JPH07128692A - Electrode and electrochemical element using that - Google Patents

Abstract

PURPOSE:To provide an electrode which can be used for a display element excellent in the cycle life of color changes and excellent in stability without causing retardation of response even when a solid electrolyte is used, and to provide an electrochemical display element having a fast response rate and excellent cycle life for color changes and stability. CONSTITUTION:This electrode consists of an electrode active material formed on a film or plate-type conductive substrate. The electrode active layer contains polyaniline or its deriv. and org. sulfonic acid. The org. sulfonic acid is selected from aliphatic sulfonic acids of 4-25 carbon number which may have halogen substituents, aromatic sulfonic acids of 6-30 carbon number which may include halogen, nitro groups, hydroxyl groups, alkyl groups of 4-25 carbon number, or alkoxy groups of 4-25 carbon number in the aromatic nuclei, camphorsulfonic acid, and sulfone phthalein dyes. This electrode is used for either or both of first and second electrodes of an electrochemical display element having a laminated structure comprising the first electrode 1, an electrolyte layer 3 and the second electrode 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode suitable as an electrode of a display element and an electrochemical display element using the electrode.

[0002]

2. Description of the Related Art Generally, a conductive polymer compound can be electrochemically doped / dedoped or oxidized / reduced. In recent years, this phenomenon has been utilized to convert a conductive polymer compound into a secondary battery. The use as electrode material is beginning to be implemented. Further, the conductive polymer compound causes a color change due to doping / dedoping or oxidation / reduction,
The possibility of application as a display material constituting a display element is also increasing. Furthermore, by using a solid electrolyte, it is possible to produce an all-solid-state secondary battery or display material, and many studies have been made on them. Electrochromic materials used for display elements have been found to be transition metal oxides such as tungsten oxide and molybdenum oxide, and organic substances such as viologen, but in general, conductive polymers are also polymers. It is an electrochromic material. When using these substances for display devices,
Usually, a display element having a layer structure as shown in FIG. 1 is manufactured. In FIG. 1, 1 is a first electrode, 2 is a second electrode, 3
Indicates an electrolyte layer, and the first electrode is a conductive substrate on which an electrochromic material layer is laminated, and by applying a voltage between both electrodes of the display element, coloring and erasing are performed. Is controlled.

However, in order to cause a color change in these electrochromic display elements, it is necessary to cause the electrochromic material to directly undergo oxidation / reduction reaction. This redox process is ideally a reversible process, but in reality there is the problem that side reactions such as decomposition of the electrochromic material are likely to occur, and therefore a short cycle life of coloring / decoloring is put to practical use. Has become a bottleneck. In particular, regarding polyaniline, Kobayashi et al. , Juro
nal of Electroanalytical
Chemistry, 161 (1984) 281 and I.S. Watanabe et al. , Macromo
A large number of research reports have been made, including Lecles, 20 (1987), 1793 and the like. However,
In the case of an electrochromic display device using polyaniline, when a solid electrolyte is used as the electrolyte, the response becomes slow and the cycle life is short, which is a problem.

[0004]

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems in the prior art. That is, an object of the present invention is to provide an electrode that makes it possible to construct a display element that does not have a slow response even when a solid electrolyte is used and has excellent cycle life and stability of color change. Another object of the present invention is to provide an electrochemical display element having a high response speed and excellent color change cycle life and stability.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventor has arranged a polyaniline compound and an organic sulfonic acid simultaneously on the surface of a film-like or plate-like conductive substrate. By using an electrode for at least one electrode of an electrochemical display element, it was found that the response is fast and the cycle of color change is very stable even when a solid electrolyte is used, and the present invention has been completed. .

That is, the electrode of the present invention comprises an electrode active material layer provided on the surface of a film-like or plate-like conductive substrate, and the electrode active material layer comprises polyaniline or a derivative thereof and an organic sulfone. It is characterized by containing an acid. Further, the electrochemical display element of the present invention has a laminated structure composed of a first electrode, an electrolyte layer, and a second electrode, and one or both of the first electrode and the second electrode is the electrode of claim 1. It is characterized by comprising the described electrode. In the present invention, as the organic sulfonic acid, an aliphatic sulfonic acid having 4 to 25 carbon atoms which may be substituted with halogen, a halogen, a nitro group, a hydroxyl group and a carbon number of 4 in the aromatic nucleus.
1 to 2 selected from an aromatic sulfonic acid having 6 to 30 carbon atoms, which may contain an alkyl group having 25 to 25 carbon atoms or an alkoxy group having 4 to 25 carbon atoms, camphor sulfonic acid, and a sulfonephthalein dye. It is preferable to use the above. The molar ratio of the nitrogen atom in the main chain of polyaniline or its derivative to the organic sulfonic acid is 1: 0.
It is preferably in the range of 20 to 1: 2.0.

The present invention will be described in detail below. The plate-shaped or film-shaped conductive substrate used in the electrode of the present invention is not particularly limited as long as it has conductivity, but is usually a metal plate, a metal foil, a metal fiber paper product, and a paper or film. ,
Examples thereof include those obtained by vapor-depositing a metal or a metal oxide on the surface of a glass plate or sintered glass. The metal to be vapor-deposited is usually gold, platinum, silver, copper, nickel,
A simple substance such as tin or aluminum or an alloy such as stainless steel or gold-tin is used. Further, as the metal oxide, indium oxide, tin oxide or the like can be used. As the vapor deposition method, an arbitrary method can be appropriately selected and used from known methods such as a vacuum vapor deposition method, a sputtering method, an ion plating method, and a CVD method.
When the electrode of the present invention is used as a display element, the conductive substrate is preferably colorless or white, such as glass or film deposited with platinum or metal oxide.

As the method for producing the electrode of the present invention, the following two methods are convenient and preferable because the electrode active material layer composed of polyaniline or its derivative and organic sulfone can be effectively formed. One of them uses a method of polymerizing aniline or a derivative thereof at a low temperature using an oxidizing agent to form polyaniline or a derivative thereof. As an example of the polymerization, persulfate such as ammonium persulfate, dichromate, permanganate, ferric chloride and the like are used as oxidants, and aniline or a derivative thereof at low temperature, for example, at -20 to 50 ° C. The soluble polyaniline is obtained by oxidative polymerization at a temperature in the range and treating this aniline-based oxidative polymer with aqueous ammonia. This soluble polyaniline has a number average molecular weight of 2,000-
It is preferably 500,000 [measured with GPC (N-methyl-2-pyrrolidone solvent), polystyrene-equivalent number average molecular weight]. The reason is that when the number average molecular weight of polyaniline is lower than 2,000, the strength of the electrode active material layer cannot be sufficiently obtained when it is formed, while when it exceeds 500,000, it is dissolved in a solvent. This is because the property becomes low, and it is not preferable in terms of processing for forming the electrode active material layer. The soluble polyaniline obtained as described above is soluble in amide solvents such as N-methyl-2-pyrrolidone or N, N-dimethylacetamide (DMAc), but other general-purpose organic solvents such as, for example, Almost insoluble in chloroform, chloroform and tetrahydrofuran. An appropriate solution of the desired organic sulfonic acid is added to this soluble polyaniline and stirred for 24 hours. This causes the polyaniline doped with organic sulfonic acid to dissolve. The solvent used here is not only an amide solvent such as NMP or DMAc in which the undoped polyaniline is dissolved, but also xylene, toluene, benzene, chlorobenzene, chloroform, dichloromethane, cresol,
It is possible to use general-purpose solvents such as nitromethane and tetrahydrofuran (AJ Heeger et al., Synthetic
Metals, (1992), 91-97). A solution containing a soluble polyaniline and an organic sulfonic acid obtained by using the latter general-purpose solvent is applied to a conductive substrate by casting or spin coating, and dried to easily obtain the electrode of the present invention. be able to.

The other is a method of electrolytically polymerizing aniline or a derivative thereof on a conductive substrate in the presence of a desired organic sulfonic acid. Aniline or a derivative thereof is used at a concentration of 0.1 to 2 mol / liter, together with a 2- to 10-fold excess of organic sulfonic acid, and water or an electrochemically inert solvent such as nitrobenzene, dimethyl sulfoxide, acetonitrile. , Propylene carbonate, etc., a desired conductive substrate is provided on the working electrode side, an inactive electrode such as platinum is provided on the counter electrode, and a voltage between 0.5 and 30 V is applied to electrolyze aniline or its derivative. Polymerize. Thereby, the electrode of the present invention can be obtained. Electropolymerization may be carried out by any method such as constant potential electrolysis, constant current electrolysis, and electrolysis by sweeping a periodic potential.
If necessary, the potential may be controlled by using the reference electrode. The polyaniline obtained by this method is often cross-linked, and its accurate molecular weight cannot be known, but it is sufficient if it does not dissolve in a solvent such as water, alcohol or acetonitrile. The film thickness of the electrode active material formed by the above method is generally 100 n.
It may be set in the range of m to 100,000 nm angstrom.

In any of the above methods, aniline or its derivative is used as a raw material. Specific examples of the derivative of aniline include o-toluidine and m-
Toluidine, o-anisidine, m-anisidine, 2,5
-Xylidine, 2,3-xylidine, 2-ethylaniline, 3-ethylaniline, 2-hydroxyaniline, 3
-Hydroxyaniline, N-methylaniline, N-ethylaniline, -propylaniline, N-butylaniline, N-pentylaniline, N-hexylaniline, N
Aromatic compounds having a primary or secondary amino group such as -octylaniline, N-decylaniline, N-dodecylaniline, N-docosylaniline, and diphenylamine can be given.

As the organic sulfonic acid, an aliphatic sulfonic acid having 4 to 25 carbon atoms which may be substituted with halogen, halogen, a nitro group, a hydroxyl group in an aromatic nucleus, an alkyl group having 4 to 25 carbon atoms, or One or more selected from aromatic sulfonic acids having 6 to 30 carbon atoms, which may contain an alkoxy group having 4 to 25 carbon atoms, camphor sulfonic acid, and sulfonephthalein dye are used. It Specifically, butane sulfonic acid, pentane sulfonic acid, hexane sulfonic acid, heptane sulfonic acid,
Aliphatic sulfonic acids such as octane sulfonic acid, pentadecafluorooctane sulfonic acid, decane sulfonic acid, dodecane sulfonic acid and halogen derivatives thereof; d-camphor-3-sulfonic acid, d-camphor-10-sulfonic acid, 1-camphor Camphorsulfonic acid such as -10-sulfonic acid, dl-camphor-10-sulfonic acid, d-camphor-8-sulfonic acid, dl-camphor-8-sulfonic acid; benzenesulfonic acid, toluenesulfonic acid, ethylbenzenesulfonic acid, Aromatic sulfonic acids such as dodecylbenzene sulfonic acid, chlorobenzene sulfonic acid, nitrotoluene sulfonic acid, cresol sulfonic acid, dinonylnaphthalene sulfonic acid; and cresol purple, cresol red, chlorophenol red, thymol blue Phenol red, bromocresol green, bromothymol blue, bromophenol blue, bromocresol purple, pyrogallol red, sulfone phthalein dyes such as pyrocatechol red, and the like.

The electrochemical display element of the present invention formed by using the above-mentioned electrodes basically has the layer structure shown in FIG. 1, but specifically, it has three layers shown in FIGS. 2 to 4. There are cases of morphology. 2 shows a structure using the electrode of the present invention for the coloring layer, and FIG. 3 shows a structure using the electrode of the present invention for the counter electrode of the electrochromic layer such as polyaniline or tungsten oxide.
FIG. 4 shows a structure in which the electrodes of the present invention are used for both electrodes.

In these electrochemical display elements, the electrolyte layer is not particularly limited in structure and type as long as it has sufficient ionic conductivity, and may be in the form of solution, gel or solid. I don't mind. When the electrolyte layer is composed of a solid electrolyte, it is composed of a matrix polymer and an electrolyte, and as the matrix polymer, those having a polyether main chain such as polyethylene oxide and polypropylene oxide, and siloxane and phosphazene having a polyether structure in the side chain. Polymers such as nitrile rubber and polymers such as nitrile rubber are generally used, and electrolytes include alkali metal perchlorates, alkali metal halides, sulfates, nitrates, sulfonates and the like, which are easily dissociated. Used.

The electrochromic layer in the case shown in FIG. 3 is, for example, a conductive substrate provided with a layer made of polyaniline, or a deposited film of a transition metal oxide such as tungsten oxide or molybdenum oxide. The thing formed etc. can be mentioned. The film thickness is generally 100 nm
It may be set to about 100,000 nm.

The electrochemical display device of the present invention can be manufactured by a method in which after preparing the above-mentioned electrodes, an electrolyte layer is provided on each electrode, and then the electrolyte layer is attached. When a solution or gel is used as the electrolyte layer, the electrochemical display element can be manufactured by a method of manufacturing the cell first, and then pouring the electrolyte between the electrodes and sealing.

Next, the display state when an electrochemical display element formed by using the electrode of the present invention is used will be described. In the electrochemical display element having the layer structure shown in FIG. 2, 1 to 1 is provided on the electrode (the portion surrounded by a thick frame) side of the present invention.
When a potential of about 3 V is applied, the green electrode changes to blue. When a potential of about 0 to -3 V is applied to the electrode side of the present invention, the blue electrode changes from green to yellow green. In the electrochemical display device having the layer structure shown in FIG. 3, it depends on the coloring condition of the electrochromic layer and cannot be generally stated, but 1 to 3 V is applied to the electrode (portion surrounded by a thick frame) of the present invention. When a potential of about 10 is applied, the green electrode changes to blue, so if the electrochromic layer on the counter electrode is colorless at this time, the electrochemical display element itself turns blue, and conversely the electrode side of the present invention. When a potential of 0 to -3V is applied to
Since the electrode exhibiting a blue color changes from green to yellow-green or colorless, it develops a color corresponding to the color on the counter electrode side (the color of the electrochromic layer if the electrode of the present invention is colorless). In addition, in the electrochemical display element having the layer structure shown in FIG. 4, when a potential of about 1 to 3 V is applied to the first electrode side, the electrode exhibiting green changes to blue and changes to green at 0 V. When returning to the negative potential, the second electrode develops more blue, so that the color change of green → blue → green → blue is possible. 2 to 4, PAn represents polyaniline.

[0017]

EXAMPLES The present invention will be described below with reference to examples. Example 1 4.1 g of aniline and 21.9 g of concentrated hydrochloric acid were dissolved in water to prepare 1
It was made up to 00 ml and cooled to -5 ° C. 21.9 g of concentrated hydrochloric acid and 6.28 g of ammonium persulfate were dissolved in water to give 10
The solution was cooled to -10 ° C, and the solution was slowly added dropwise to the aniline solution, and stirring was continued at -10 ° C for 6 hours. The produced solid matter was filtered, washed thoroughly with water, and then dedoped for 10 hours with 1N ammonia water. It was thoroughly dried. The number average molecular weight of this aniline oxidized polymer (hereinafter referred to as polyaniline) was 12,000 (measured in GPC and NMP, polystyrene equivalent number average molecular weight). 35 g of chloroform
0.18 g of dodecylbenzene sulfonic acid was dissolved in and the above polyaniline 0.1 g was further added to prepare a coating solution. Ratio of polyaniline and dodecylbenzenesulfonic acid dissolved in chloroform (depending on the molar ratio of dodecylbenzenesulfonic acid to nitrogen atoms of polyaniline)
Was calculated from the weight change before and after dedoping, and was 1:
It was confirmed to be 0.5. This solution is applied to ITO glass (Indium Tin Oxide vapor-deposited glass) and heated to 150 ° C.
And dried to form an electrode active material layer with a film thickness of 900 nm,
The electrode of the present invention was obtained.

Example 2 Instead of dodecylbenzenesulfonic acid in Example 1, d
An electrode of the present invention was prepared in the same manner using l-camphor-10-sulfonic acid. The molar ratio of dl-camphor-10-sulfonic acid to the nitrogen atom of polyaniline was determined from the weight change before and after dedoping, and it was confirmed to be 1: 0.9. Example 3 In an aqueous solution containing 0.1 mol / l of aniline and 0.5 mol / l of nitrotoluenesulfonic acid,
Using ITO glass as a working electrode and a platinum plate as a counter electrode, electrolytic polymerization was performed at a potential of 1 V for 20 seconds with respect to a saturated calomel electrode. This was lightly washed with water and dried at 100 ° C. to form an electrode active material layer having a film thickness of 10,000 nm. The molar ratio of nitrobenzenesulfonic acid to the nitrogen atom of polyaniline was calculated from the weight change before and after dedoping, and was 1:
It was confirmed to be 1.2. Example 4 An electrode of the present invention was prepared in the same manner as in Example 1 except that anisidine was used instead of aniline. The molar ratio of nitrobenzenesulfonic acid to the nitrogen atom of polyaniline was determined from the weight change before and after dedoping, and it was confirmed to be 1: 1.

In the following examples, an example of producing an electrochemical display element will be described. In Examples 5 to 11 and Comparative Examples 1 to 5, polyethylene oxide was used as the matrix polymer of the solid electrolyte, 0.22 mol of lithium perchlorate was added to 1 mol of ethylene oxide unit, and they were added to acetonitrile. A 2 wt% solution was prepared by dissolving, the obtained solution was applied to each of the first electrode and the second electrode, dried and then pressure-bonded to manufacture an electrochemical display element. Example 5 and Comparative Example 1 The electrode of Example 1 and the ITO glass were combined to produce the electrochemical display element of the present invention shown in FIG. For comparison, the electrode of Example 1 was immersed in 2N aqueous ammonia for 1 hour, and then completely removed from the aqueous solution of 10% hydrazine to prepare an electrode, which was combined with ITO in the same manner as above,
A conventional electrochemical display device was produced. (Comparative Example 1) 0V → + 2V → 0V on both ends of these display elements, respectively.
Square wave was applied every 2 seconds. All elements are green → blue →
Although the change in green color was repeated, the conventional electrochemical display element of Comparative Example 1 gradually lost contrast, and 10
It became blue and stopped changing after about 0 times. On the other hand, the electrochemical display element of the present invention could be changed up to 500 times.

Example 6 and Comparative Example 2 A conventional electrochemical display element for comparison with the electrochemical display element of the present invention (Comparative Example 2) using the electrode of Example 2 as in Example 5. Was produced. A rectangular wave of 0 V → + 2 V → 0 V was applied to both ends of each of these electrochemical display devices for a period of 2 seconds. All electrochemical display elements are green →
Although the change from blue to green was repeated, the conventional electrochemical display element gradually lost contrast, and after about 100 times, remained blue and did not change. On the contrary,
The electrochemical display element of the present invention could be changed up to 500 times.

Example 7 and Comparative Example 3 Using the electrode of Example 3, a conventional electrochemical display element for comparison with the electrochemical display element of the present invention (Comparative Example 3) was prepared in the same manner as in Example 5. Was produced. A rectangular wave of 0 V → + 2 V → 0 V was applied to both ends of each of these electrochemical display devices for a period of 2 seconds. All electrochemical display elements are green →
Although the change from blue to green was repeated, the conventional electrochemical display element gradually lost contrast, and after about 100 times, remained blue and did not change. On the contrary,
The electrochemical teaching element of the present invention could be changed up to 400 times.

Example 8 and Comparative Example 4 Using the electrode of Example 4, the conventional electrochemical display element for comparison with the electrochemical display element of the present invention (Comparative Example 4) was used in the same manner as in Example 5. Was produced. A rectangular wave of 0 V → + 2 V → 0 V was applied to both ends of each of these electrochemical display devices for a period of 2 seconds. All electrochemical display elements are green →
Although the change from blue to green was repeated, the conventional electrochemical display element gradually lost contrast, and after about 110 times, it remained blue and did not change. On the contrary,
The electrochemical display element of the present invention could be changed up to 550 times.

Example 9 and Comparative Example 5 The electrode of Example 1 was immersed in 2N aqueous ammonia for 1 hour, and then completely dedoped with a 10% hydrazicin aqueous solution to prepare an electrode. By combining the above, an electrochemical display element of the present invention having a layer structure shown in FIG. 3 was produced. On the other hand, for comparison purposes, the electrode of Example 1 was
An electrode was prepared by immersing in 2N aqueous ammonia for 1 hour and then completely undoped in a 10% hydrazicin aqueous solution, and similarly combined with ITO to prepare a conventional electrochemical display element (Comparative Example 5). A rectangular wave of 0 V → + 2 V → 0 V was applied to both ends of each of these electrochemical display devices for a period of 2 seconds. All electrochemical display elements repeatedly changed from green to blue to green, but the conventional electrochemical display elements
The contrast gradually disappeared, and after about 100 times, it became blue and remained unchanged. On the other hand, the electrochemical display element of the present invention was able to obtain sufficient contrast up to 2,500 times and to stably change the color.

Example 10 Two electrodes of Example 1 were combined to produce an electrochemical display element of the present invention having the layer structure shown in FIG. 0V → + 2V → 0V → −2 at both ends of these display elements, respectively.
A rectangular wave of V → 0 V was applied in a cycle of 4 seconds. In response to this application condition, change green → blue → green → blue → green by 10,000
It was repeated 0 times or more, but sufficient contrast was obtained and stable color change was possible.

Example 11 Two electrodes of Example 2 were combined to produce an electrochemical display element of the present invention having the layer structure shown in FIG. 0V → + 2V → 0V → -2V → 0V on both ends of these display elements
Square wave was applied for a period of 4 seconds. Corresponding to this application condition, the change of green → blue → green → blue → green was repeated 10,000 times or more, but sufficient contrast was obtained and stable color change was possible.

[0026]

The electrode of the present invention comprises a film-like or plate-like conductive substrate provided with an electrode active material layer containing polyaniline or a derivative thereof and an organic sulfonic acid on the surface thereof, so that the coloring / decoloring cycle is extremely effective. It is stable and very useful as an electrode for display devices. Further, the electrochemical display element of the present invention formed by using this electrode has a fast response even when a solid electrolyte is used as an electrolyte layer, has a very stable coloring / decoloring cycle, and has a long life. It has excellent properties.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an electrochemical display device.

FIG. 2 is a diagram showing a layer structure of an example of an electrochemical display device using the electrode of the present invention.

FIG. 3 is a diagram showing a layer structure of another example of the electrochemical display device using the electrode of the present invention.

FIG. 4 is a diagram showing a layer structure of still another example of the electrochemical display device using the electrode of the present invention.

[Explanation of symbols]

 1 ... 1st electrode, 2 ... 2nd electrode, 3 ... electrolyte layer.

Claims (4)

[Claims] 1. An electrode comprising an electrode active material layer provided on the surface of a film-shaped or plate-shaped conductive substrate, wherein the electrode active material layer contains polyaniline or a derivative thereof and an organic sulfonic acid. And the electrode. 2. The organic sulfonic acid is an aliphatic sulfonic acid having 4 to 25 carbon atoms which may be substituted with halogen, a halogen, a nitro group, a hydroxyl group, an alkyl group having 4 to 25 carbon atoms or a carbon atom in the aromatic nucleus. Characterized by comprising one or more selected from aromatic sulfonic acids having 6 to 30 carbon atoms, which may contain an alkoxy group having 4 to 25 carbon atoms, camphor sulfonic acid, and sulfonephthalein dye. The electrode according to claim 1. 3. The molar ratio of the nitrogen atom in the main chain of polyaniline or its derivative to the organic sulfonic acid is 1: 0.20.
The electrode according to claim 1, wherein the electrode has a ratio of 1: 2.0. 4. An electrochemical display element having a laminated structure composed of a first electrode, an electrolyte layer and a second electrode, wherein either one or both of the first electrode and the second electrode is provided.
An electrochemical display element comprising the described electrode.