JPS60263923A - Electrochromic display element - Google Patents

Abstract

PURPOSE:To realize lowering of drive voltage and speed-up of response and to prevent deterioration of function in a dry state by adding a sulfonated styrene polymer as a binder to a specified inorg. proton conductor powder to form a solid-state electrolyte layer. CONSTITUTION:A transparent electrode is attached to a transparent base made of glass or the like, and on this layer an electrochromic layer 4 made of, e.g., WO3, colorable, decolorable, or discolorable reversibly by electrochemical reduction and oxidation is formed. The intended electrochromic display element can be obtained by adding the polymer of sulfonated styrene expressed by the formula as a binder into an inorg. powder high in proton conductivity, selected from a hydronium-substd. type beta''-alumina and antimony oxide hydrate and tin oxide hydrate, and coating said layer with the coating soln. obtd. by above-mentioned way to form a solid-state electrolyte layer.

Description

[Detailed description of the invention] [Technical field of invention] This invention develops color by electrochemical reduction and oxidation.

The present invention relates to a so-called electrochromic display element that performs a dynamic display by decoloring or changing color, and more specifically relates to a solid electrolyte thereof.

[Technical honors of inventions and their problems]

Electrochromic display devices (ECDs) are display devices that reversibly change color through electrochemical oxidation and reduction, and have low visual dependence and easy-to-read memory. It is expected because of its merits such as: Materials that develop, fade or change color (EC
Various materials are known as HCD materials, but in order to electrochemically oxidize or reduce these EC materials, HCDs are usually made of electrolyte materials that have only ionic conductivity and low electronic conductivity. is placed in contact with the EC material. Examples of such an electrolyte using a liquid such as dilute sulfuric acid or propylene carbonate in which lithium perchlorate is dissolved are known, but in consideration of ease of assembly, reliability, etc., it is desirable to use a solid electrolyte. As a mobile ion in a solid electrolyte, EC
Considering the ease of diffusion in the material, protons (H)
is often desirable. As a conventional proton conductive solid electrolyte, li Z r OH + M gFt + Ca
Vapor deposited films such as Ft p S s Ot are known. These materials do not originally need to contain 11+ as a constituent element (O2 is considered to be an ionic conductive, electronic conductive, or insulating material.The mechanism by which these materials transport H+ has not been fully elucidated). Although it is difficult to say that it is deposited microscopically, it is deposited as a porous material with many pores, and during or after the deposition process, moisture contained in the surrounding atmosphere is adsorbed to the pore walls, and this adsorbed It is believed that moisture enables the transport of 10H5.

We actually produced an ECD using these vapor deposited films as electrolytes,
When operated, it operates satisfactorily in a high humidity atmosphere during the summer, but loses its ability in a short period of time in dry conditions (for example, relative humidity of 10% or less). This is probably due to the detachment of the adsorbed moisture mentioned above. Thus, the above-mentioned vapor deposited film (commonly and customarily referred to as a dielectric film) has the disadvantage that its performance decreases and is eventually lost in a dry state. On the other hand, inorganic crystal proton conductors such as hydronium (HsO) substituted β-alumina are known. These contain water molecules (H2O) in their crystal structures, and are stable when dried at room temperature, but cannot be made into thin films by techniques such as vapor deposition and sputtering.

[Purpose of the invention]

An object of the present invention is to provide an electrochromic display element using a solid model proton conductive electrolyte for ECD that functions satisfactorily even in the dry state as described above.

[Summary of the invention]

The present invention can be applied to hydronium-substituted β-alumina, hydronium-substituted β'-alumina, and antimony oxide-containing hydrated tin oxide, which have relatively high proton conductivity but are difficult to use in ECD because they are difficult to form into conventional membranes. When inorganic materials such as hydrated salts lose their electrical conductivity (EC
This is an electrochromic display element used as a proton conductive solid electrolyte membrane for D.

These hydrated salts are usually obtained in the form of powder, but even if such powder is formed into a layer as it is, only a small electrical conductivity can be obtained compared to the proton electrical conductivity inside the crystal.

This is because in such a powder aggregate, sufficient contact cannot be obtained between each crystal grain, and large voids are present. If such voids can be filled with a proton conductive material, ion conductivity will be improved. In this case, the higher the proton conductivity, the more desirable it is, but even if the conductivity is slightly lower than that of each crystal grain, a considerable effect can be expected compared to the case where it has no conductivity at all. The present invention is designed to fill such voids and to deposit the granules in a mechanical fusing process.
The main idea is to use a binder that is both strong and proton conductive to obtain a hybrid proton conductive membrane.

As an inorganic proton conductive material, hydronium-substituted β
At least one of alumina, hydronium-substituted β″ alumina, and hydrated antimony oxide and tin oxide hydrate was used,
Any hydrated crystal with high proton conductivity may be used. On the other hand, although various resins have been tried as the binder resin, even if some of the styrene is not oxidized with sulfone, the basic gist of the present invention is not impaired.
There is no problem even if there is some crosslinking polymerization between polymer chains as long as it can be dissolved in a suitable solvent.

Since the sulfonated styrene polymer can be dissolved in water or other polar solvents, a powder of proton conductive water-containing crystals is suspended in the solution, coated on the material, and dried. In this case, in order to ensure sufficient contact between the crystal grains and the polymer and to ensure uniform dispersion in the solvent, adding dispersants, surfactants, etc. is not a problem as long as it does not adversely affect the physical properties of the crystal grains or polymer. .

〔Effect of the invention〕

By using the high grid membrane of the present invention, the driving voltage of the ECD was lower and the response time was faster than when using the sulfonated styrene polymer alone.

[Embodiments of the invention]

MgO-stabilized Naβ' alumina with an average particle size of 15 μm was placed in concentrated sulfuric acid, heated at 240°C for 40 hours, and poured into a large amount of cold water to obtain H,0+ substituted β' alumina. It was then ground in a ball mill to give an average particle size of 0.9 μm.To 32 f of this powder, 2.5 l of sulfonated styrene polymer was added, and 100 m/m of water was added and thoroughly stirred to obtain a white suspension. This liquid was applied to a glass substrate (: I
T ON! i, WO, and a vapor-deposited layer (thickness: 2000) and coated on top to obtain a layer with a thickness of 1.5 μm.

On top of this, a layer of 5 WO (thickness: 2000 Å) was further provided, and finally, 500 OA of gold was deposited.

On the other hand, for comparison, T(,O-substituted β' alumina was used).
0.7μ using only sulfonated styrene polymer
A sample having the same configuration as the example was prepared, except that a film of m was provided between the WO5 layers.

When applying these C double pressures and examining the characteristics as an ECD, the example exhibited color development and fading within ±2.5 square meters, and the response time was 150 cm.
m5ec, comparative example is ±3v and response time is 500m5ec
Met.

il) K, H, Sb, 07 ・4H, 0wo5 N
After treatment in O nitric acid for U hours, H8 of pyrochlore-type crystals was obtained.
bO,xH,0 (x=l) was obtained. This was thoroughly washed with water and then pulverized in a ball mill to obtain a powder with a particle size of 0.9 μm.

This was suspended in water in which a sulfonated styrene polymer was dissolved in the same manner as β" alumina in Example 1. The mixing ratio was the same as in Example 1. Discolored response time Lt 200 mse
It was c.

Claims (1)

[Scope of Claims] A layer that reversibly develops, decolors, or changes color when electrochemical reduction or oxidation≦2 is provided on a transparent electrode, and a layer of hydronium-substituted β-alumina or hydronium-substituted β'-alumina is provided on this layer. , antimony oxide hydrate (s b. 0, .4H20), tin oxide hydrate (8nO, .3H
An electrochromic display element characterized in that a layer is provided in which a sulfonated styrene polymer is added as an inder to a powder of an inorganic proton conductor consisting of at least one of the following.