JPH04262251A - Manufacture of electrochemical element - Google Patents

Abstract

PURPOSE:To manufacture an electrochemical element having high time stability by preventing the occurrence of peeling between a macromolecular film and a solid electrolyte layer on the electrochemical element provided with a plurality of electrodes including a working electrode formed on an insulating substrate, a water repellant macromolecular film formed on the electrodes, and the solid electrolyte layer formed on the macromolecular film. CONSTITUTION:An electrode plate 6 is provided with a plurality of electrodes 3 and 4 including a working electrode 2 which are formed out an insulating substrate 1 and a water-repellant macromolecular film 5 covering the electrodes 2, 3 and 4. The macromolecular film 5 of the electrode plate 6 undergoes plasma treatment which is effective for the reinforcement of chemical bonding power, etching effect and anchor effect. Thereafter, the macromolecular film 5 is covered with a solid electrolyte layer 7.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a method for manufacturing an electrochemical element used for detecting a specific gas component by utilizing a redox reaction, and specifically relates to a method for manufacturing an electrochemical element that is used to detect a specific gas component by utilizing an oxidation-reduction reaction. The present invention relates to a method for manufacturing an electrochemical element including electrodes and a solid electrolyte membrane covering an insulating substrate between the electrodes.

0002

[Prior art] Using redox reactions electrochemically,
Many electrochemical gas sensors that detect gases in the atmosphere, such as carbon monoxide, hydrogen, alcohol, nitrogen oxides, sulfur oxides, etc., have been proposed so far. Generally, this type of gas sensor has high sensitivity and is therefore used in the field of industrial gas concentration detectors.

[0003] This type of electrochemical device is disclosed in Japanese Unexamined Patent Publication No. 1-15
As disclosed in Japanese Patent No. 6657, three types of electrodes, a working electrode, a counter electrode, and a reference electrode that serves as a reference potential for the working electrode, are formed side by side on an insulating substrate, and these electrodes and the electrode The insulating substrate in between is covered with a solid electrolyte membrane made of a polymer such as sulfonated perfluorocarbon, and is also called a planar sensor.It is extremely small, precise, and has high quality by using thin film formation technology and microfabrication technology. It is expected to be a sensor with excellent performance.

By the way, it is difficult to determine the activity required for the electrodes of an electrochemical device in which a working electrode, a counter electrode, and a reference electrode are provided on an insulating substrate, and a solid electrolyte membrane is provided to cover these electrodes and the insulating substrate between the electrodes. In order to stabilize the electrolyte, it is effective to interpose a water-repellent polymer membrane between the electrode and the solid electrolyte membrane. However, since this solid electrolyte membrane functions as a proton conductor only when water is retained, the adhesion between the solid electrolyte membrane and the water-repellent polymer membrane is weak, and furthermore, changes in temperature and humidity can cause the solid electrolyte to deteriorate. When the membrane swells or expands and contracts, separation occurs between the solid electrolyte membrane and the polymer membrane, resulting in loss of function as an electrochemical element.

[0005]

Problems to be Solved by the Invention Therefore, the problems to be solved by the present invention are to provide a plurality of electrodes including a working electrode formed on an insulating substrate, a water-repellent polymer film formed on the electrodes, and a water-repellent polymer film formed on the electrodes. Provides a method for manufacturing an electrochemical device that prevents peeling between a polymer membrane and a solid electrolyte membrane of an electrochemical device that has a solid electrolyte membrane formed on a molecular membrane and improves stability over time. It is something to do.

[0006]

[Means for Solving the Problems] A method for manufacturing an electrochemical device according to the present invention includes an electrode comprising a plurality of electrodes including a working electrode formed on an insulating substrate and a water-repellent polymer film covering these electrodes. The method is characterized in that after the polymer membrane of the plate is subjected to plasma treatment, the polymer membrane is coated with a solid electrolyte layer.

The present invention will be explained below with reference to the drawings. FIG. 1 is a sectional view showing the structure of an electrochemical gas sensor according to an embodiment of the electrochemical element of the present invention.

In FIG. 1, an insulating substrate 1 has a working electrode 2.
A reference electrode 4 is formed that serves as a reference potential for the counter electrode 3 and the working electrode 2. These electrodes 2, 3, and 4 are covered with a water-repellent polymer film 5 to constitute an electrode plate 6. After the polymer film 5 of the electrode plate 6 is subjected to plasma treatment, a solid electrolyte layer 7 having proton conductivity is formed thereon, thereby completing the intended electrochemical device 8.

Here, as the insulating substrate 1, for example, a silicon substrate, an alumina substrate, various other ceramic substrates, and other organic substrates such as epoxy resin are used. The working electrode 2, the counter electrode 3, and the reference electrode 4 are formed of various electrode materials such as platinum and gold on the insulating substrate 1 by vacuum evaporation, sputtering, or the like. The polymer film 5 is made of water-repellent material such as fluororesin such as polytetrafluoroethylene or hydrocarbon polymer such as polyethylene and polypropylene by casting, dipping, vapor deposition, sputtering, etc. on these electrodes 2, 3, and 4. It is composed of polymers.

Further, this polymer film 5 is subjected to plasma treatment. The atmospheric gas for this plasma treatment is, for example, Ar,
O2, CO, N2, etc. are suitable. When this plasma treatment is applied to the polymer membrane 5, the adhesion with the solid electrolyte layer 7 is improved due to strengthening of chemical bond strength, etching effect, anchor effect, etc., and the effect of preventing the solid electrolyte layer 7 from peeling is obtained. It will be done.

The solid electrolyte layer 7 is composed of a polymer electrolyte material having proton conductivity such as polystyrene sulfonate polymer or perfluorosulfonate polymer, or an antimonic acid compound. Perfluorosulfonate polymer (trademark: Nafion, manufactured by DuPont) is most suitable because of its excellent properties.

0012

[Function] Electrochemistry comprising multiple electrodes including a working electrode formed on an insulating substrate, a water-repellent polymer film formed on this electrode, and a solid electrolyte film formed on this polymer film. Plasma treatment of the polymer film of the device imparts to the polymer film chemical bonding strength, etching effect, anchor effect, etc. that are effective in preventing peeling of the solid electrolyte membrane.

[0013]

[Example 1]

[Comparative Example 1] Insulating substrate 1 made of oxidized silicon
A platinum working electrode 2 and a counter electrode 3 were formed thereon by sputtering, and a reference electrode 4 was formed by vacuum evaporation. By casting a polyperfluorofuran solution on these electrodes 2, 3, and 4, a film thickness of 0. A polymer film 5 having a thickness of 0.01 μm was formed. The polymer film 5 of the electrode plate 6 thus obtained was subjected to plasma treatment under the following conditions. First, the electrode plate 6 is placed in a plasma processing apparatus whose pressure is reduced to 0.003 Torr, and Ar gas is applied at a pressure of 0.003 Torr. It was introduced until the pressure reached 1 Torr. And 13. Plasma treatment was performed by applying a high frequency of 56 MHz and 30 W for 10 minutes. Next, Ar
Turn off the gas and return to 0. After reducing the pressure to 0.003 Torr, the pressure was returned to normal pressure. A perfluorosulfonate polymer (
A solid electrolyte layer 7 having a film thickness of 3 μm was formed by casting with an n-2 propanol solution of proton-substituted Nafion (trademark manufactured by DuPont) and drying to form a solid electrolyte layer 7 with a film thickness of 3 μm, thereby obtaining an electrochemical CO gas sensor according to an embodiment of the present invention. .

On the other hand, an electrochemical CO gas sensor according to a comparative example was manufactured using the same materials and under the same conditions except for plasma treatment.

[0015] In order to evaluate the adhesion and gas detection characteristics of these two types of CO gas sensors, the following heat cycle test was conducted. (1) 20℃, 60%R. 24 hours (2
) 50°C, 20%R. 24 hours in H atmosphere (3) 2
0°C, 60%R. 24 hours (4)-20 in H atmosphere
°C, 100% R.C. One cycle consisted of leaving the sample in an H atmosphere for 24 hours, and this cycle was repeated five times.

As a result, in the CO gas sensor of the comparative example that was not subjected to plasma treatment, it was visually confirmed that the solid electrolyte layer 7 had peeled off, whereas the polymer film 5 and the solid electrolyte layer of the CO gas sensor of the example were visually confirmed to have peeled off. No change was observed between the electrolyte layers 7 even when observed using an optical microscope or SEM.

[0017] Regarding the change over time in the gas detection characteristics at 1000 ppm of CO gas, the CO gas sensor of the comparative example that was not subjected to plasma treatment showed a drastic decrease phenomenon already within the above five cycles. In the CO gas sensor of the example, even a phenomenon of deterioration was not observed.

[0018]

Example 2 The electrode plate 6 obtained in Example 1 was subjected to plasma treatment under the following conditions. First, the electrode plate 6 was set at 0. 003To
Place it in a plasma polymerization apparatus reduced to rr, and add 1.0% tetrafluoroethylene gas. 5ml/min, pressure 0.
It was introduced so that the pressure was 1 Torr. And 13. 5
6MHz, 5W high frequency was applied for 1 minute. 01μ
A polymer film 5 of m was formed. Subsequently, the surface of this polymer membrane 5 was coated with 0. 13. In an O2 atmosphere of 1 Torr. 56
Plasma treatment was performed by applying a high frequency of MHz and 30 W for 10 minutes. Next, stop the Ar gas and return to 0. 0
After reducing the pressure to 0.03 Torr, the pressure was returned to normal pressure. Example 1 was applied on the polymer film 5 of the electrode plate 6 after plasma treatment.
After casting with an n-2 propanol solution of proton-substituted perfluorosulfonate polymer (trademark: Nafion, manufactured by DuPont) under the same conditions as described above, the solid electrolyte layer 7 with a thickness of 3 μm was formed by drying, and the solid electrolyte layer 7 with a thickness of 3 μm was formed. The electrochemical type CO gas sensor according to the example was used.

When this gas sensor was tested under the same conditions as in Example 1, no peeling of the solid electrolyte layer 7 was observed, and no deterioration in the gas detection characteristics over time was observed.

[0020]

According to the method for producing an electrochemical device according to the present invention, it is possible to prevent the occurrence of peeling between the polymer membrane and the solid electrolyte layer, and to obtain an electrochemical device with high stability over time.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an electrochemical device according to an embodiment of the present invention.

[Explanation of symbols]

1 Insulating substrate 2 Working electrode 3. Opposite 4 Reference pole 5 Polymer membrane 6　Electrode plate 7 Solid electrolyte layer 8 Electrochemical element

Claims (1)

[Claims] 1. After plasma-treating the polymer film of an electrode plate comprising a plurality of electrodes including a working electrode formed on an insulating substrate and a water-repellent polymer film covering these electrodes, the polymer film is A method for producing an electrochemical device characterized by coating a membrane with a solid electrolyte layer.