Electrochromic material and preparation method thereof
By grafting a polymer matrix onto an electrochromic material to form a gel-like structure, the problem of easy dissolution of electrochromic materials in liquid electrolytes was solved, and the stability and uniformity of the material were achieved.
Patent Information
- Application Number
- CN202511716616.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-21
- Publication Date
- 2026-02-27
AI Technical Summary
Electrochromic materials are prone to chemical reactions or dissolution with electrolytes in liquid electrolyte environments, leading to structural damage and performance degradation, as well as uneven color changes.
The polymer matrix (such as polyvinyl alcohol, polymethyl methacrylate, polyurethane) is grafted with cathode and anode electrochromic materials (such as lithium-ion doped tungsten oxide, lithium-doped molybdenum oxide, polypyrrole, chromium-doped nickel oxide, lithium-doped nickel oxide, polythiophene). A gel structure is formed through stirring and curing. The pH value and temperature are controlled, and residual ions and impurities are removed by washing.
This improves the stability and performance of electrochromic materials, ensuring long-term stability and uniformity, and preventing material structure damage and performance degradation.
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of electrochromic materials, in particular to an electrochromic material and a preparation method thereof. BACKGROUND
[0002] Electrochromic materials are a class of special materials that can change color or transparency under the action of an external electric field or current. These materials include electrolyte sols (such as tungsten oxide), organic polymer films (such as polythiophene), and inorganic conductive oxide films (such as vanadium dioxide), which achieve the adjustment of optical properties through electric field-induced charge transfer or lattice structure changes, and are widely used in smart windows, electronic display devices, and other technical fields.
[0003] In a liquid electrolyte environment, electrochromic materials may directly chemically react or dissolve with the electrolyte, especially for some materials with low chemical stability, which can cause structural damage and performance degradation of the materials, making it difficult for them to work stably for a long time. Electrochromic materials that have not been gelatinized may exhibit uneven color change in the electrolyte, which may be due to local reaction differences caused by direct contact between the material surface and the electrolyte, resulting in inconsistent or unstable color changes. SUMMARY
[0004] To overcome the above-mentioned shortcomings of the prior art, the present application provides an electrochromic material and a preparation method thereof, which can effectively solve the problem of structural damage and performance degradation of the electrochromic material caused by chemical reaction or dissolution with the electrolyte.
[0005] To achieve the above-mentioned purposes, the present application is implemented by the following technical solutions: The present application provides a preparation method of an electrochromic material, comprising the following steps: a. providing a polymer matrix selected from one or more of polyvinyl alcohol, polymethyl methacrylate, and polyurethane; b. grafting a cathode electrochromic material onto the polymer matrix, wherein the cathode electrochromic material is selected from one or more of lithium ion-doped tungsten oxide, lithium-doped molybdenum oxide, and polypyrrole; in actual selection, the cathode electrochromic material can also be one of tungsten oxide, molybdenum oxide, titanium oxide, diosmium pentoxide, and niobium oxide; the thickness of the cathode electrochromic material is 100 nm-500 nm; c. Grafting an anodic electrochromic material onto the polymer matrix, wherein the anodic electrochromic material is selected from one or more of chromium-doped nickel oxide, lithium-doped nickel oxide, or polythiophene; in actual selection, the anodic electrochromic material can also be one of nickel oxide, chromium oxide, iridium oxide, indium nitride, crystalline tungsten oxide, oxygen-rich tungsten oxide, and Prussian blue, and the thickness of the anodic electrochromic material is 80 nm to 400 nm; d. Placing the grafted polymer matrix in an electrolyte containing an electrolyte, stirring or mixing helps to uniformly disperse the electrolyte and ensures that it is fully in contact with the polymer matrix, prompting the polymer matrix to form a gel-like structure; e. Forming an electrochromic material with a gel-like structure by solidification treatment in the electrolyte.
[0006] Preferably, the electrolyte is one or more of lithium bromide, lithium nitrate, or lithium sulfate.
[0007] Preferably, Temperature control: After placing the grafted polymer matrix in an electrolyte containing an electrolyte, the solidification treatment should be carried out at a temperature in the range of 20°C to 80°C, which helps to promote the formation and stability of the electrochromic material, while avoiding irreversible changes in the material structure or performance; pH adjustment: During the solidification process, the pH of the electrolyte needs to be adjusted to maintain it within the range of 3 to 7, good pH control helps to maintain the stability and performance of the electrochromic material, ensuring that the cathode and anode electrochromic materials grafted onto the polymer matrix can fully exert their functions; Solidification time and process: The solidification time depends on factors such as electrolyte composition, temperature, and pH, ensuring complete solidification of the material while avoiding excessive solidification time to prevent cost increases or material performance degradation; Through temperature control, pH adjustment, and control of solidification time and process, cross-linking or gelation reactions occur between the polymer matrix and the grafted electrochromic material, forming a gel-like electrochromic material.
[0008] Preferably, the ions and impurities remaining in the electrolyte are washed out to prevent affecting the performance of the final product; Using appropriate solvents or cleaning agents, the gel is washed to fully remove the electrolyte in the gel.
[0009] Preferably, the grafting of the cathode and anode electrochromic materials is achieved through physical adsorption or chemical covalent bonding.
[0010] Preferably, the electrochromic material is prepared according to the method of claim 1.
[0011] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects: Compared with the prior art, the present application can adjust the performance and application range of the electrochromic material by selecting different polymer matrices (such as polyvinyl alcohol, polymethyl methacrylate, polyurethane, etc.), so as to meet the needs of different applications. The use of lithium bromide, lithium nitrate or lithium sulfate as the electrolyte, and the good pH value adjustment and appropriate curing temperature and time control, can help to maintain the stability and performance of the electrochromic material, and ensure that no irreversible change occurs during long-term use. DETAILED DESCRIPTION
[0012] To make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments of the present application. Obviously, the described embodiments are some embodiments but not all embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.
[0013] The present application will be further described below in conjunction with the embodiments.
[0014] Embodiment: A method for preparing an electrochromic material, comprising the following steps: a. providing a polymer matrix, the polymer matrix being selected from one or more of polyvinyl alcohol, polymethyl methacrylate and polyurethane; b. grafting a cathode electrochromic material onto the polymer matrix, wherein the cathode electrochromic material is selected from one or more of lithium ion doped tungsten oxide, lithium doped molybdenum oxide and polypyrrole; the thickness of the cathode electrochromic material is 300 nm; c. grafting an anode electrochromic material onto the polymer matrix, wherein the anode electrochromic material is selected from chromium doped nickel oxide; the thickness of the anode electrochromic material is 200 nm; d. placing the grafted polymer matrix in an electrolyte containing an electrolyte, and stirring or mixing to help the electrolyte disperse uniformly and ensure that it is in full contact with the polymer matrix, so as to promote the polymer matrix to form a gel-like structure; e. forming an electrochromic material with a gel-like structure through curing treatment in the electrolyte.
[0015] The electrolyte is one or more of lithium bromide, lithium nitrate and lithium sulfate.
[0016] In some alternative embodiments, the anodic electrochromic material is selected from lithium-doped nickel oxide or polythiophene.
[0017] Temperature control: After the grafted polymer matrix is placed in an electrolyte containing electrolyte, the temperature of the curing process should be in the range of 20°C to 80°C, which helps to promote the formation and stability of electrochromic materials, while avoiding irreversible changes in material structure or performance; pH adjustment: During the curing process, the pH of the electrolyte needs to be adjusted to maintain a range of 3 to 7, good pH control helps to maintain the stability and performance of the electrochromic material, and ensures that the cathode and anode electrochromic materials grafted to the polymer matrix can fully function; Curing time and process: The curing time depends on factors such as electrolyte composition, temperature and pH, ensuring complete curing of the material while avoiding excessive curing time to prevent cost increases or material performance degradation; Through temperature control, pH adjustment, and control of curing time and process, cross-linking or gelation reactions occur between the polymer matrix and the grafted electrochromic material, forming a gel-like electrochromic material.
[0018] Wash the remaining ions and impurities in the electrolyte to prevent affecting the performance of the final product; Use appropriate solvents or cleaning agents to wash the gel to fully remove the electrolyte in the gel.
[0019] In which the grafting of cathode and anode electrochromic materials is formed by physical adsorption or chemical covalent bond.
[0020] The present application provides an electrochromic material made according to the above preparation method.
[0021] The working principle of the present application is as follows: Material preparation, when selecting polyamide or polycarbonate as the matrix of electrochromic material, their excellent mechanical strength and chemical stability need to be considered, for example: Polyvinyl alcohol: a synthetic polymer soluble in water, with good peptizing and film-forming properties, in electrochromic materials, polyvinyl alcohol can be used as a carrier or support matrix to fix and stabilize electrochromic agent molecules; Polymethyl methacrylate: a transparent organic glass material with good optical properties and chemical stability, in electrochromic materials, polymethyl methacrylate can be used as a substrate or protective layer to provide appropriate support and protection; Polyurethane: A synthetic material with excellent elasticity and wear resistance, widely used in coatings, adhesives, and elastomers; All three can stably accommodate electrochromic materials, enhancing their reliability and durability, and have good resistance to chemical substances under different environmental conditions; In the preparation of cathode and anode electrochromic materials, the cathode material is usually a substance that can change color or transmittance when reduced, while the anode material produces a color change effect when oxidized; The cathode electrochromic material is selected from: Lithium-ion-doped tungsten oxide: A classic electrochromic material that can undergo redox reactions under the action of an electric field when doped with lithium ions, changing its electronic structure and absorption properties; Lithium-doped molybdenum oxide: In electrochromic materials, it can act as a stabilizer or enhancer, helping to improve the optical stability and long-term durability of the material; Polyacetylene: A conductive polymer with excellent electrochromic properties. It can transform between different oxidation states, achieving electrochromic effects; The anode electrochromic material is selected from: Chromium-doped nickel oxide: An anode electrochromic material that changes the electronic structure of nickel oxide by doping with chromium ions, allowing it to undergo redox reactions under an electric field; Lithium-doped nickel oxide: In electrochromic materials, it is an anode material that participates in the redox process, enabling the color change of the material; Polythiophene: A conductive polymer with excellent electrochromic properties. It can undergo redox reactions under an electric field, changing its own electronic structure and absorption properties, and exhibiting obvious electrochromic effects.
[0022] Grafting process, pre-treatment of the surface of the polymer matrix to increase its binding ability with the electrochromic material, which can include surfactant treatment, chemical functionalization, or physical adsorption, etc. Grafting the above-mentioned cathode and anode electrochromic materials onto the surface or internal structure of the polymer matrix, through chemical reactions or physical adsorption, for example, using copolymerization (by copolymerizing the precursor molecules of the electrochromic material with the monomers in the polymer matrix, the electrochromic material is chemically anchored to the polymer chain, which ensures that the material is combined with the polymer at the molecular level, thereby improving adhesion and stability), rolling or spin coating to achieve this step, ensuring that the electrochromic material is uniformly and firmly attached to the polymer matrix.
[0023] Solidification into a gel, preparing a suitable electrolyte, ensuring that it contains enough solvent and electrolyte to support the cross-linking or rearrangement reactions of the electrochromic material; Solvents: such as ethylene glycol, glycerol, etc., capable of effectively dissolving the precursors or reaction products of the electrochromic material and providing the necessary solubility and reaction environment in the reaction; The selection of appropriate solvents can ensure the stability and uniformity of the electrochromic material during the curing process, and the solvents should be able to effectively dissolve the precursors or reaction products of the electrochromic material and maintain a stable reaction environment under electrochemical conditions; Electrolyte: lithium bromide as a form of lithium bromide, can act as an ion conductor in the electrochromic material, helping to transmit charges and flow of ions, which is crucial for the electrochromic phenomenon, because it involves the movement of ions and the occurrence of redox reactions under the action of an electric field; Lithium nitrate as an ion conductor, helps to control the progress of electrochemical reactions, it promotes the redox reactions inside the material under the action of an electric field, resulting in color changes or other desired electrochromic effects; Lithium sulfate also plays a role in ion transport in electrochromic materials, helping to control the progress of electrochemical reactions, it can affect the electrochemical properties of the material, and in turn affect its response to changes in electric field and color change effect.
[0024] The electrolyte can adjust the ionic strength and pH of the electrolyte, affecting the rate and effect of the reaction; The above solvents and electrolytes are formulated into different electrolytes, the grafted polymer matrix is placed in one of the above electrolytes, and appropriate electric field (the strength of the electric field should be determined according to the specific electrochromic material and the characteristics of the solution, usually need to be tested to determine the best voltage and current density, the voltage can be between several volts to several tens of volts, depending on the electrochemical properties of the material) or chemical conditions (if chemical conditions are used at the same time as the electric field, such as adjusting the pH of the solution or adding catalysts, the application time and duration of the conditions need to be determined according to the specific chemical reaction rate), these conditions help to form a gel-like structure inside the polymer matrix, and the gel is cured by rearrangement or cross-linking reaction of the electrochromic material, during which the different electrolytes allow the polymer matrix to form a gel-like structure, and the best electrochromic material is detected through subsequent tests during the process; Subsequent processing and separation, the cured gel material is washed several times to completely remove the residual substances in the electrolyte, preventing the influence on the performance of the final product; The washed gel material is subjected to appropriate drying treatment to ensure that the gel material reaches the desired dry state for further performance testing or application.
[0025] In the adjustment of pH value and the control of proper curing temperature and time, the stability and performance of the electrochromic material are maintained by matching different electrolytes through various polymer matrices, forming a gel-like structure in the polymer matrix.
[0026] The following further describes the steps of further preparing an electrochromic device from the electrochromic material prepared by the technical solution: S1, substrate pretreatment; FTO (fluorine-doped tin oxide) conductive glass is selected as the device substrate, and is sequentially ultrasonically cleaned with deionized water, ethanol and acetone for 18 minutes, and then is dried and irradiated with ultraviolet light for 10 minutes to remove the residual organic matter on the surface; S2, conductive layer activation; the device substrate pretreated in step S1 is placed in a plasma cleaning machine, and the surface activity of the conductive layer is improved by treating it in the plasma cleaning machine for 6 minutes to enhance the adhesion between the conductive layer and the electrochromic layer; S3, electrochromic layer coating; the gel-like electrochromic material prepared by the technical solution is coated on the conductive surface of two device substrates by spin coating, the cathode electrochromic layer corresponds to one device substrate, and the anode electrochromic layer corresponds to the other device substrate, and then is dried at room temperature for 30 minutes; S4, device assembly; the two device substrates coated with the electrochromic layer are aligned with the electrochromic layer opposite each other, a sealant is laid on the edge, the sealant is 80μm thick, a liquid injection port is reserved, and the device is fixed by a pressing machine.
[0027] S5, injection of electrolyte; the electrolyte containing electrolyte is injected into the device through the reserved liquid injection port to ensure that the electrolyte fills the gap between the two electrochromic layers, and then the liquid injection port is sealed with a sealant.
[0028] S6, curing; the assembled device is placed in a constant temperature oven at 40℃ for 2-4 hours to complete the preparation of the electrochromic device.
[0029] The above is only an embodiment of the present application, and well-known specific technical solutions and / or common knowledge of characteristics in the scheme are not described in detail. It should be noted that for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific embodiments described in the specification can be used to explain the content of the claims.
Claims
1. A method for preparing an electrochromic material, characterized in that, Includes the following steps: a. Provides a polymer matrix selected from one or more of polyvinyl alcohol, polymethyl methacrylate, and polyurethane; b. Grafting a cathode electrochromic material onto the polymer matrix, wherein the cathode electrochromic material is selected from one or more of lithium-ion-doped tungsten oxide, lithium-doped molybdenum oxide, or polypyrrole; the thickness of the cathode electrochromic material is 100 nm-500 nm. c. Grafting an anodic electrochromic material onto the polymer matrix, wherein the anodic electrochromic material is selected from one or more of chromium-doped nickel oxide, lithium-doped nickel oxide, or polythiophene; the thickness of the anodic electrochromic material is 80 nm-400 nm. d. Place the grafted polymer matrix in an electrolyte solution containing electrolytes. Stirring or mixing helps to evenly disperse the electrolytes and ensures that they are in full contact with the polymer matrix, promoting the formation of a gel-like structure in the polymer matrix; e. By solidification treatment in the electrolyte, an electrochromic material with a gel-like structure is formed.
2. The method for preparing the electrochromic material according to claim 1, characterized in that, The electrolyte is one or more of lithium bromide, lithium nitrate, or lithium sulfate.
3. The method for preparing the electrochromic material according to claim 1, characterized in that, Temperature control: After the grafted polymer matrix is placed in an electrolyte containing electrolyte, the curing temperature should be in the range of 20°C to 80°C. Temperatures within this range help promote the formation and stability of electrochromic materials while avoiding irreversible changes in the material's structure or properties. pH adjustment: During the curing process, the pH value of the electrolyte needs to be adjusted to maintain it within the range of 3 to 7. Good pH control helps maintain the stability and performance of the electrochromic material, ensuring that the cathode and anodic electrochromic materials grafted onto the polymer matrix can fully perform their functions. Curing time and process: The curing time depends on factors such as electrolyte composition, temperature, and pH value. While ensuring complete curing of the material, it is important to avoid excessively long curing times to prevent increased costs or deterioration of material performance. By controlling the temperature, pH value, curing time, and process, the polymer matrix and the grafted electrochromic material are cross-linked or gelled to form a gel-like electrochromic material.
4. The method for preparing the electrochromic material according to claim 1, characterized in that, Residual ions and impurities in the electrolyte are washed away to prevent them from affecting the performance of the final product. Use a suitable solvent or cleaning agent to wash the gel to thoroughly remove the electrolytes from it.
5. The method for preparing the electrochromic material according to claim 1, characterized in that, in, The grafting of the cathode and anode electrochromic materials is formed through physical adsorption or chemical covalent bonding.
6. An electrochromic material, characterized in that, It is prepared according to the method for preparing electrochromic materials according to claim 1.