its coloring efficiency (CE) when switching colors in different electrolytes, such as... Figure 7 As shown. Figure 7 In the examples, (a) electrolyte 1 (Example 1), (b) comparative electrolyte 1, and (c) comparative electrolyte 2.

[0086] As shown in the above data, the change in optical density (ΔOD) of the thin film increases with the increase of injected charge. By linearly fitting the optical density-charge density relationship curve, the CE values ​​of the tungsten trioxide coating in comparative electrolytes 1 and 2, and electrolyte 1 of this invention, can be calculated from the slope of the straight line. These values ​​are 85.29, 42.87, and 39.02 cm⁻¹, respectively. 2 C -1 Linear fitting revealed that the CE value of the coating in electrolyte 3 was 22.71 cm⁻¹. 2 C -1The greater the coloring efficiency, the greater the change in the material's light transmittance caused by a certain amount of charge.

[0087] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolyte for use in tungsten trioxide-based electrochromic devices, characterized in that, It includes organic solvents and electrolytes; the electrolytes include ammonium salts; The ammonium salt is NH4 + F - Cl - ,Br - I - BF4 - PF6 - AsF6 - SbF6 - ClO4 - NO3 - SO4 2- SCN - PO4 3- BC2O4 - BFC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - (CF3)2SO2N - (CF3CF2)2SO2N - F2SO2N - C4F9SO3 - C2O4 2- CF3SO3 - CF3CF2SO3 - (CF3SO2)2CH - CF3(CF2)7SO3 - CF3CF2(CF3)2CO - CF3CO2 - CH3CO2 - A mixture of one or more salts; The organic solvents mentioned are ethylene carbonate, propylene carbonate, butene carbonate, vinylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, dipropyl carbonate, dibutyl carbonate, dioctyl carbonate, fluoroethylene carbonate, ethyl acetate, methyl butyrate, ethyl butyrate, methyl formate, ethyl formate, propyl formate, butyl formate, methyl acetate, propyl propionate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl butyrate, dimethoxymethane, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, dimethyl sulfoxide, sulfolane, acetonitrile, ethylene glycol, butadiene nitrile, o-methylbenzonitrile, o-tolueneacetonitrile, m-methylbenzonitrile, ethanol, propanol, butanol, pentaethyl alcohol, etc. One or more of the following: alcohol, hexanol, polyol, 2-methylglutaronitrile, 3-methoxypropionitrile, 3-ethoxypropionitrile, sebacate, 2,2,2-trifluoroethoxypropionitrile, glutaronitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, tris(2,2,2-trifluoroethyl) phosphite, dimethyl methylphosphonate, diethyl ethylphosphonate, triisobutyl phosphate, triisopropylphenyl phosphate, tributyl phosphate, tripentyl phosphate, trioctyl phosphate, toluene diphenyl phosphate, ethyl phosphate, dimethyl phosphite, diethyl phosphite, trimethyl phosphite, triethyl phosphite, tributyl phosphite, trihexyl phosphite, and trioctyl phosphite.

2. The electrolyte according to claim 1, characterized in that, The electrolyte also includes Li + Na + K + 、Rb + Cs + Ag + TAB + [C3mpyr] + [BuMePy] + [BMIM] + H + NH4 + Be 2+ Mg 2+ Ca 2+ 、Sr 2+ Ba 2+ Zn 2+ Ni 2+ Mn 2 + Cu 2+ Al 3+ Fe 3+ Er 3+ Eu 3+ Ti 4+ One or more cations with F - Cl - ,Br - I - BF4 - PF6 - AsF6 - SbF6 - ClO4 - NO3 - SO4 2- SCN - PO4 3- BC2O4 - BFC4O8 - (CF3)2PF4 - (CF3)3PF3 - (CF3)4PF2 - (CF3)5PF - (CF3)6P - (CF3)2SO2N - (CF3CF2)2SO2N - F2SO2N - C4F9SO3 - C2O4 2- CF3SO3 - CF3CF2SO3 - (CF3SO2)2CH - CF3(CF2)7SO3 - CF3CF2(CF3)2CO - CF3CO2 - CH3CO2 - A salt composed of one or more anions.

3. The electrolyte according to claim 1, characterized in that, The total concentration of the electrolyte in the electrolyte solution is 0.01~5.0 mol / L.

4. The electrolyte according to claim 1, characterized in that, It also includes gelling agents and / or gelling components.

5. The electrolyte according to claim 4, characterized in that, The gelling agent is one or more of the following: polyvinylpyrrolidone, polyvinyl alcohol, polyvinyl butyral, hydroxypropyl acrylate, polymethyl methacrylate, polyacrylamide, polyvinylidene fluoride, polytetrafluoroethylene, chitosan, chondroitin, polyethylene glycol, polycyclopropane carbonate, polyethylene oxide, polyvinyl methyl ether, polyacrylamide fumarate, polylactic acid-hydroxyhexanoic acid, cellulose glue, cellulose ether, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, carboxycellulose salt, sodium alginate, carrageenan, gellan gum, xanthan gum, gelatin, agar, and sodium silicate.

6. The electrolyte according to claim 4, characterized in that, The gelling component is one or more of the following: cumene hydroperoxide, azobisisobutyronitrile, tert-butyl hydroperoxide, tert-butyl peroxide, methyl ethyl ketone peroxide, cyclohexanone peroxide, dicumyl peroxide, dopamine, aniline, poly(ethylene glycol) methyl ether acrylate, poly(ethylene glycol) methyl ether methacrylate, poly(ethylene glycol) dimethacrylate, poly(ethylene glycol) diacrylate, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, and phenolic resin.

7. The application of the electrolyte as described in any one of claims 1 to 6 in a tungsten trioxide-based electrochromic device.

8. The application according to claim 7, characterized in that, The tungsten trioxide-based electrochromic devices described herein are applied in fields such as building energy-saving glass, aircraft dimming glare windows, optical stealth, anti-glare goggles, car sunroofs, photothermal management, smart homes, energy-saving displays, or flexible devices.

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