Conductive polymer electrochromic thin film electrode and preparation thereof

Abstract

The application provides a conductive polymer electrochromic thin film electrode and preparation thereof, in particular, a precursor electrolyte, which comprises pyrrole (Py), benzothiadiazole ethyl acetate (BTH), K2HPO4, sodium p-toluenesulfonate (TSONa) and NaF, and the pH value of the precursor electrolyte is 0-3; the electrochromic thin film prepared by using the precursor electrolyte has greatly improved cycle stability.

Description

Technical Field

[0001] This invention relates to the field of electrodes, and more specifically, to a conductive polymer electrochromic thin film electrode and its preparation. Background Technology

[0002] Electrochromism refers to the reversible and stable change in a material's optical properties—including light transmission, reflection, and absorption—under the influence of an applied electric field, macroscopically manifested as a reversible change in color. Conductive polymer materials can persistently and stably maintain their color change after the voltage is removed, making electrochromic devices more energy-efficient and ensuring the maintenance of their optical properties without consuming electrical energy. Electrochromic technology can dynamically control the transmittance of visible and near-infrared light, showing promising applications in areas such as energy-efficient smart windows in buildings, flexible electronic display devices, and adaptive camouflage.

[0003] Electrochromic devices based on conductive polymers mainly consist of three parts: a working electrode, an electrolyte, and a counter electrode. The electrochromic layer, called the working electrode, is the core layer and the layer where the color-changing reaction occurs. This layer mainly appears in the form of an electrochromic thin film. Compared with inorganic electrochromic materials based on transition metal oxides, conductive polymer materials have advantages such as rich colors, low voltage driving, fast response speed, and ease of molecular structure design. Polypyrrole (PPy), as an electron-rich polymer material, undergoes color changes due to intramolecular electron transfer, specifically including three different states: neutral state, cationic oxidized state, and anionic reduced state, each displaying different colors. The oxidized state is the stable state of polypyrrole, where there is no photocharge transfer caused by anions. When subjected to a negative voltage, the organic polypyrrole first gains one electron, initiating reduction and coloring; after gaining two electrons, the polypyrrole is completely reduced, displaying another color. Research has found that the color of polypyrrole organic compounds is also related to the type of substituents. By modifying the nitrogen (N) position and the 3, 4 carbon (C) position of polypyrrole, a variety of colors can be obtained, and a rich color range will help expand the application range of polypyrrole organic compounds.

[0004] Currently, polypyrrole and its derivatives possess advantages such as good conductivity, high optical contrast, and good color reversibility. However, in traditional film-forming processes, the poor solubility of polypyrrole and its derivatives affects the subsequent film-forming effect, leading to a decrease in the stability of the prepared electrochromic films. Therefore, it is necessary to develop a simple and environmentally friendly electrochemical film-forming method to solve the problem of difficult film formation of polypyrrole and its derivatives, thereby improving the periodic stability of electrochromic films. Summary of the Invention

[0005] The present invention aims to solve one of the problems in the prior art. Specifically, the present invention proposes a new precursor electrolyte and an electrochromic film prepared using the precursor electrolyte. The method is green and environmentally friendly, solves the problem of difficult film formation of polypyrrole and its derivatives, and greatly improves the periodic stability of the obtained electrochromic film.

[0006] In one aspect of the invention, a precursor electrolyte is provided. According to an embodiment of the invention, the precursor electrolyte comprises: pyrrole (Py), ethyl benzothiadiazole (BTH), K2HPO4, sodium p-toluenesulfonate (TSONa), and NaF, and the pH value of the precursor electrolyte is 0-3.

[0007] According to embodiments of the present invention, the precursor electrolyte may further include at least one of the following additional technical features: According to an embodiment of the present invention, the concentration of the pyrrole is 0.05~0.50 mol L. -1 The concentration of ethyl benzothiadiazole is 0.002~0.05 mol / L. -1 The concentration of K2HPO4 is 0.02~0.50 mol L. -1 The concentration of the sodium p-toluenesulfonate is 0.02~0.50 mol / L. -1 The concentration of NaF is 0.008~0.3 mol L. -1 .

[0008] According to an embodiment of the present invention, the pH value of the precursor electrolyte is 0-1.

[0009] In another aspect, the present invention also provides a method for preparing an electrochromic thin-film electrode. According to an embodiment of the present invention, the method includes: S1: Provide an anode substrate and place it in a precursor electrolyte, the precursor electrolyte comprising pyrrole, ethyl benzothiadiazole, K2HPO4, sodium p-toluenesulfonate and NaF, the pH of the precursor electrolyte being 0~3; S2: PPy-BTH nanofilm conductive polymer is generated on the anode substrate by electrochemical polymerization using a one-step chronoamperotropic deposition mode, yielding the electrochromic thin film electrode. This method is simple to operate, operates under mild conditions, and allows for rapid polymerization and deposition. It offers good controllability over the morphology and conductivity of the product film; the film exhibits good uniformity, is free of surface surfactants, and demonstrates good lattice matching between the polymer film material and the substrate. It also boasts good repeatability and low cost, making it particularly suitable for use as an anode material in electrochromic devices.

[0010] In this invention, the influence of the BTH group on polypyrrole is manifested in two aspects: firstly, it directly participates in the electrochemical polymerization process of polypyrrole; secondly, it is doped into conductive polypyrrole in the form of anions, thereby affecting the conductivity of the polypyrrole film through interaction with the oxidized polypyrrole backbone. Furthermore, BTH has a weak nucleophilicity and cannot restrain the positive charge on the polypyrrole backbone, thus promoting efficient charge transport and delocalizing electrons throughout the backbone, endowing polypyrrole with unique electronic conductivity and also improving its mechanical properties. BTH has a medium-sized molecular structure with moderate steric hindrance; its stereoshik effect can significantly enhance the stability of specific chemical bonds, preventing decomposition or side reactions caused by intermolecular collisions, which is beneficial for increasing the density of states of polypyrrole and enhancing the interaction between molecular chains, thus improving the stability of polypyrrole derivatives. These characteristics give polypyrrole derivative films advantages for electrochromic applications.

[0011] Of course, the present invention can also adjust the morphology and conductivity of the PPy derivative nanofilm layer deposited on the anode by controlling the type of anion (anionic groups doped in the conjugated backbone of the PPy derivative polymer) in the electrolyte. For example, when the anion is adjusted to TSO... - At this time, the conductivity of the PPy-TSO-F thin film can be controlled at 10¹¹ S cm⁻¹. -1 When the anion is adjusted to BTH, the conductivity of the PPy-BTH film can be controlled at 715 S cm. -1 When the anion is adjusted to ClO4 - At this time, the conductivity of PPy-ClO4 can be controlled at 120 S cm⁻¹. -1 The ClO4 group has a limited effect on regulating the conductivity of PPy films, resulting in poor electrochromic properties; the TSO group has a very prominent effect on regulating the conductivity of PPy films, resulting in good electrochromic properties, but its electrochromic stability is very poor; while the BTH group has a moderate effect on regulating the conductivity of PPy films, thus giving them both excellent electrochromic properties and stability.

[0012] According to embodiments of the present invention, the above method may further include at least one of the following additional technical features: According to an embodiment of the present invention, the concentration of the pyrrole is 0.05~0.50 mol L. -1 The concentration of ethyl benzothiadiazole is 0.002~0.05 mol / L. -1 The concentration of K2HPO4 is 0.02~0.50 mol L. -1 The concentration of the sodium p-toluenesulfonate is 0.02~0.50 mol / L. -1The concentration of NaF is 0.008~0.3 mol L. -1 .

[0013] According to an embodiment of the present invention, the pH value of the precursor electrolyte is 0-1.

[0014] According to an embodiment of the present invention, during the electrochemical polymerization reaction, the potential is kept constant at 0.05~5 V vs. SCE; the time is 5~180 s; and the current is maintained at 0.5 mA cm⁻¹. -2 ~10 mA cm -2 In this invention, applying a constant voltage (e.g., 0.65 V vs. SCE) to the anode optimizes the reaction kinetics in electrochemical deposition; F - It can alter the thermodynamics of the deposition process, promoting the electrochemical polymerization of pyrrole monomers; F - Adsorption on the electrode surface can change the charge density of the surface double layer, inhibiting the growth of some crystals and affecting the deposition kinetics. The p-toluenesulfonic acid group, as a surfactant anion, can reduce the interfacial tension between the aqueous solution and the polypyrrole film. It is easily adsorbed on the anode of the polypyrrole film, thereby preventing the interaction between the affinity water molecules and the polypyrrole molecular chains to form defect structures.

[0015] According to an embodiment of the present invention, during the electrochemical polymerization reaction, the potential is constantly set to 0.2~3 V vs. SCE.

[0016] According to an embodiment of the present invention, the electrochemical polymerization reaction takes 10 to 90 seconds.

[0017] According to an embodiment of the present invention, during the electrochemical polymerization reaction, the current is maintained at 1 mA cm⁻¹. -2 ~4 mAcm -2 .

[0018] According to an embodiment of the present invention, during the electrochemical polymerization reaction, the temperature of the precursor electrolyte is kept constant at 10°C. C ~50 C.

[0019] According to an embodiment of the present invention, during the electrochemical polymerization reaction, the temperature of the precursor electrolyte is kept constant at 18~30°C. C.

[0020] According to an embodiment of the present invention, step S1 further includes providing a cathode in the precursor electrolyte, wherein the cathode is spaced 1.5 to 6 cm from the anode substrate.

[0021] According to an embodiment of the present invention, step S1 further includes providing a cathode in the precursor electrolyte, wherein the cathode is spaced 2 to 4 cm from the anode substrate.

[0022] According to embodiments of the present invention, the anode substrate can be a glass substrate material coated with a transparent conductive oxide, including antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), molybdenum-doped indium oxide (IMO), aluminum-doped zinc oxide (AZO), and calcium-doped zinc oxide (GZO), preferably antimony-doped tin oxide (ATO), fluorine-doped tin oxide (FTO), and tin-doped indium oxide (ITO), and more preferably indium tin oxide (ITO).

[0023] According to an embodiment of the present invention, the anode substrate is provided by ITO.

[0024] According to an embodiment of the present invention, the precursor electrolyte is a nitrogen-saturated solution. A nitrogen-saturated electrolyte can eliminate the influence of dissolved oxygen on electrochemical polymerization deposition.

[0025] According to embodiments of the present invention, the electrolyte is preferably kept stationary throughout the electrochemical polymerization reaction or deposition process, i.e., without any stirring.

[0026] According to an embodiment of the present invention, the electrode is a uniform and smooth polypyrrole derivative nanofilm grown in situ on an ITO substrate using a one-step chronoamperometry deposition technique, thereby obtaining a reliable electrochromic electrode.

[0027] In another aspect, the present invention also provides an electrochromic thin-film electrode. According to an embodiment of the present invention, the electrochromic thin-film electrode is prepared according to the method described above.

[0028] According to embodiments of the present invention, the present invention also has the following features: The thickness and uniformity of the electrochromic film were effectively controlled by adjusting the applied voltage and deposition time. In a single aqueous solvent system, the conductivity of the nanostructure of polypyrrole derivatives can be controlled by adjusting only the type of anion, and the product has uniform distribution and high phase purity. It overcomes the limitations of traditional thermal synthesis methods, such as the constraints of high-temperature and high-pressure reaction conditions, the difficulty in completely removing reaction solvents, and the difficulties in film formation caused by poor monomer solubility, as well as the limitations in precise control of polymer material growth.

[0029] In summary, the one-step chronoamperometry deposition process used in this invention is simple, has mild conditions, and allows for rapid polymerization deposition. It offers good controllability over the morphology and conductivity of the product film, good film uniformity, no surfactants on the surface, good lattice matching between the polymer film material and the substrate, good repeatability, and low cost. It is particularly suitable for use as an anode material in electrochromic devices. Attached Figure Description

[0030] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 These are chronocurrent curves recorded during the polymerization and deposition process of PPy-BTH nanofilms according to Example 1 of the present invention. Figure 2a and Figure 2b The images are scanning electron microscope (SEM) images and grazing incidence X-ray scattering (XRS) spectra of the PPy-BTH nanofilms on the electrodes prepared according to Example 1 of the present invention. Figure 3a , Figure 3b and Figure 3c The images are scanning electron microscope (SEM) images, high-magnification transmission electron microscope (TEM) images, and atomic force microscope (AFM) images of the PPy-TSO-F nanofilms on the electrodes prepared according to Comparative Example 2. Figures 4a-4d The images shown are low-magnification scanning electron microscope (SEM) images, medium-magnification scanning electron microscope (SEM) images, high-magnification scanning electron microscope (SEM) images, and energy-scattered X-ray spectra of the PPy-ClO4 nanofilms on the electrodes prepared according to Comparative Example 4. Figure 5 This is the Raman spectrum of the PPy-BTH nanofilm on the electrode prepared according to Example 1 of the present invention after undergoing electrochromic color change reaction under different applied voltages; Figure 6a These are comparison graphs showing the conductivity of the nanofilms on electrodes prepared according to Example 1 and Comparative Example 2 of the present invention, respectively. Figure 6b The graphs show a comparison of the conductivity of the nanofilms on the electrodes prepared according to Comparative Example 2 and Comparative Example 3, respectively. Figures 7a-7d The figures shown are the electrochromic properties of the conductive polymer PPy-BTH nanofilm in 1 M LiClO4 medium in Example 1 of this invention. Figure 7a These are digital photographs showing color changes under different voltages; Figure 7b It is a cyclic voltammetry chart; Figure 7c It is the color-to-fade switching response under different potential steps; Figure 7d It is the long-cycle stability under different potential steps; Figure 8a and Figure 8bThe figures show the electrochromic properties of the PPy-TSO-F nanofilm on the electrode prepared in Comparative Example 2 in 1 M LiClO4 medium. Figure 8a These are digital photographs showing color changes under different voltages; Figure 8b It is the long-cycle stability under different potential steps; and Figure 9 The image shows the electrochromic properties of the PPy-ClO4 nanofilm on the electrode prepared in Comparative Example 4 in 1 M LiClO4 medium. Detailed Implementation

[0031] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0032] One-step fabrication of PPy derivative nanofilm electrochromic electrodes using chronocurrent rapid deposition mode Example 1 (1) The ITO substrate is pretreated and cut to a size of 1 × 2 cm. 2 First, it was ultrasonically cleaned in 20 mL of anhydrous acetone for 30 min, then ultrasonically treated with 20 mL of anhydrous ethanol and 20 mL of deionized water for 30 min respectively, and finally dried in a low-flow-rate nitrogen stream.

[0033] (2) The standard three-electrode system of the Chenhua electrochemical workstation (CHI760D) was adopted. The ITO sheet, platinum wire electrode, and saturated calomel (3 M KCl) electrode were used as the working electrode (anode), counter electrode (cathode), and reference electrode, respectively. The distance between the substrate ITO sheet and the counter electrode was adjusted to 3 cm, and the area of ​​ITO sheet immersed in the electrolyte was maintained at 1 cm. 1 cm 2 .

[0034] (3) Prepare a precursor electrolyte saturated with nitrogen for electrodeposition, providing 0.15 mol L of the electrolyte. -1 Pyrrole (Py), 0.01 mol L -1 ethyl benzothiadiazole (BTH), 0.10 mol L -1 K2HPO4, 0.10 mol L -1 Sodium p-toluenesulfonate (TSONa) and 0.05 mol L -1 A mixed solution of NaF was prepared, with the pH adjusted to approximately 0.5 using HCl, and the temperature kept constant at 25°C. C, The electrolyte remains stationary throughout the deposition process.

[0035] (4) Using the one-step chronocurrent electrodynamic deposition mode, the electrochemical deposition parameters were adjusted, the constant voltage was set to 0.65 V vs. SCE, and the deposition time was controlled to 20 s. Then, the PPy-BTH nanofilm was deposited on the ITO substrate to form a uniform and smooth gray-black film. Figure 1 It is its chronocurrent deposition curve; by Figure 1 It can be seen that by applying a relatively low voltage of 0.65 V vs. SCE to the anode, pyrrole (Py) monomers can be uniformly deposited on the ITO substrate under the influence of an electric field, and the resulting anodic current is maintained at 3.5 mA cm⁻¹. -2 about.

[0036] (5) Drop deionized water onto the surface of the electrode film formed by electrodeposition, let it stand for 2 minutes, and place absorbent paper at the bottom of the electrode film to absorb the deionized water film on the surface of the film. This process can be repeated 6 times. Then, place the film electrode in the air to air dry naturally for 1 hour to obtain the final product. Figure 2a and Figure 2b These are, respectively, the scanning electron microscope (SEM) image and the grazing incidence X-ray scattering spectrum of the obtained PPy-BTH nanofilm; Figure 2a and Figure 2b It is known that the PPy-BTH nanofilm has a dense structure, with nanospheres of 100-300 nm in diameter dispersed at a certain density, and has a mixed crystal type of crystalline-amorphous, with the (111) crystal plane being the main exposed crystal plane. The PPy-BTH nanofilm is uniformly deposited on the ITO substrate, thus forming an electrochromic electrode, and its smooth surface has a certain metallic luster. The average thickness of the nanofilm is 200 nm, and the roughness is 3.4 nm.

[0037] (6) After the PPy-BTH thin film electrode was dried, it was placed in 1 M LiClO4 (PC) medium for subsequent electrochromic electrochemical and spectroscopic tests. Figure 5 This is the Raman spectrum of the PPy-BTH nanofilm after undergoing electrochromic reactions under different applied voltages. Figures 7a-7d The following are the electrochromic properties of the PPy-BTH nanofilm: Figure 7a These are digital photographs showing color changes under different voltages; Figure 7b It is a cyclic voltammetry chart; Figure 7c It is the color-to-fade switching response under different potential steps; Figure 7d It refers to the long-cycle stability under different potential steps. Figure 5 It can be seen that the C=C bonds of the PPy-BTH polymer undergo subtle changes under different voltages. Figures 7a-7dIt can be seen that the PPy-BTH film follows a rich color change trend during cyclic voltammetry scanning within a potential window of -1.5 V to 0.75 V: bright yellow (-1.0 V), yellow-green (-0.5 V), gray (-0.1 V), red (0.3 V), and blue (0.5 V). When a potential step is made between -0.3 V and 0.1 V, a rapid color-changing / fading reaction occurs, with times of 0.7 s and 0.2 s, respectively. The PPy-BTH film has excellent cycling stability, and after 9200 continuous cycles, the electrochromic performance does not show significant decay.

[0038] Comparative Example 2 Steps (1)-(2) are exactly the same as in Example 1, and step (3) is the same as in Example 1 except that it does not contain BTH; (4) Using the one-step chronocurrent electrodynamic deposition mode, the electrochemical deposition parameters were adjusted, the constant voltage was set to 0.75 V vs. SCE, and the deposition time was controlled to 20 s. Then, the PPy-TSO-F nanofilm was deposited on the ITO substrate to form a uniform and smooth gray-black film.

[0039] (5) Drop deionized water onto the surface of the electrodeposited PPy-TSO-F thin film, let it stand for 1 min, and place absorbent paper under the electrode film to absorb the deionized water film on the film surface. This process can be repeated 3 times. Then, place the thin film electrode in the air to air dry naturally for 30 min to obtain the final product. Figure 3a , Figure 3b and Figure 3c These are scanning electron microscope (SEM) images, high-magnification transmission electron microscope (TEM) images, and atomic force microscope (AFM) images of the PPy-TSO-F nanofilm; from Figures 3a-3c It can be seen that the PPy-TSO-F nanofilm is uniformly deposited on the ITO substrate, forming an electrochromic electrode, and its surface is very smooth and dense with a certain metallic luster; it has a regular single crystal structure; the average thickness of the nanofilm is 110 nm and the roughness is 3.6 nm. Figure 6a This is a comparison of the conductivity of PPy-BTH and PPy-TSO-F nanofilms on electrodes prepared according to Example 1 and Comparative Example 2, respectively; Figure 6a It can be seen that PPy-TSO-F films all have high electrical conductivity, that is, they have good charge transport capabilities.

[0040] (6) After the PPy-TSO-F thin film electrode was dried, it was placed in a 1 M LiClO4 (PC) medium at room temperature for subsequent electrochromic electrochemical tests. Figure 8a This is an electrochromic image of the PPy-TSO-F nanofilm on the electrode prepared in Comparative Example 2; Figure 8bIt refers to the long-cycle stability under different potential steps. Figure 8a -b indicates that PPy-TSO-F films can also produce relatively rich color changes, and under the same voltage, the difference in their electrochromic response depends on the thickness of the film; PPy-TSO-F films have poor cycling stability, and after 9200 cycles (25000 s) of continuous long cycling, the electrochromic performance shows a significant decay.

[0041] Comparative Example 3 Steps (1) and (2) are exactly the same as in Example 1, except that the concentration of TSONa is changed to 0.05 mol / L in step (3). -1 Other examples are in the same proportion 2; (4) Using the one-step chronoamperodynamic deposition mode, the electrochemical deposition parameters were adjusted, the constant voltage was set to 0.75 V vs. SCE, and the deposition time was controlled to 50 s. Then, the PPy-TSO-1 nanofilm was deposited on the ITO substrate to form a uniform black film.

[0042] (5) Deionized water is dropped onto the surface of the electrodeposited PPy-TSO-1 thin film and left to stand for 1 min. Absorbent paper is placed under the electrode film to absorb the deionized water film on the surface. This process can be repeated 3 times. The thin film electrode is then allowed to air dry naturally for 30 min to obtain the final product. The PPy-TSO-1 nanofilm is uniformly deposited on the ITO substrate, thus forming an electrochromic electrode. Figure 6b This is a comparison of the conductivity of PPy-TSO-F and PPy-TSO-1 nanofilms on electrodes prepared according to Comparative Examples 2 and 3, respectively; Figure 6b It is known that the low TSO doping content in the PPy-TSO-1 nanofilm causes a decrease in its electrical conductivity. The low electrical conductivity results in a less prominent electrochromic effect of the PPy-TSO-1 thin film electrode, with low color saturation and a slow color application / fading response speed.

[0043] Comparative Example 4 Steps (1)-(2) are exactly the same as in Example 1.

[0044] (3) Prepare a precursor electrolyte saturated with nitrogen for electrodeposition, providing 0.15 mol L of the electrolyte. -1 Py, 0.05 mol L -1 HClO4, 0.10 mol L -1 K2HPO4 and 0.05 mol L -1 LiOH A mixed solution of H2O, at a constant temperature of 25°C. C, The electrolyte remains stationary throughout the deposition process.

[0045] (4) Using the one-step chronocurrent electrodynamic deposition mode, the electrochemical deposition parameters were adjusted, the constant voltage was set to 0.75 V vs. SCE, and the deposition time was controlled to 20 s. Then, the PPy-ClO4 nanofilm was deposited on the ITO substrate to form a gray film.

[0046] (5) Deionized water is dropped onto the surface of the electrode film formed by electrodeposition, and left to stand for 2 min. Absorbent paper is placed under the electrode film to absorb the deionized water film on its surface. This process can be repeated 3 times. The film electrode is then allowed to air dry naturally for 30 min to obtain the final product. A PPy-ClO4 nanofilm is uniformly deposited on an ITO substrate to form an electrochromic electrode, wherein the average thickness of the nanofilm is 150 nm.

[0047] Figures 4a-4d These are low-magnification, medium-magnification, and high-magnification scanning electron microscope (SEM) images of the PPy-ClO4 nanofilm, along with its energy-scattered X-ray spectrum. Figures 4a-4d It can be seen that the PPy-ClO4 film has a nanoflower-like microstructure and the elements contained therein are uniformly distributed.

[0048] (6) After the PPy-ClO4 thin film electrode was dried, it was placed in a 1 M LiClO4 (PC) medium at room temperature for subsequent electrochromic electrochemical tests. Figure 9 This is the electrochromic image of the PPy-ClO4 nanofilm on the electrode prepared in Comparative Example 4; by Figure 9 It can be seen that the electrochromic phenomenon of the thin film is not obvious, the color is monotonous, and the electrochromic kinetics are slow.

[0049] One-step fabrication of PPy-BTH-1 nanofilm electrochromic electrode using cyclic voltammetry electrodynamic slow deposition mode Comparative Example 5 Steps (1)-(3) are exactly the same as in Example 1.

[0050] (4) The slow deposition mode of cyclic voltammetry electrodynamics was adopted, and the electrochemical deposition parameters were adjusted. The potential window was set to -0.9 to 0.7 V, the number of scan segments was 5, and the scan rate was controlled at 5 mV s. -1 Then, PPy-BTH-1 nanofilms are deposited on the ITO substrate, forming an uneven black film.

[0051] (5) Deionized water is dropped onto the surface of the electrode film formed by electrodeposition, and left to stand for 3 min. Absorbent paper is placed under the electrode film to absorb the deionized water film on the film surface. This process can be repeated 6 times. The film electrode is then allowed to air dry naturally for 1 h to obtain the final product. PPy-BTH-1 nanofilms are deposited on ITO substrates to form electrochromic electrodes. However, the adhesion of PPy-BTH-1 nanofilms on ITO substrates is weak, and they are prone to breakage, affecting subsequent electrochromic performance testing.

[0052] One-step fabrication of PPy-BTH-2 nanofilm electrochromic electrodes using chronopotential rapid deposition mode Comparative Example 6 Steps (1)-(3) are exactly the same as in Example 1.

[0053] (4) A one-step chronopotential electrodynamic deposition mode was adopted, and the electrochemical deposition parameters were adjusted. The constant current was set to 3 mA cm⁻¹. -2 If the deposition time is controlled at 30 s, the PPy-BTH-2 nanofilm is deposited on the ITO substrate, forming a uniform light blue film.

[0054] (5) Deionized water is dropped onto the surface of the electrode film formed by electrodeposition, and left to stand for 2 minutes. Absorbent paper is placed under the electrode film to absorb the deionized water film on its surface. This process can be repeated 6 times. The film electrode is then allowed to air dry naturally for 1 hour to obtain the final product. The PPy-BTH-2 nanofilm is uniformly deposited on the ITO substrate, forming an electrochromic electrode. The PPy-BTH-2 nanofilm generated by this method is very easy to detach from the ITO substrate, which is detrimental to subsequent electrochromic stability testing.

[0055] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0056] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A precursor electrolyte, characterized in that, include: The precursor electrolyte contains pyrrole, ethyl benzothiadiazole, K2HPO4, sodium p-toluenesulfonate, and NaF, and has a pH of 0 to 3.

2. The precursor electrolyte according to claim 1, characterized in that, The concentration of the pyrrole is 0.05~0.50 mol / L. -1 The concentration of ethyl benzothiadiazole is 0.002~0.05 mol / L. -1 The concentration of K2HPO4 is 0.02~0.50 mol L. -1 The concentration of the sodium p-toluenesulfonate is 0.02~0.50 mol / L. -1 The concentration of NaF is 0.008~0.3 mol L. -1 .

3. A method for preparing an electrochromic thin-film electrode, characterized in that, include: S1: Provide an anode substrate and place it in a precursor electrolyte, the precursor electrolyte comprising pyrrole, ethyl benzothiadiazole, K2HPO4, sodium p-toluenesulfonate and NaF, the pH of the precursor electrolyte being 0~3; S2: PPy-BTH nanofilm conductive polymer is generated on the anode substrate by electrochemical polymerization reaction using a one-step time-current electrodynamic deposition mode to obtain the electrochromic thin film electrode.

4. The method according to claim 3, characterized in that, The concentration of the pyrrole is 0.05~0.50 mol L. -1 The concentration of ethyl benzothiadiazole is 0.002~0.05 mol / L. -1 The concentration of K2HPO4 is 0.02~0.50 mol / L. -1 The concentration of the sodium p-toluenesulfonate is 0.02~0.50 mol / L. -1 The concentration of NaF is 0.008~0.3 mol L. -1 .

5. The method according to claim 3, characterized in that, During the electrochemical polymerization reaction, the potential was kept constant at 0.05–5 V vs. SCE; the time was 5–180 s; and the current was maintained at 0.5 mA cm⁻¹. -2 ~10 mA cm -2 .

6. The method according to claim 3, characterized in that, During the electrochemical polymerization reaction, the temperature of the precursor electrolyte is kept constant at 10°C. C ~50 C.

7. The method according to claim 3, characterized in that, Step S1 further includes providing a cathode in the precursor electrolyte, with a distance of 1.5-6 cm between the cathode and the anode substrate.

8. The method according to claim 3, characterized in that, The anode substrate is made of ITO.

9. The method according to claim 3, characterized in that, The precursor electrolyte is a nitrogen-saturated solution.

10. An electrochromic thin-film electrode, characterized in that, The electrochromic thin film electrode is prepared by the method according to any one of claims 3-9.

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