JPH06202164A - Electrochromic element and electrolyte film - Google Patents

Abstract

PURPOSE:To increase light transmittance and injected charge amt. of an electrochromic element during erasing. CONSTITUTION:The electrochromic element is produced by forming an electrochromic electrode 2 (e.g. WO3) via a transparent electrode 3 (collector electrode) on one transparent substrate 4, forming a counter electrode 5 on the other transparent substrate 6, and filling the space between these substrates 4, 6 with an electrolyte soln. 1. Hydrogen peroxide is added by 0.1-6wt.% (calculated as 31% hydrogen peroxide solution) to this electrolyte soln. 1 (electrolyte and solvent). Or, a solid electrolyte membrane prepared by filling pores of a polymer porous membrane with this electrolyte soln. may be used. As for the solvent, benzylnitrile, benzylcyanide, propylene carbonate, or gamma-butyrolactone is used. The solute is alkali metal salt, alkaline earth metal salt, etc.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electrochromic device and a solid electrolyte membrane.

[0002]

2. Description of the Related Art An element (ECD) that applies an electrochromic (EC) phenomenon in which the color of a substance reversibly changes according to a voltage is bright and easy to see, can display a large area, and has memory properties (low power consumption). ), Etc., and applications that take advantage of these characteristics, such as stock price displays, message boards, large display boards such as guide boards, anti-glare mirrors for automobiles, light control glass, light control elements such as sunglasses, etc. There is.

The structure of ECD is made by disposing an electrolyte between an electrochromic electrode and a counter electrode, and when a voltage is applied between both electrodes, the electrochromic electrode is cathodically reduced by ions from the electrolyte and electrons from a power source to be colored. It is a thing. The counter electrode, which is also composed of an electrochromic electrode, can be used for colored display. Alkali metal salts, alkaline earth metal salts, protonic acids and the like are used as solutes in the electrolyte solution of such electrochromic devices, and 1-phenyl-cyclopropanecarbonitrile, DL-2 phenylbutyronitrile, and solvents as solvents. Four
-Phenylbutyronitrile, 2,2 diphenylpropionitrile, polyethylene glycol dimethyl ether,
Polypropylene glycol dimethyl ether, propylene carbonate, γ-butyrolactone, etc. are used.

[0004]

In the electrochromic device using the electrolyte solution as described above, the light transmittance and the injected charge amount at the time of bleaching are not yet sufficient, and improvement of these is desired. Therefore, an object of the present invention is to provide an electrochromic device having improved light transmittance and amount of injected charges at the time of erasing, and a solid electrolyte membrane particularly useful for that purpose.

[0005]

DISCLOSURE OF THE INVENTION The present invention has made intensive efforts to achieve the above-mentioned object. As a result, by adding hydrogen peroxide to an electrolyte solution, the light transmittance and the injected charge at the time of bleaching of an electrochromic device. The present invention has been completed by finding that the amount can be improved. Thus, according to the present invention, in an electrochromic device in which an electrolyte layer is arranged between a substrate on which an electrochromic electrode and a counter electrode are formed, an electrolyte solution containing an electrolyte, an electrolyte solvent and hydrogen peroxide is used as the electrolyte layer. Provided is an electrochromic device characterized by the above, and a solid electrolyte membrane characterized in that the pores of a polymer porous membrane are filled with an electrolyte solution containing an electrolyte, an electrolyte solvent and hydrogen peroxide. .

The electrolyte solution is composed of an electrolyte (solute) and a solvent, and as the solute, for example, an alkali metal salt, an alkaline earth metal salt, a protonic acid or the like is used. Examples of the anions of these solutes include halogen ions, sulfate ions, phosphate ions, perchlorate ions, thiocyanate ions, trifluoromethanesulfonate ions, and borofluoride ions. Specific examples of the solute include lithium fluoride, lithium iodide, sodium iodide, lithium perchlorate, sodium thiocyanate, lithium trifluoromethanesulfonate, lithium borofluoride, lithium hexafluorophosphate, phosphoric acid, and sulfuric acid. , Trifluoromethanesulfonic acid, tetrafluoroethylenesulfonic acid, hexafluorobutanesulfonic acid, etc.
One kind may be used, or two or more kinds may be used in combination.

As the solvent of the electrolyte solution, in addition to the conventionally used solvents, any solvent that can dissolve the solute as described above can be used. For example, benzyl nitrile, benzyl cyanide, 1-phenyl- Cyclopropanecarbonitrile, DL-2 phenylbutyronitrile, 4-phenylbutyronitrile, 2,2 diphenylpropionitrile, polyethylene glycol dimethyl ether, polypropylene glycol dimethyl ether, propylene carbonate, γ-butyrolactone and the like can be used.

In the present invention, hydrogen peroxide is further added to the electrolyte solution composed of the above solute and solvent. The amount of hydrogen peroxide added varies slightly depending on the electrode used.
% Hydrogen peroxide solution, the effect of improving the light transmittance and the amount of injected charges at the time of erasing the color of the electrochromic device is preferably in the range of 0.1 to 6% by weight, more preferably 0.2 to 3.0% by weight. large.

This electrolyte solution may be used by injecting it into the electrochromic device panel as it is, but it is particularly effective when it is used as an electrolyte membrane by filling the pores of a solid polymer porous thin film. . The electrolyte membrane can be handled as a solid as a whole, there is no fear of liquid leakage, and the ion conductivity can be excellent. Also,
It has the advantage that it can be thinned.

Such a solid polymer porous thin film has a film thickness of 0.1 μm to 50 μm, a porosity of 40% to 90%, a breaking strength of 200 kg / cm ² or more, and an average through hole diameter of 0.001 μm.
Those having a thickness of up to 1.0 μm are preferably used. The thickness of the thin film is generally 0.1 μm to 50 μm, preferably 0.1 μm to
25 μm. If the thickness is less than 0.1 μm, it is difficult to put it into practical use from the viewpoint of deterioration of mechanical strength as a support film and handling. On the other hand, when it exceeds 50 μm, it is not preferable from the viewpoint of suppressing effective resistance. The porosity of the porous thin film should be 40% to 90%, preferably 60%.
% To 90%. If the porosity is less than 40%, the ionic conductivity as an electrolyte becomes insufficient, while if it exceeds 90%, the functional strength as a supporting film becomes small and it is difficult to put it to practical use.

The average diameter of the through holes is generally 0.001 μm to 1.0 μm, although it is sufficient if the ionic conductor can be fixed in the holes. The preferable average through-hole diameter depends on the material of the polymer film and the shape of the holes. The breaking strength of polymer membranes is generally 200 kg / cm ²
Above, more preferably 500 kg / cm ² or more, it is suitable for practical use as a supporting film. The porous thin film used in the present invention functions as a support for the above-mentioned ionic conductor and is made of a polymer material having excellent mechanical strength.

From the viewpoint of chemical stability, for example, polyolefin, polytetrafluoroethylene, or polypynylidene fluoride can be used, but from the viewpoint of designing the porous structure of the present invention and facilitating compatibility between thinning and mechanical strength. An example of a suitable polymer material is that the weight average molecular weight is 5 × 10 ⁵
The above-mentioned polyolefin. That is, it is a crystalline linear polyolefin of an olefin homopolymer or a copolymer, and has a weight average molecular weight of 5 × 10 ⁵ or more, preferably 1 × 10 ⁵ to 1 × 10 ⁷ .

Another example of a suitable polymer material is polycarbonate, in which case the solid polymer porous thin film is a polycarbonate thin film that is irradiated with charged particles in a nuclear reactor and alkali-etched by tracks that the charged particles pass through. It can also be manufactured by a method of forming a hole. Polycarbonate and polyester products such as Nuclepore membranes are commercially available as such thin films.

In addition, polyester, polymethacrylate, polyacetal, polyvinylidene chloride, tetrafluoropolyethylene and the like can be used. As a method for filling the electrolyte solution into the polymer thin film, a method of impregnating the solid polymer porous thin film with the electrolyte solution, coating or spraying, and using a solvent as necessary to remove after filling is used. be able to.

The electrochromic device is composed of a transparent substrate having an electrochromic electrode formed thereon,
The electrolyte solution is sealed between the transparent substrates on which the counter electrodes are formed, or in the case of an electrolyte membrane, this is sandwiched between the transparent substrates and sealed. A transparent electrode is formed as a collecting electrode between the electrochromic electrode and the transparent substrate. When the electrochromic element is of a reflective type, the substrate and / or the electrode on one side may not be transparent.

This electrochromic electrode is a reduction electrode.
Cathodic material to be colored and anodic dye to be oxidatively colored.
There are two types of materials. WO, which is a typical reducing coloring material
₃Then WO₃Is H from the electrolyte⁺(Li⁺) And power
When these electrons are injected, WO ₃(Colorless) + xH⁺+ Xe
= H_xWO₃The (blue) reaction is performed. This reaction is reversible
But H_xWO₃When the power circuit is opened in the state of
The blue color (reduced state) is retained for a long time. As a reducing colorant
Is WO₃Besides, IrO_x, MoO₃, MoS₂, V
₂O_Five, MgWO_Four, Nb₂O_Five, TiO₂, W_FourO₈
(C₂O_Four)_xEtc. can also be used. Electro
The chromic electrode has a thickness of about 500-10000Å,
This is formed on the transparent electrode.

The transparent electrode is a collector electrode and is made of indium oxide (ITO), tin oxide or the like. 1000 to 20 thickness
00Å is common. The transparent electrode is formed on a transparent substrate such as a glass plate. For the counter electrode, a material with a small amount of H ₂ and O ₃ generated and a good reversibility to an electrochemical redox reaction and a large electric capacity is used. Specifically, a metal oxide,
There are carbon, a composite material of a transition metal compound and carbon, a composite material of a metal oxide and carbon, and the like. The thickness of the counter electrode is about 1000Å-10 μm.

The counter electrode also has an electrochromic electrode.
 (Electrode II) can be provided, and Electrode I (WO₃) Return
In addition to the original coloring, the electrode II has an oxidation coloring material such as Ir.
O_x, Etc.
Device can be created. In addition, the electrode II has a different crystal state.
Naru WO₃May be used. Or NiO_x, Co
O _x, Prussian blue, polyaniline, etc.
It

An example of the structure of the electrochromic element thus constructed is shown in FIG. In the figure, 1 is an electrolyte membrane, 2 is an electrochromic electrode, 3
Is a transparent electrode, 4 is a transparent substrate, 5 is a counter electrode (transparent electrode), 6
Is a transparent substrate.

[0020]

[Example] ITO (indium oxide / tin oxide) was formed into a film of 1600 angstroms by ion plating 5
Ni-alkoxide toluene solution (1 mol / kg) on non-alkali glass of 0 mm square and 1.1 mm thickness, primary rotation speed 700 /
Spin coating at a secondary rotation speed of 1600 / min, heating to 350 ° C at a heating rate of 1 ° C / min, and holding for 3 hours at 1 ° C
The temperature was lowered to room temperature at a rate of 1 / min to obtain a nickel oxide electrochromic electrode having a thickness of 3400 angstroms.

ITO (indium oxide / tin oxide) was formed into a film with a thickness of 1600 angstroms by ion plating, and tungsten oxide (manufactured by Kojundo Chemical Co., Ltd.) was formed into a film with a thickness of 3000 angstroms on a 50 mm square 1.1 mm thick non-alkali glass. The film was formed to obtain a tungsten oxide electrode (electrochromic electric pole (2)). 2,2 diphenylpropionitrile 6 was added to a 25 micron thick polyethylene microporous membrane (porosity 56%) obtained by biaxial stretching.
An immobilized solution membrane electrolyte was manufactured by vacuum impregnation with an electrolyte solution (sample) consisting of 4.5 wt%, n-methylpyrrolidone 30 wt%, lithium perchlorate 5 wt%, and hydrogen peroxide 31% aqueous solution 0.5%.

An electrolyte of the sample was sandwiched between these electrodes and sealed with an epoxy adhesive to manufacture an electrochromic device. The cycle of applying a step voltage (10 seconds each) of minus 1.5 [v] and plus 0.2 [v] between the tungsten oxide electrode and the nickel oxide was performed 100 times, and then the coloring transmittance and the decoloring transmittance were measured. .

As a result, the transmittance and the haze ratio were changed as shown in Table 1 by adding a very small amount of aqueous hydrogen peroxide solution. For comparison, the transmittance and haze ratio of an electrochromic device using 65 wt% 2,2 diphenylpropionitrile, 30 wt% n-methylpyrrolidone, and 5 wt% lithium perchlorate electrolyte solution (sample) are shown. It was

Table 2 shows the sample of the electrolyte solution and the amount of injected charges when the sample was used. Table 1: Transmittance and haze rate of electrolyte solution containing 0.5% hydrogen peroxide aqueous solution Electrolyte solution transmittance T [%] Haze rate [%] Sample 62.4 2.8 Sample 55.9 3. 3 Table 2: Injection charge amount [ mC / cm ² ] of electrochromic device Sweep voltage Sample Sample -1.2V to + 0.2V 3.6 2.8 -1.3V to + 0.3V 3.9 3.3

[0025]

EFFECTS OF THE INVENTION According to the present invention, the addition of hydrogen peroxide improves the light transmittance of the electrolyte membrane, and when applied to the electrochromic device, the transmittance and the amount of injected charges at the time of erasing are improved. There is an effect that an electrochromic device is provided.

[Brief description of drawings]

FIG. 1 shows an example of the structure of an electrochromic device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electrolyte membrane 2 ... Electrochromic electrode 3 ... Transparent electrode 4 ... Transparent substrate 5 ... Counter electrode 6 ... Transparent substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoshi Sakurada 1-3-1 Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Tonen Corporation Research Institute

Claims (2)

[Claims] 1. An electrochromic device in which an electrolyte layer is provided between a substrate on which an electrochromic electrode and a substrate on which a counter electrode is formed are used, and an electrolyte solution containing an electrolyte, an electrolyte solvent and hydrogen peroxide is used as the electrolyte layer. An electrochromic device. 2. An electrolyte membrane obtained by filling the pores of a polymer porous membrane with an electrolyte solution containing an electrolyte, an electrolyte solvent and hydrogen peroxide.