JPS6057574B2 - Method of manufacturing electrochromic electrodes - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an electrochromic (hereinafter abbreviated as EC) electrode.

Conventionally, WO3 and Ti0 have been used as EC display bodies.

Although solid EC (e.g., solid EC) or organic viologen compounds are known, elution from the electrode has been a problem with the former, and adhesion of redox substances to the surface has been a problem with the latter. During research on hydrogen and oxygen adsorption on iridium electrodes, the present inventor discovered that the color of iridium electrodes changed.
This was reported at the Summer Meeting of the Electrochemical Society. There is a report that attempts to use this color change of the iridium electrode as an EC display. The present inventor discovered that an electrode exhibiting the EC properties of an iridium electrode is produced by hydrogen and oxygen adsorption/desorption reactions of an iridium electrode. That is, the lower limit potential +O, 4V (vs, R
HE) Hydrogen adsorption or generation region below, upper limit potential +1.0
It has been discovered that EC electrodes can only be produced by continuous sweeps between the oxygen adsorption region from V to +1.70V. FIG. 1 shows an electrochemical cell used in the present invention, which is made of Pyrex glass.

In FIG. 1, 1 is an iridium metal wire, 2 is a platinum counter electrode, 3 is a platinum electrode for a reference electrode, and 4 is 1 atm Ho gas. 5 is a 1NH2S04 aqueous solution.

Such a cell was driven using a device as shown in FIG. 6
is a potentiostat, 7 is a function generator, and 8 is a synchronoscope.

FIG. 3 shows a continuous sweep waveform applied to the cell at a sweep rate of O and 1 VI sec.

Vmin■50wl, ri (vs, m positive), Vmax 1
．． FIG. 4 shows the sweep current response of the iridium electrode when the voltage is 4V (vs, RHE). This was observed using a synchroscope 8. A is a hydrogen desorption reaction, B is a current value indicating an oxygen adsorption reaction, B' is an oxygen desorption reaction, and A' is a hydrogen adsorption reaction. As the number of sweeps N increases, the portions B and B' increase significantly. On the other hand, A and A' are constant. Since the area (charge amount) of A is constant, the amount of increase in B at this time is plotted against the number of sweeps in FIG. 6. In addition, the B/A behavior with Vmin 50771 and Vmax changed at V-constant is also shown. From this figure, V
max■1, Electrode coating B exhibiting EC properties unless it is OV or more
It became clear that no growth occurred.

On the other hand, at 1.7 V or more, the coating was eluted and the liquid showed a purple color. Moreover, such film formation did not occur when the potential was maintained at a constant level. FIG. 6 shows the change in B/A when Vmax is fixed at 1.4V and Vmin is varied. It is clear that such film growth does not occur unless Vmin is 0.4 V or less. For this reason, the manufacturing conditions for EC electrodes are lower limit potential of 0.4■ or less and upper limit potential of 0.4. It is 0V or less and 1.7V or less. The present invention claims such potential conditions for manufacturing EC electrodes. Such an iridium electrode turns black after being swept several thousand times. Thereafter, by performing a sweep of 1V1sec, it is possible to manufacture an iridium EC electrode that can change or display a metallic color of iridium in the cathodic process and black in the anodizing process.

Similarly, Pt. ．． Ru. ．． RhlPd. It can also be manufactured using an Os noble metal electrode. Although the results of triangular wave sweep are shown here, similar results were also observed with rectangular waves, wedge waves, etc., or a combination thereof. The same thing happened with acids other than sulfuric acid, neutral salts, and alkalis. An EC display using the present invention will be described below according to Examples. Example 1 400-500A was deposited on a 4-digit 7-segment type tin sensor formed on a glass substrate by EB vacuum evaporation.
coated with iridium.

Such an electrode in a 1N sulfuric acid solution at Vmax=1.5V
、． Vmin=50wL, V1 sweep speed 10V1sec
A continuous triangular wave sweep of 1Cg was performed 5 times. The iridium surface became a black film. A cell was assembled using such an electrode and a platinum-coated glass substrate as a counter electrode. When the cells were filled with an electrolytic solution of glycerin/H2SO4=1:1 and a 0.5 V rectangular wave was applied between the two electrodes, the iridium EC electrode became transparent at the cathode stage and black at the anode stage. In other words, erasing was performed during the cathode process, and writing was performed during the anode process. The response speed at this time was 50rrLsec, and the contrast was 1:5.

Although the present invention has been explained above with reference to Examples, the present Iridium E
It has been found that the C electrode can be applied to any electrochemical system involving oxygen, whether organic or inorganic.

The EC display body obtained by the present invention is used as a display for a clock calculator, a measuring instrument, etc., and a light control device for a shutter, etc. As described above, the present invention involves inserting a pair of reference electrodes into an electrolytic solution, immersing an iridium metal wire, and then applying a minimum potential of standard hydrogen electrode potential (RHE) to the pair of reference electrodes +0.
4) Below, a maximum potential of +1.0 to +1.7 V or more is applied alternately, the minimum potential and the maximum potential are continuously swept to form an iridium oxide metal wire, and the iridium oxide metal wire is used as an electrochromic electrode. Therefore, the oxygen in the electrolyte is sufficiently adsorbed to the iridium metal wire without being released as a gas, resulting in complete coloring, and iridium metal wire is preferable for electrochromic displays using this metal wire. It can exhibit transparent and colored electrode responses. Brief explanation of the drawings Figure 1...
Electrochemical cell structure, Figure 2...Electrochemical electronic measuring instrument and observation system, Figure 3...Potential sweep waveform, Figure 4...Iridium electrode Current response, 5th
Figure: Relationship between the number of sweeps and the length of the EC electrode (Vmi
n=50w1, V constant, Vmax parameter), 6th
Figure: Relationship between the number of sweeps and the growth of the EC electrode (■M
ax = 1.4■ constant, Vmilperameter).

Claims (1)

[Claims] 1. Insert a pair of reference electrodes into the electrolytic solution, immerse the iridium metal wire, and then apply a minimum potential of standard hydrogen electrode potential (RHE) of +0.4 V or less to the pair of reference electrodes, and a maximum potential of +1
．． An electrochromic electrode characterized in that an iridium oxide metal wire is formed by alternately applying 0 to +1.7 V or more and continuously sweeping the minimum potential and the maximum potential, and the iridium oxide metal wire is used as an electrochromic electrode. Method for manufacturing chromic electrodes.