CN220873421U - Flexible electrochromic capacitor - Google Patents

Abstract

The utility model provides a flexible electrochromic capacitor which comprises a conductive layer, a color-changing layer, an electrolyte layer and a galvanized electrode layer which are sequentially stacked, wherein the galvanized electrode layer is in a grid structure. In the flexible electrochromic capacitor, the galvanized electrode layer serving as the anode is gridded, so that the thickness of the electrochromic capacitor is reduced, important parameters such as square resistance, transparency and mechanical property can be regulated and controlled by changing the period, line width and grid shape of the grid-shaped structure, and the zinc loading capacity of the galvanized electrode layer can be controlled, thereby overcoming the serious dendrite problem generated by adopting zinc foil as an electrode in the conventional electrochromic device and prolonging the service life of the device.

Description

A flexible electrochromic capacitor

Technical Field

The utility model relates to the technical field of electrochromic devices, in particular to a flexible electrochromic capacitor.

Background technique

Electrochromism is a phenomenon in which the optical properties of a material (reflectivity, transmittance, absorptivity, etc.) undergo stable and reversible color changes under the action of an external electric field, which is manifested in the form of reversible changes in color and transparency. Materials with electrochromic properties are called electrochromic materials, and devices made of electrochromic materials are called electrochromic devices.

Electrochromic devices refer to devices whose colors can be reversibly changed by coloring and fading under the action of alternating positive and negative voltages. Its main application areas include smart windows, display technology, military camouflage, flexible wearable devices, and anti-glare rearview mirrors. The emergence of electronic skin products in the fields of smart wearables and medical testing requires the development of ultra-thin, attachable, and high-performance smart flexible batteries. In this context, electrochromic capacitor (battery) dual-function devices have attracted much attention. This device has become a popular choice for smart power supply equipment because it has the energy storage function of a supercapacitor (battery) and the electrochromic function of regulating optical properties according to voltage, especially in electrochromic supercapacitors (batteries) using zinc anodes. Because zinc has strong reducibility, can quickly self-discharge, and exhibits high stability and high capacity in aqueous electrolytes, it has attracted much attention. However, current zinc anode electrochromic supercapacitors (batteries) usually use metal foils (zinc foil) of various shapes as electrodes, which leads to three major problems: first, zinc foil releases a large amount of zinc ions, resulting in serious fixed dendrite problems, which shortens the life of the device; second, the electric field generated by zinc foil is often uneven, which affects the color change effect; finally, zinc foil is relatively thick, which will increase the thickness and weight of the device and is not very suitable for flexible and wearable applications.

Utility Model Content

The utility model aims to provide a flexible electrochromic capacitor and a preparation method thereof, so as to solve the problems of short device life, poor color change effect, increased device thickness and weight and unsuitability for flexible and wearable applications.

The technical solution for achieving the purpose of the utility model is as follows: the utility model provides a flexible electrochromic capacitor, comprising a conductive layer, a color-changing layer, an electrolyte layer and a galvanized electrode layer stacked in sequence, and the galvanized electrode layer has a grid structure.

In one embodiment of the utility model, the conductive layer is a metal grid electrode; the galvanized electrode layer is zinc deposited on the surface of the grid electrode, and the material of the metal grid electrode is silver, copper, or nickel.

In an embodiment of the present invention, the depth-to-width ratio of the metal grid electrode is less than 2:1; and the grid period of the metal grid electrode is 50 μm-200 μm.

In one embodiment of the utility model, the electrolyte layer is an electrolyte layer containing zinc ions, including a hydrogel containing zinc ions; the electrolyte layer is flexible and stretchable; the transmittance of the electrolyte layer is greater than 80%; the thickness of the electrolyte layer is 100μm-200μm.

In an embodiment of the present invention, the color-changing layer has a single-layer structure including PEDOT:PSS.

In one embodiment of the present invention, the color-changing layer is a double-layer or multi-layer structure, including a side close to the conductive layer made of PEDOT:PSS; and a side away from the conductive layer made of tungsten trioxide or Prussian blue.

The utility model has the following beneficial effects compared with the prior art: in the flexible electrochromic capacitor of the utility model, the galvanized electrode layer serving as the anode is gridded, thereby reducing the thickness of the electrochromic capacitor, and by changing the period, line width and grid shape of the grid structure, it is possible to regulate important parameters such as square resistance, transparency and mechanical properties, and it is also possible to control the zinc loading amount of the galvanized electrode layer, thereby overcoming the serious dendrite problem caused by the existing electrochromic devices using zinc foil as electrodes and improving the service life of the devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic structural diagram of a flexible electrochromic device according to an embodiment of the present invention.

Detailed ways

The following is a further detailed description of the specific implementation of the present invention in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

The utility model provides a flexible electrochromic device. As shown in FIG1 , a flexible electrochromic capacitor of an embodiment includes a conductive layer 11, a color-changing layer 12, an electrolyte layer 13 and a galvanized electrode layer 14 which are stacked in sequence, and the galvanized electrode layer 14 has a grid structure.

In the flexible electrochromic capacitor of the utility model, a galvanized electrode layer 14 is provided on the conductive layer 11, and the galvanized electrode layer 14 has a grid structure, which reduces the thickness of the electrochromic capacitor. By changing the period, line width and grid shape of the grid structure, important parameters such as square resistance, transparency and mechanical properties can be regulated. The zinc loading amount of the galvanized electrode layer 14 can also be controlled, thereby overcoming the serious dendrite problem caused by the existing electrochromic device using zinc foil as an electrode and improving the service life of the device.

In this embodiment, the galvanized electrode layer 14 is zinc deposited on the surface of the metal mesh electrode, and the metal mesh electrode is used to provide support for the galvanized electrode layer 14. The material of the metal mesh electrode is usually a highly conductive metal such as silver, copper, and nickel, and the specific material selected in this embodiment is nickel.

It should be noted that the metal mesh electrode deposited with zinc in the galvanized electrode layer 14 and the conductive layer 11 are the same metal mesh electrode, that is, the conductive layer 11 is a nickel metal mesh electrode layer, and the galvanized electrode layer 11 is a nickel metal mesh plated with zinc.

In this embodiment, the depth-to-width ratio of the metal mesh electrode is less than 2: 1. Those skilled in the art can set the depth-to-width ratio of the metal mesh electrode according to actual conditions, and no sole limitation is made here.

In this embodiment, the galvanized electrode layer 14 includes a plurality of first grid units, and the first grid units are any one of a circle, an ellipse, a regular octagon, a regular hexagon or a gourd shape, or a combination of multiple of the above.

In this embodiment, the conductive layer 11 also has a grid structure, that is, the conductive layer 11 is a metal grid electrode. The conductive layer 11 includes a plurality of second grid units, which are any one of a circle, an ellipse, a regular octagon, a regular hexagon or a gourd shape or a combination of multiple shapes.

The use of a grid-shaped conductive layer 11 and a galvanized electrode layer 14 can ensure that the electric field distribution of the electrochromic capacitor is more uniform. This is because the grid structure can distribute the electric field more evenly over the entire surface of the flexible electrochromic capacitor, reducing the difference in electric field gradients, thereby enhancing the stability and reliability of the device. By adjusting the grid line width and thickness, the optical properties of the electrochromic capacitor can be optimized. Selecting the line width and thickness in the above interval can reduce reflection and scattering, improve transmittance, and thus enhance the visual effect and usability of the device. At the same time, by adjusting the line width and thickness in the above interval, the desired electric field distribution can be achieved, thereby optimizing the electrochromic effect and energy consumption.

In this embodiment, the electrolyte layer 13 may be an electrolyte layer containing zinc ions, including a hydrogel containing zinc ions; the electrolyte layer 13 is flexible and stretchable, and its light transmittance is greater than 80%. The thickness of the electrolyte layer 13 is 100 μm to 200 μm. Those skilled in the art can set the thickness of the electrolyte layer to 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, etc. according to actual conditions, and this is not the only limitation.

In another preferred embodiment, the grid structure of the galvanized electrode layer 14 is a periodically distributed structure, and its period range is 50μm to 200μm. Correspondingly, the grid structure of the conductive layer 11 is a periodically distributed structure, and its period range is 50μm to 200μm. Those skilled in the art can set the period of the galvanized electrode layer 14 to 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 170μm, 180μm, 190μm, 192μm, 194μm, 198μm, 200μm, etc. according to actual needs, and this is not the only limitation. ; Those skilled in the art can set the period of the conductive layer 11 to 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 110μm, 120μm, 130μm, 140μm, 150μm, 160μm, 166μm, 170μm, 180μm, 184μm, 190μm, 198μm, 200μm, etc. according to actual needs, and no sole limitation is made here.

In this embodiment, the material of the conductive layer 11 is iron, copper, nickel, zinc, silver, gold, etc. In this embodiment, nickel metal is selected.

In the present embodiment, the color-changing layer 12 includes an electrochromic material, selected from any one or more of an organic electrochromic material, an inorganic electrochromic material or a composite electrochromic material. The mechanical electrochromic material includes a metal oxide, preferably tungsten trioxide or nickel oxide. The organic electrochromic material is preferably any one or more of violaceous, isophthalic acid esters, metal phthalocyanines, pyridine metal complexes, polyanilines, polypyrroles, and polythiophenes. The electrochromic material selected in the present embodiment is a mixed solution of polyethylene dioxythiophene (PEDOT) and polyphenylene acetate sulfonate (PSS). PEDOT:PSS has good electrical conductivity and capacitance properties, and is also a color-changing material, which is an ideal choice for the color-changing layer of an electrochromic device.

The electrolyte layer 13 may be an inorganic gel layer or an organic gel layer. The inorganic gel layer includes electrolytes such as acrylamide, sodium chloride, lithium chloride, sodium perchlorate, lithium perchlorate, and tetramethylethylenediamine, ammonium persulfate, and methylenebisacrylamide. The organic gel layer includes organic polymers such as acrylonitrile-styrene, curing agents such as 1-methylimidazole and 4-methylimidazole, electrolytes such as sodium chloride, lithium chloride, sodium perchlorate, lithium perchlorate, and organic solvents such as acetonitrile, tetrahydrofuran, and toluene.

In the present embodiment, the electrolyte layer 13 is an organic gel layer, in which the main material is a hydrogel. A hydrogel is a gel system composed of water molecules and a polymer, wherein the polymer is usually an organic compound, such as polyacrylamide or polyacrylic acid. The hydrogel has a high water absorption and can absorb a large amount of water, thereby providing a good ion transmission channel. This helps the transmission and movement of ions in the electrolyte and promotes the electrochromic effect of the device. At the same time, the hydrogel can undergo a gel-sol transition under the action of water. When an electric field is applied, the water in the electrolyte layer can be absorbed to form a gel state, thereby changing the color of the device. When the electric field disappears, the water can be released, causing the gel to be transformed into a sol state, restoring the original color of the device.

The utility model also provides a method for manufacturing a flexible electrochromic capacitor, which is used to prepare any of the above-mentioned flexible electrochromic capacitors, comprising:

S1, forming a conductive layer 11 with a grid structure on a substrate, and then peeling the conductive layer 11 from the substrate;

S2, providing two substrates, and injecting an electrolyte solution between the two substrates to form an electrolyte layer 13;

S3, forming a color-changing layer 12 on a substrate, attaching an electrolyte layer 13 to the color-changing layer 12, and peeling the color-changing layer 12 from the substrate to obtain a composite layer including the color-changing layer 12 and the electrolyte layer 13;

S4, preparing a zinc ion complex solution for electrodeposition to form a zinc-plated electrode layer 14;

S5, encapsulating the conductive layer 11, the composite layer (the color-changing layer 12 and the electrolyte layer 13) and the zinc-plated electrode layer 14 to prepare a flexible electrochromic capacitor.

In another preferred embodiment, step S2 may further include immersing the electrolyte layer in a zinc-containing solution to supplement zinc ions, and obtaining a zinc-containing electrolyte layer after the zinc ions penetrate.

In step S3, the color-changing layer 12 is formed on the substrate, including spin coating the color-changing material on the substrate, and then drying at high temperature to obtain the color-changing layer 12.

In another preferred embodiment, in step S3, forming the color-changing layer 12 on the substrate includes spin coating a color-changing material on the substrate, then drying it at high temperature, then spin coating another color-changing material or electrochemically depositing another chemical, and then drying it at high temperature.

It should be noted that the substrate used in step 1 is a conductive substrate, such as ITO glass; the substrate used in step 2 is a glass substrate; the two substrates in step 3 are exactly the same, and the substrates are glass substrates.

The specific preparation process of the conductive layer 11 is as follows:

1. Apply photoresist on a conductive substrate (such as ITO glass), usually by spin coating or scraping, and control the thickness of the photoresist by combining the dilution degree of the photoresist. Usually the thickness is between 0.5μm and 10μm.

Specifically, those skilled in the art can set the thickness of the photoresist to 0.5μm, 1.0μm, 1.5μm, 2.0μm, 2.5μm, 3.0μm, 3.5μm, 4.5μm, 5.0μm, 6.0μm, 7.0μm, 8.0μm, 8.5μm, 9.0μm, or 10.0μm according to actual conditions.

2. Then use laser direct writing technology to form a grid-shaped structure of photoresist. You can also use etching to perform grid etching, and use a mask to expose and develop the photoresist to obtain the corresponding grid structure.

3. Place the developed ITO glass in the electroforming cell for electroforming, and deposit metal materials (such as silver, copper, nickel, etc.) in the exposed micro-grooves. The thickness of the metal material deposition can be observed by confocal microscopy. Metal grids of different thicknesses can be obtained according to different deposition times, but the height of the deposited metal cannot exceed the groove height, otherwise it will directly affect the transmittance of the metal grid.

After the conductive layer 11 is formed on the conductive substrate, it does not need support from the substrate material and can be bent freely. At the same time, the structure of the flexible electrochromic capacitor is simplified and the thickness is much lower than that of the existing electrochromic device, which improves the conductivity and overall transmittance of the flexible electrochromic capacitor and reduces the manufacturing cost.

In the color-changing layer 12, because the device requires capacitance and electrochromic properties, PEDOT:PSS is used for better conductivity and capacitance properties. It is also a color-changing material and is an ideal choice for the color-changing layer of the electrochromic device. PEDOT:PSS can also be regarded as part of the conductive electrode and other color-changing materials (such as tungsten trioxide, Prussian blue) can be superimposed under the PEDOT:PSS film to obtain a better color-changing effect. The preparation process is as follows:

1. Place the glass substrate in a plasma cleaning machine and clean it for 5-10 minutes to increase the hydrophilicity of the surface of the glass substrate.

2. Spin-coat the filtered PEDOT:PSS solution on a glass substrate (3000 rpm, 30 s), and then dry at 100°C for 5-10 minutes to obtain a PEDOT:PSS film. This step can be repeated 3 times to obtain a PEDOT:PSS film with a thickness of about 250 nm.

3. The hydrogel was attached to the glass substrate with the PEDOT:PSS film side, and heated at 100°C for 5 minutes, and then the hydrogel and the PEDOT:PSS film were peeled off. The hydrogel and PEDOT:PSS film were formed into an integrated structure, which greatly reduced the thickness of the device.

In order to manufacture wearable devices, the electrolyte layer 13 must first meet the requirements of ultra-thinness, flexibility and stretchability. Hydrogel not only meets the above requirements, but also has high light transmittance and strong ion transmission performance, making it the first choice for the electrolyte layer 13. The preparation steps are as follows:

1. First take 10 ml of deionized water, add 4 g of acrylamide monomer, 0.02 g of ammonium persulfate, and 0.004 g of N, N'-methylenebisacrylamide into the solution and stir at room temperature for 2 hours.

2. Drop the hydrogel solution between two glass substrates, use the capillary phenomenon to obtain a hydrogel film of controllable thickness (100 μm-200 μm), and then heat it at 100 °C for 5 min to obtain a solid hydrogel.

3. Immerse the hydrogel in a 2 mol/L zinc sulfate solution to supplement zinc ions, and obtain zinc ion hydrogel after zinc ion penetration. The hydrogel containing zinc ions can form a battery structure with a zinc anode.

After the deposition of metallic zinc, the zinc anode acts as a counter electrode, thereby promoting self-coloration through the redox potential gradient difference between the zinc anode and the electrochromic cathode. This self-coloration process does not require an external power source and has a self-powered function.

Since too low an operating current will induce a low level of metal nucleation sites on the substrate, thus limiting the subsequent crystal growth. If the operating current is too high, excessive metal nucleation sites will be deposited on the substrate, resulting in a larger bulk metal morphology. Accurate initial operating current can control different levels of nucleation growth, and the second stage current can change the driving force of the subsequent crystal growth level. Therefore, by regulating the stage current and the concentration of the deposition solution, the appropriate metal zinc loading can be found. The preparation process is as follows:

1. Prepare a zinc ion complex solution (such as zinc acetate, zinc sulfate solution). A higher concentration will cause the metal zinc on the surface of the nickel grid to form lumps. The concentration is usually 2 mol/L.

2. The three-electrode method is used for electrodeposition. A metal nickel grid is clamped to an electrode clamp as the working electrode, a platinum sheet or platinum wire electrode is used as the counter electrode, and a saturated calomel electrode is used as the reference electrode.

3. Deposition of metallic zinc is performed through the step current mode of the electrochemical workstation. Since the nanomorphology of the surface zinc is regulated by the step-like deposition voltage of metallic zinc, metal electrodes with different zinc loadings can be obtained. At the same time, the surface zinc layer has a good layered nanostructure, the electrochemical active area is greatly increased, and it has good charge and discharge performance.

The flexible electrochromic capacitor of this embodiment has a four-layer ultra-thin structure consisting of a nickel grid electrode (conductive layer 11), a PEDOT:PSS film (color-changing layer 12), a hydrogel (electrolyte layer 13) and a grid zinc electrode (galvanized electrode layer 14). The overall thickness of the flexible electrochromic capacitor does not exceed 250μm, which meets the requirements of ultra-thin and attachable wearable devices. The specific principle is that the working voltage drives the zinc ions to insert from the zinc anode into the working electrode, so that the color-changing layer 12 switches the corresponding color, and the zinc ions are inserted from the working electrode into the zinc anode during the discharge process. The zinc ions are interspersed in the color-changing layer 12 to achieve the color-changing and energy storage functions. At the same time, because zinc has a strong reducibility and forms a large potential difference with the working electrode, it can quickly self-discharge (self-colorize) without an external circuit, so that the flexible high electrochromic capacitor has excellent fast response time and high reversibility.

In this document, unless otherwise clearly specified or limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

In this document, the directions or positional relationships indicated by terms such as "up", "down", "front", "back", "left", "right", "top", "bottom", "inside", "outside", "vertical", and "horizontal" are based on the directions or positional relationships shown in the accompanying drawings and are only for the purpose of expressing the technical solution clearly and for the convenience of description. Therefore, they should not be understood as limitations on the present invention.

In this document, the terms "comprises," "comprising," or any other variations thereof, are intended to cover a non-exclusive inclusion of elements other than those listed and may also include additional elements not expressly listed.

The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed by the utility model, which should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims (6)

1. The flexible electrochromic capacitor is characterized by comprising a conductive layer, a color-changing layer, an electrolyte layer and a galvanized electrode layer which are sequentially stacked, wherein the galvanized electrode layer is in a grid-shaped structure.

2. The flexible electrochromic capacitor according to claim 1, wherein the conductive layer is a metal mesh electrode; the zinc plating electrode layer is formed by depositing zinc on the surface of the grid electrode, and the metal grid electrode is made of silver, copper and nickel.

3. The flexible electrochromic capacitor according to claim 2, wherein the metal grid electrode has a grid aspect ratio of less than 2:1; the mesh period of the metal mesh electrode is 50-200 mu m.

4. The flexible electrochromic capacitor according to claim 1, wherein the electrolyte layer is a zinc ion-containing electrolyte layer comprising a zinc ion-containing hydrogel; the electrolyte layer is flexible and stretchable; the electrolyte layer has a light transmittance of greater than 80%; the electrolyte layer has a thickness of 100 μm to 200 μm.

5. The flexible electrochromic capacitor according to claim 1, characterized in that said color-changing layer single-layer structure comprises PEDOT: PSS.

6. The flexible electrochromic capacitor according to claim 1, characterized in that the color-changing layer is a double-layer or multi-layer structure comprising PEDOT on the side close to the conductive layer: PSS; the material of one side far away from the conductive layer is tungsten trioxide or Prussian blue.