CN114859613B - Liquid electrolyte and preparation method thereof, electrochromic device and preparation method thereof - Google Patents

Abstract

The present invention provides a liquid electrolyte and a preparation method thereof, an electrochromic device and a preparation method thereof, wherein the electrochromic device comprises, from top to bottom, a first substrate, a first electrode layer, a packaging gasket, a second electrode layer, and a second substrate; the packaging gasket is a hollow annular structure; the first electrode layer, the packaging gasket, and the second electrode layer form a closed electrolyte cavity; the electrolyte cavity is filled with a liquid electrolyte; after a voltage is applied to the first electrode layer and the second electrode layer, the electrochromic device changes from a transparent light-transmitting state to a dark light-blocking state, and then from a dark light-blocking state to a mirror-reflecting state. The present invention modifies the solvent by changing its material or introducing an additive, so that the present invention can still work normally under low temperature conditions.

Description

Liquid electrolyte and preparation method thereof, electrochromic device and preparation method thereof

Technical Field

The present invention relates to the field of optoelectronic technology, and in particular to a liquid electrolyte and a preparation method thereof, an electrochromic device and a preparation method thereof.

Background technique

As energy demand continues to increase, people are increasingly interested in reducing energy consumption. Therefore, materials or devices that can convert or save energy have received widespread attention. Electrochromic/reflective technology can effectively control the propagation of visible light and infrared heat, and has the characteristics of single reversibility and multiple cycles. In the past few decades, various applications of electrochromic/reflective devices have been developed, such as smart windows with sunlight attenuation, anti-glare rearview mirrors, wearable energy devices, and reflective or transmissive electronic displays. At present, electrochromic/reflective devices generally use metal reversible electrodeposition, and the solvent material is mainly dimethyl sulfoxide (DMSO). Among them, the solvent, as the main component of the liquid electrolyte, has a decisive influence on the physical properties of the device, such as melting and boiling points.

The electroreflective/chromic device based on silver reversible electrodeposition is affected by the solvent DMSO, and the lowest working temperature of the electrochromic device with metal deposition can only reach about 18°C above zero, which seriously limits the working conditions of the device. The purpose of the present invention is to reduce the lowest working temperature of the device so that the device can still work normally at minus 50°C.

Summary of the invention

In view of the above problems, the purpose of the present invention is to provide a liquid electrolyte and a preparation method thereof, an electrochromic device and a preparation method thereof. By changing the material of the solvent or introducing additives to modify it, the device can still work normally at low temperatures and can complete the conversion between a transparent light-transmitting state, a dark light-blocking state, and a mirror-reflecting state.

To achieve the above object, the present invention adopts the following specific technical solutions:

The invention provides a liquid electrolyte, comprising an antifreeze solvent and a solute.

Preferably, N-methylpyrrolidone, propylene carbonate, tetrahydrofuran or acetonitrile is used as the antifreeze solvent of the liquid electrolyte;

Or the antifreeze additive is dissolved in DMSO as the antifreeze solvent of the liquid electrolyte.

Preferably, the antifreeze additive is: methanol, ethanol, ethylene glycol, n-propanol or isopropanol; the proportion of the antifreeze additive is 40%-70%.

Preferably, the solutes of the liquid electrolyte are: soluble metal salt, supporting electrolyte and gel polymer.

The present invention also provides a method for preparing a liquid electrolyte, comprising adding a soluble metal salt, a supporting electrolyte and a gel polymer to an antifreeze solvent, and stirring the mixture at a temperature of 40-65° C. for 4-10 hours;

The content of soluble metal salts is 40-80mmol/L.

The ratio of the content of the supporting electrolyte to the soluble metal salt is 2-20:1;

The content of the gel polymer is 0-12 wt%.

The present invention also provides an electrochromic device, which comprises, from top to bottom, a first substrate, a first electrode layer, a packaging gasket, a second electrode layer, and a second substrate;

The packaging gasket is a hollow annular structure;

The first electrode layer, the packaging gasket and the second electrode layer form a closed electrolyte cavity; the electrolyte cavity is filled with a liquid electrolyte;

After voltage is applied to the first electrode layer and the second electrode layer, the electrochromic device changes from a transparent light-transmitting state to a dark light-blocking state, and then from the dark light-blocking state to a mirror-like light-reflecting state.

The present invention also provides a method for preparing an electrochromic device, comprising the following steps:

S1, preparing a first electrode layer and a second electrode layer on a first substrate and a second substrate respectively;

S2, making the packaging gasket into a ring structure and placing it on the second electrode layer;

S3, placing the first substrate on the packaging gasket to form an electrolyte cavity, and injecting the liquid electrolyte into the electrolyte cavity through the injection hole;

S4. The electrochromic device is sealed by hot melt adhesive.

Preferably, the method further comprises a pre-treatment step S0: cleaning the first substrate and the second substrate.

Preferably, the materials of the first electrode layer and the second electrode layer are: ITO, FTO, inert metal grid or CVD graphene.

Preferably, the packaging gasket is made of polytetrafluoroethylene material, and the thickness of the packaging gasket is 60 μm-1000 μm.

Compared with the existing technology, the present invention modifies the solvent by changing the material of the solvent or introducing additives, so that the device can still work normally at low temperatures and can complete the conversion between a transparent light-transmitting state, a dark light-blocking state, and a mirror-like light-reflecting state.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic structural diagram of an electrochromic device according to a third embodiment of the present invention.

FIG. 2 is a flow chart of a method for preparing an electrochromic device according to a fourth embodiment of the present invention.

The reference numerals include: a first substrate 1 , a packaging gasket 2 , a first electrode layer 3 , an electrolyte cavity 4 , a second electrode layer 5 and a second substrate 6 .

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, the same modules are represented by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, the detailed description thereof will not be repeated.

In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

The first embodiment of the present invention provides a liquid electrolyte, the liquid electrolyte comprising: an antifreeze solvent and a solute. The liquid electrolyte provided by the present invention has an antifreeze effect at low temperatures.

The antifreeze solvent may be: N-Methyl pyrrolidone (NMP), propylene carbonate, tetrahydrofuran, acetonitrile, an antifreeze additive dissolved in DMSO as a mixed solvent, or other materials with a low melting point and capable of dissolving the solute.

The antifreeze additive can be methanol, ethanol, ethylene glycol (EG), n-propanol, isopropanol (IPA) or other antifreeze materials that are miscible with DMSO. The proportion of the antifreeze additive is 40%-70%.

Solutes include: soluble metal salts, supporting electrolytes and gel polymers.

The soluble metal salt may be: AgNO ₃ , CuCl ₂ , etc.;

The supporting electrolyte may be: tetrabutylammonium bromide (TBABr), tetrabutylammonium chloride, tetrabutylammonium iodide, etc.;

The gel polymer may be: polyvinyl butyral (PVB), polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), hydroxyethyl cellulose (HEC), etc.

The second embodiment of the present invention provides a method for preparing a liquid electrolyte, which is as follows:

After adding the soluble metal salt, supporting electrolyte and gel polymer to the antifreeze solvent, stirring at a temperature of 40-65°C for 4-10 hours;

The content of soluble metal salts is 40-80mmol/L;

The ratio of the content of supporting electrolyte to soluble metal salt is 2-20:1;

The content of the gel polymer is 0-12 wt%.

FIG. 1 shows an electrochromic device according to a third embodiment of the present invention.

As shown in FIG. 1 , the electrochromic device provided by the third embodiment of the present invention includes: a first substrate 1 , a packaging gasket 2 , a first electrode layer 3 , an electrolyte cavity 4 , a second electrode layer 5 and a second substrate 6 .

The second electrode layer 5 is located above the second substrate 6 . The packaging gasket 2 is located on the second substrate 6 . The first electrode layer 3 is arranged above the packaging gasket 2 . The first substrate 1 is located above the first electrode layer 3 .

The packaging gasket 2 is a hollow annular structure, the lower surface of the packaging gasket 2 contacts the second electrode layer 5, and the upper surface of the packaging gasket 2 contacts the first electrode layer 3. The packaging gasket 2 is staggered from the first electrode layer 3 and the second electrode layer 5.

The enclosed space formed by the packaging gasket 2 , the first electrode layer 3 and the second electrode layer 5 is an electrolyte chamber 4 .

The electrolyte chamber 4 is filled with liquid electrolyte.

Under the driving voltage of 2.5V, the device whose solvent is NMP or a mixture of methanol and DMSO gradually changes from a transparent light-transmitting state to a dark light-blocking state, and then gradually changes from a dark light-blocking state to a mirror-like light-reflecting state. After the voltage is removed, the metal mirror gradually dissolves, and changes from a mirror-like light-reflecting state to a dark light-blocking state, until it becomes a transparent light-transmitting state. Since the device is a symmetrical structure, the electrochromic device provided by the present invention will also work normally under the driving voltage of reverse voltage.

The working principle of the gas-induced chromic device provided by the present invention is: under the action of DC voltages in different directions, the metal ions in the liquid electrolyte are reduced to metal elements and deposited in the first electrode layer 3 or the second electrode layer 5 .

When deposited on the first electrode layer 3 , a metal mirror film with high reflectivity will be formed due to the smooth surface of the first electrode layer 3 . Similarly, when deposited on the second electrode layer 5 , a metal mirror film with high reflectivity will also be formed.

At the same time, due to the influence of surface plasmons, the device using NMP as a solvent will appear dark during the deposition process. Finally, if the voltage applied to both sides of the first electrode layer and the second electrode layer is removed, the metal element will gradually dissolve into the liquid electrolyte, so that the device returns to a transparent and light-transmitting state. The entire color change process is completely reversible. Because the liquid electrolyte is added to the electrochromic device provided by the present invention, it can still work normally in a low temperature environment.

FIG. 2 shows a flow chart of a method for preparing an electrochromic device according to a fourth embodiment of the present invention.

As shown in FIG. 2 , the method for preparing an electrochromic device provided in the fourth embodiment of the present invention comprises the following steps:

S0, pretreatment step: cleaning the first substrate and the second substrate.

Prepare a glass substrate, i.e., a substrate. First, wipe the substrate with acetone or ethanol, then provide ultrasonic cleaning and drying.

S1. Prepare a first electrode layer and a second electrode layer on a first substrate and a second substrate respectively.

A first electrode layer is sputtered on the first substrate, and a second electrode layer is sputtered on the second substrate; materials of the electrode layers are: ITO and FTO, inert metal grid, CVD graphene, etc.

S2. Make the packaging gasket into a ring structure and place the packaging gasket on the second electrode layer.

The packaging gasket is made of 60-1000μm thick polytetrafluoroethylene material.

S3. Cover the packaging gasket with the side of the first substrate carrying the first electrode layer facing downward to form a closed electrolyte cavity, and inject the liquid electrolyte into the electrolyte cavity through the injection hole.

S4. The electrochromic device is sealed by hot melt adhesive.

The liquid electrolyte is injected into the electrolyte cavity through the injection hole, and then the injection hole is sealed with hot melt adhesive.

Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims (5)

1. An electrochromic device made of liquid electrolyte, characterized in that it comprises, from top to bottom, a first substrate, a first electrode layer, a packaging gasket, a second electrode layer and a second substrate; The packaging gasket is a hollow annular structure; The first electrode layer, the packaging gasket and the second electrode layer form a closed and symmetrical electrolyte cavity; the electrolyte cavity is filled with a liquid electrolyte; Liquid electrolytes include: antifreeze solvents and solutes; Using N-methylpyrrolidone as an antifreeze solvent for the liquid electrolyte; Or dissolving an antifreeze additive in DMSO as the antifreeze solvent of the liquid electrolyte, the antifreeze additive is: methanol, ethanol, ethylene glycol, n-propanol or isopropanol, and the proportion of the antifreeze additive is 40%-70%; The solutes of the liquid electrolyte are: soluble metal salt, supporting electrolyte and gel polymer; After adding the soluble metal salt, the supporting electrolyte and the gel polymer to the antifreeze solvent, stirring at a temperature of 40-65° C. for 4-10 hours; The content of the soluble metal salt is 40-80 mmol/L; The ratio of the supporting electrolyte to the soluble metal salt is 2-20:1; The content of the gel polymer is 0-12wt%; The soluble metal salt is AgNO ₃ or CuCl ₂ ; The supporting electrolyte is tetrabutylammonium bromide, tetrabutylammonium chloride or tetrabutylammonium iodide; The gel polymer is polyvinyl butyral, polyvinyl alcohol, polyvinyl pyrrolidone, polyethylene glycol or hydroxyethyl cellulose; After applying a forward or reverse 2.5V voltage to the first electrode layer and the second electrode layer, the electrochromic device changes from a transparent light-transmitting state to a dark light-blocking state, and then from the dark light-blocking state to a mirror light-reflecting state; after removing the voltage, the metal mirror gradually dissolves, and changes from the mirror light-reflecting state to a dark light-blocking state until it becomes a transparent light-transmitting state. 2. A method for preparing an electrochromic device according to claim 1, characterized in that it comprises the following steps: S1. preparing the first electrode layer and the second electrode layer on the first substrate and the second substrate respectively; S2, making the packaging gasket into a ring structure and placing it on the second electrode layer; S3, placing the first substrate on the packaging gasket to form the electrolyte cavity, and injecting the liquid electrolyte into the electrolyte cavity through the injection hole; S4. Hermetically packaging the electrochromic device using hot melt adhesive. 3 . The method for preparing an electrochromic device according to claim 2 , further comprising a pretreatment step S0 : cleaning the first substrate and the second substrate. 4 . The method for preparing an electrochromic device according to claim 3 , wherein the material of the first electrode layer and the second electrode layer is: ITO, FTO, an inert metal grid or CVD graphene. 5 . The method for preparing an electrochromic device according to claim 4 , wherein the packaging gasket is made of polytetrafluoroethylene material, and the thickness of the packaging gasket is 60 μm-1000 μm.