JPH0367227A - Electrochromic element - Google Patents

Abstract

PURPOSE:To obtain the ECD having a solid-state electrolyte of a high ion conductivity by using the thin film of the electrolyte formed by filling an ion conductor into the pores of the porous thin film of a solid-state high polymer as the electrolyte. CONSTITUTION:The thin film of the electrolyte formed by filling the ion conductor into the pores of the porous thin film of the solid-state high polymer is used as the electrolyte. The porous thin film to be used consists of a high- polymer material which has a function as the base of the ion conductor and has excellent mechanical strength. For example, polyolefin, polytetrafluoroethylene and polyvinylidene fluoride are usable in terms of chemical stability. The electrochromic element (ECD) having the solid-state electrolyte of the high ion conductivity is obtd. in this way.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an electrochromic device.

More specifically, the present invention relates to an electrochromic device using a porous polymer thin film whose pores are filled with an ionic conductor as an electrolyte.

[Conventional technology]

There is growing interest in devices that apply the electrochromic (EC) phenomenon, in which the color of a material changes reversibly depending on voltage. Electrochromic devices (ECDs) are bright and easy to see, can display large areas, and have memory properties.
It has features such as low power consumption, and applications that take advantage of these features include stock price displays, message boards,
These include large display boards such as information boards, and light control elements for automobile anti-glare mirrors, light control glass (windows), and sunglasses.

The structure of ECD consists of an electrolyte placed between an electrochromic electrode (WOs) and a counter electrode, and when a voltage is applied between both electrodes, 1103 is cathodically reduced with ions from the electrolyte and electrons from the power source, and becomes colored. be. The opposite is
This can also be configured with electrochromic electrodes and used for colored display.

[Problem to be solved by the invention]

Electrolytes are divided into liquid electrolytes and solid electrolytes. A liquid electrolyte has high ionic conductivity and therefore has excellent responsiveness, but it is undesirable for liquid to enter the element from a structural standpoint. Due to the structure and assembly of the element, measures against liquid leakage are required, and even if measures against liquid leakage are taken, there is no guarantee that liquid leakage will not occur due to damage or during use, and if liquid leakage occurs, it may cause staining of surrounding parts etc. There are also problems. Solid electrolytes do not pose any problems when handling such liquids, but there is a problem of poor responsiveness because there is no solid electrolyte with high ionic conductivity.

Therefore, an object of the present invention is to provide an ECD having a solid electrolyte with high ionic conductivity.

[Means to solve the problem]

In order to achieve the above object, the present invention provides an electrochromic device characterized in that an electrolyte thin film formed by filling the pores of a solid polymer porous thin film with an ionic conductor is used as an electrolyte. .

The electrolyte used in the present invention consists of an electrolyte thin film formed by charging an ionic conductor into the pores of a solid polymer porous thin film. This electrolyte thin film can be handled as a solid as a whole, there is no fear of liquid leakage, and it has excellent ionic conductivity.

Further, it is possible to make the film thinner.

Such a solid polymer porous thin film has a film thickness of 0.
1JBa~50-1 Porosity is 40%~90%, Breaking strength is 200kg/cI11 or more, Average through hole diameter is 0.00
Those having a diameter of 1 Js to 0.7 μ are preferably used.

The thickness of the thin film is generally 0.1 to 50 mm, preferably 0.1 square to 251 mm. If the thickness is less than 0.1 μm, it is difficult to put it to practical use because of the reduced mechanical strength as a support film and the ease of handling. On the other hand, if it exceeds 50-, it is not preferable from the viewpoint of keeping the effective resistance low. The porosity of the porous thin film is preferably in the range of 40% to 90%, preferably in the range of 60% to 90%. If the porosity is less than 40%, the ionic conductivity as an electrolyte will be insufficient, while if it exceeds 90%, the functional strength as a support membrane will be low, making it difficult to put it into practical use.

The average diameter of the through-holes is generally between 0.001 and 0.7, although it is sufficient that the ionic conductor can be immobilized in the holes. The preferred average through-hole diameter depends on the material of the polymer membrane and the shape of the pores. The breaking strength of the polymer membrane is generally 200 kg/cff1 or more, more preferably 500 kg/c++! Having the above properties makes it suitable for practical use as a support membrane.

The porous thin film used in the present invention functions as a support for the ion conductor as described above, and is made of a polymeric material with excellent mechanical strength.

From the viewpoint of chemical stability, for example, polyolefin, polytetrafluoroethylene, and polyvinylidene fluoride can be used, but they are preferred from the viewpoint of designing the porous structure of the present invention and the ease of achieving both thinning and mechanical strength. An example of such a polymeric material is a polyolefin having a weight average molecular weight of 5 XIO' or more. That is, a crystalline linear polyolefin, which is an olefin homopolymer or copolymer,
Its weight average molecular weight is 5X10' or more, preferably 1X
1011 to IX1.0'. Examples include polyethylene, polypropylene, ethylene-propylene copolymer, polybutene-1, poly-4-methylpentyne-1, and the like. Among these, the weight average molecular weight is 5X
Polyethylene or polypropylene of 10' or more is preferred. The weight average molecular weight of the polyolefin influences the mechanical strength of the resulting permeable membrane. Ultra-high molecular weight polyolefins enable the formation of ultra-thin and high-strength films by ultra-stretching, and are used as supports for highly ionic conductive thin films with low effective resistance. Although a polyolefin having a weight average molecular weight of less than 5 x 10 5 can be used at the same time, an ultra-thin and high strength film cannot be obtained by ultra-stretching in a system that does not contain a polyolefin having a weight average molecular weight of 5 x 10 5 or more.

The porous thin film as described above can be manufactured by the following method. Ultra-high molecular weight polyolefin is heated and dissolved in a solvent such as liquid paraffin in an amount of 1% to 15% by weight to form a uniform solution. A sheet is formed from this solution and rapidly cooled to form a gel-like sheet. The amount of solvent contained in this gel-like sheet is extracted with a volatile solvent such as methylene chloride.
0% to 90% by weight. This gel-like sheet is heated at a temperature below the melting point of the polyolefin and stretched to an areal magnification of 10 times or more. The solvent contained in this stretched film is extracted and removed with a volatile solvent such as methylene chloride, and then dried.

Another example of a suitable polymeric material is polycarbonate, in which the solid polymer porous thin film is made by irradiating the polycarbonate thin film with charged particles in a nuclear reactor and etching the tracks of the charged particles with alkali to form pores. It can also be produced by a method of forming. Such membranes are coated with polycarbonate and polyester products, for example as nucleopore membranes.

In addition, polyester, polymethacrylate, polyacetal, polyvinylidene chloride, tetrafluoropolyethylene, etc. can be used.

The ionic conductor used in the present invention is a composite of an alkali metal salt or protonic acid and a polar polymer such as polyether, polyester, or polyimine, or a network or crosslinked polymer containing these polymers as segments. Complexes with molecules can be used. polyether,
For example, polyethylene glycol, polypropylene glycol, or their copolymers are commercially available as liquid and powder reagents with different molecular weights and degrees of polymerization.
It can be used easily. That is, polyethylene glycol, polyethylene glycol monoether, polyethylene glycol diether, polypropylene glycol, polypropylene glycol monoether,
Polyethers such as polypropylene glycol diether, or copolymers of these polyethers such as poly(oxyethylene/oxypropylene) glycol, poly(oxyethylene/oxypropylene) glycol monoether, or poly(oxyethylene)・
Oxypropylene> glycol diether, condensates of these polyoxyalkylenes and ethylenediamine, phosphoric acid esters, saturated fatty acids, aromatic esters, etc. can be used. Furthermore, copolymers of polyethylene glycol and dialkylsiloxane (for example, Arusse et al., Polymer Preprints, Japan
Vol, 34. No, 7.2021-2024 (
1985), and Japanese Patent Application Laid-Open No. 60-217263)
, copolymers of polyethylene glycol and maleic anhydride (e.g. C, C, Lee et al., Polymer, 198
2. Vol.

23 May 681-689), and copolymers of monomethyl ether of polyethylene glycol and methacrylic acid (e.g. N, Kobayashi et al., J. Ph.
ysical Chem-istry, Vol, 89
．． No. 6.98'7-991 (1985)) are known to form complexes with alkali metal ions and have ionic conductivities of 10-5 to 10-'S-cm-' at room temperature. Therefore, it is suitable as a material constituting the thin film electrolyte useful in the present invention.

The above-mentioned polyethers may have a low molecular weight of 150 or more, and the above-mentioned polymers include boopylene carbonate, T-butyrolactone, ethylene carbonate,
One or more of the following solvents may be added: methylfuran, dimethoxyethane, dioxolane, tetrahydrofuran, acetonitrile, dimethylformamide, dimethylsulfoxide, methyltetrahydrofuran, sulfolane, methylthiophene, methylthiazonopethoxymethoxyethane. .

An alkali metal or alkaline earth metal salt or a protonic acid can be used to form a complex with these polymer compounds. Examples of anions include halogen ions, perchlorate ions, thiocyanate ions, trifluoromethanesulfonate ions, and borofluoride ions. Lithium fluoride (LiF), sodium iodide (
Nal), lithium iodide (Lil), lithium perchlorate (LtCj!DJ), sodium thiocyanate (
NaSCN),) Lithium methanesulfonate (LICF+5Os), Lithium borofluoride (LIB)
F4), lithium hexafluorophosphate (L+PFs)
, phosphoric acid (H, PO3), sulfuric acid (H2SO1), trifluorinated methanesulfonic acid, tetrafluorinated ethylene sulfonic acid CCaF4 (SO3M) 2 ''J, hexafluorinated butanesulfonic acid CC4F6 (SO3M)4
), etc. can be cited as specific examples.

As a method of filling ionic conductors into a polymer thin film,
■Remove the solvent after impregnating, coating or spraying an ionic conductor dissolved in a solvent, or an ionic conductor finely dispersed in a solvent in the form of a sol or gel, into a solid polymer porous thin film;■ In the porous thin film manufacturing process, a film is formed after mixing a solution of an ionic conductor or its sol or gel-like dispersion solution. ■ Impregnation of a monomer or soluble precursor of an ionic conductor into a solid polymer porous thin film. Do you want me to do it?
A method such as applying or spraying and then reacting within the pores can be used.

The electrochromic device of the present invention is a general device, except that the solid electrolyte thin film as described above is used as the electrolyte.
In particular, it can be similar to ECD using a solid electrolyte.

[For production]

In the ECD of the present invention, the electrolyte is at an ambient temperature, for example, -10
Because it has sufficient ionic conductivity at ℃~30℃,
It has a wide operating temperature range and is easy to assemble and handle because the electrolyte is a flexible solid thin film.

Therefore, it is possible to easily provide elements with no liquid leakage, uniform thickness, and large area, and various shapes can be selected. Suitable for use.

〔Example〕

Examples will be described using the drawings.

FIG. 1 shows an example of an EC display element. In this laminated structure, from the bottom, there are a glass plate 1, a counter electrode 2, a background plate 3, a solid electrolyte thin film 4, an ECN pole 5, a transparent conductive film 6, and a glass plate 7. Since this EC display element is in a reflection mode, the glass plate 1 does not necessarily have to be a transparent body, and may also be a resin plate or the like. For the counter electrode 2, a material that generates less H2,02, has good reversibility with respect to electrochemical redox reactions, and has a large capacitance is used. Specific examples include carbon, a composite material of a transition metal compound and carbon, or a composite material of a metal oxide and carbon. The thickness of the opposite pole 2 is 1000 people ~
10t! It is about rn. The background plate 3 is generally a white background material, and for example, a sheet formed by kneading alumina powder with a binder may be used. The background plate 3 can also serve as the counter electrode 2.

As the solid electrolyte thin film 4, for example, one prepared as described below is used. For example, in a polyethylene microporous membrane,
It is made by impregnating polyethylene glycol monoether with an electrolyte solution in which lithium trifluoromethanesulfonate as an electrolyte is dissolved, and has a thickness of 4 pm and an ionic conductivity of 2xlO-'S/cm.

There are two types of ECN electrodes 5, a cathodic material that is colored by reduction and an anodic material that is colored by oxidation, but here, WO, which is a typical reducing coloring material, is used. When WO, is injected with H′″ (Li”) from the electrolyte and electrons from the power source, WO3 (transparent) ++<H”+xe=HxWO
Perform the reaction s (blue). Although this reaction is reversible, when the power supply circuit is opened in the state of H and WO3, the blue color (reduced state) is maintained for a long time. As a reduction colorant, WO
, as well as IrOx, Mob, , MoS2. V
,0. .

MgWO, Nb, 05. Tin□, LOs(c,
o, ), etc. can also be used. EC electrode 5 is 50
This is formed on the transparent conductive film 6 to a thickness of about 0 to 1,500.

The transparent conductive film 6 is a current collecting electrode and is made of indium tin oxide (I
TO), tin oxide, etc. Thickness is 1000~2
000 people is common. A transparent conductive film 6 is formed on a glass plate 7.

Since the glass plate 7 is in reflection mode, it must be transparent.

A voltage is applied from the power supply 8 between the EC electrode 5 and the counter electrode 2, but a negative voltage is applied to l803 during reduction, and the voltage is 1.
It is about 3 to 1.6V.

Since the electrolyte of the ECD produced in this way is solid,
It has a simple structure, is easy to handle during assembly, and there is no need to take special precautions as in the case of liquid electrolytes, as there is no risk of liquid leakage even if the electrolyte is damaged even after assembly. Furthermore, when a voltage is applied between the electrodes from a power source, a display with excellent responsiveness can be realized.

FIG. 2 shows an example of an EC dimming element (window). From the bottom: glass plate 11, transparent conductive film 12, electrode 13, electrolyte membrane 14, electrode 115, transparent conductive film 16, and glass plate 1
It has a laminated structure in the order of 7. In this structure, electrode I (WO
In addition to the reduction coloring described in 3), if an electrode material with an oxidative coloring amount, such as Ire, is used for electrode (2), E with high coloring efficiency can be obtained.
It has the feature of being able to create CDs. Furthermore, WOs having different crystal states may be used for the electrode (2). or NiOx,
C00X, KxFe [Fe(CN)a].

[:]e(CN)sco] etc. are used.

The structure in FIG. 2 is different from that in FIG.
The electrode [13] and the transparent conductive film 11 are formed to have a thickness of a human being and are transparent to light. In the structure shown in FIG. 3, the background plate 3 is light-opaque, and the counter electrode 2 may be light-opaque or light-transmissive.

In the structure shown in FIG. 2, a voltage is applied between both electrodes to
When colored (and electrode l115), this ECD acts as a light control glass (EC window). In this structure, if the electrode 113 (electrode 15) is patterned, it can also be used as a transmissive display element.

Further, in the anti-glare mirror, the background plate 3° and the counter electrode 2 in FIG. 1 are made of reflective electrodes, such as aluminum.

In the ECD having the structure shown in FIGS. 1 and 2, the reflectance and transmittance of incident light in the display mode are 20 to 70%, and the durability is 104 to 107 times.

〔Effect of the invention〕

According to the present invention, an ECD using a solid thin film electrolyte is provided, and since this ECD does not require measures against liquid leakage, it is excellent in handling and safety, and the responsiveness of the ECD is also improved.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a reflective EC display element, and FIG. 2 is a schematic sectional view of a transmission type light control glass. 1...Glass plate, 2...Counter electrode, 3...
Background plate, 4... solid electrolyte thin film, 5...
EC electrode (1103), 6... transparent conductive film, 7...
・Glass plate, 11... Glass plate, 12... Transparent conductive film, 13... Electrode ■, 14... Solid electrolyte thin film, 15... Electrode ■, 16... Transparent conductive film,
17...Glass plate. ECD element (display element) 1st discontinuation procedure amendment sound (method) % formula % 1. Indication of the case 1990 Patent Application No. 48490 2. Name of the invention Electrochromic device 3. Person making the amendment Relationship with the case Patent Applicant name: Tonen Corporation 4, agent address: Toranomon-8-1o EC, Minato-ku, Tokyo 105
D element (dimmer element) No. 2, Section 6, Subject of amendment (1) Specification (2) Power of attorney 7, Contents of amendment (1) Engraving of specification (no change in content) (2) Pursuing power of attorney do. 8. List of attached documents (1) Copied detailed statement (2) 1 power of attorney 236-

Claims (1)

[Scope of Claims] 1. An electrochromic device characterized in that an electrolyte thin film formed by filling the pores of a solid polymer porous thin film with an ionic conductor is used as an electrolyte. 2. The electrochromic device according to claim 1, which is a display device. 3. The electrochromic device according to claim 1, which is a light control device.