KR20190136410A - Electrode for gas sensor and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a method of manufacturing an electrode for a gas sensor, which comprises the steps of: (a) pretreating a substrate; (b) printing electrode slurry on at least one region of the substrate pretreated in the step (a); and (c) drying and thermos-compressing the substrate on which the electrode slurry is printed in the step (b). In the step (b), the electrode slurry comprises carbon and a catalyst, wherein the catalyst includes at least one selected from a group consisting of silver, gold, platinum, palladium, ruthenium, rhodium, and combinations thereof. The electrode for a gas sensor manufactured by the manufacturing method is excellent in gas sensor detection characteristics.

Description

Electrode for gas sensor and its manufacturing method {ELECTRODE FOR GAS SENSOR AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an electrode for a gas sensor and a method of manufacturing the same.

The electrochemical gas sensor is composed of a working electrode, a counter electrode, and a reference electrode, and they detect a target gas by using a potential difference between the working electrode and the counter electrode between electrolytes. These electrodes are manufactured using deposition equipment or electroplating, but the deposition equipment is not only difficult to mix materials but also expensive, and electroplating has a problem in that the durability of the material is good but the mixing and plating solution is difficult.

Therefore, researches on a method of manufacturing an electrode are in progress to solve this problem.

One example of such a technique is disclosed in Patent Documents 1 and 2 below.

That is, the following Patent Document 1 relates to a sensor and a method of manufacturing the same, a non-conductive substrate portion, a non-conductive protrusion portion formed of a plurality of protrusions having elasticity and protruding above the substrate portion, and having electrical conductivity, wherein the plurality of protrusions and And an electrode part integrally covering an upper portion of the substrate portion on which the plurality of protrusions are formed so as to electrically connect the upper portion of the substrate portion exposed between the plurality of protrusions, wherein the height of the protrusions is greater than an interval between neighboring protrusions. The present invention discloses that the electric path from one side to the other side of the electrode portion is shortened by forming the elongated protrusion and contacting the neighboring protrusion when the force is applied in the horizontal direction to the substrate.

Patent Document 2 (1) using a patterned silk screen, the conductive silver ink to print a polyvinyl chloride (Polyvinyl chloride, PVC) film or polyethylene chlorinate (PET) film Step, (2) printing the counter electrode in a counter pattern using carbon black on the PVC film or PET film printed in the first step, (3) the counter electrode of the second step is printed Printing silver / silver chloride (Ag / AgCl) ink on a reference film as a reference electrode on a PVC film or a PET film, and printing the modified carbon nanotubes as a working electrode on a working pattern; 4) the step of enhancing the UV by printing the insulator in an insulating pattern on the PVC film or PET film printed with the modified carbon nanotubes of the three steps. Try.

However, Patent Documents 1 and 2 as described above use a screen printing method so that the composition and formulation of the material can be adjusted, so that the mixing is easy, but there is a difficult problem of improving the close adhesion between the substrate and the electrode slurry.

Republic of Korea Patent No. 10-1533974 Republic of Korea Patent Publication No. 2013-0119567

It is an object of the present invention to provide an electrode for a gas sensor with improved gas sensor sensing characteristics and a method of manufacturing the same.

The object of the invention is not limited to the above-mentioned object. The object of the present invention will become more apparent from the following description, and will be realized by the means described in the claims and combinations thereof.

According to an aspect of the present invention, there is provided a method of manufacturing an electrode for a gas sensor, the method comprising: (a) pretreating a substrate, (b) printing an electrode slurry on at least one region of the substrate pretreated in step (a); c) drying and thermocompressing the substrate on which the electrode slurry is printed in step (b), and in step (b) the electrode slurry comprises carbon and a catalyst, wherein the catalyst is silver, gold, platinum, At least one selected from the group consisting of palladium, ruthenium, rhodium, and combinations thereof.

In step (a), the substrate may be polytetrafluoroethylene or glass fiber.

In step (a), the pretreatment may be performed for 10 to 20 minutes at a temperature of 20 to 30 ° C. by a plasma cleaning method under an atmosphere of argon or nitrogen gas.

Printing in the step (b) may be carried out under the conditions of the temperature of 30 ~ 55 ℃ and humidity of 35 ~ 50%.

In step (b), the catalyst may be included in an amount of 5 to 30 wt% based on the total weight of the electrode slurry.

In the step (b), the electrode slurry may further include a binder and a solvent, and the binder may be included in an amount of 10 to 20 wt% based on the total weight of the electrode slurry.

The binder may be at least one selected from the group consisting of polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, polyethylene oxide, polyethylene glycol, and combinations thereof.

The solvent may be at least one selected from the group consisting of alpha terpineol, ethanol, metalol and combinations thereof.

Drying in the step (c) may be carried out for 2 to 5 hours at a temperature of 30 ~ 55 ℃ under the condition that the humidity is 35 ~ 50%.

Thermal compression in the step (c) may be carried out for 1 to 3 hours at a pressure of 50 ~ 150kg / cm ² under a temperature condition of 80 ~ 240 ℃.

After the step (c) may further comprise the step of (d) integrating the electrode body.

In the step (d), the second electrode body including the first surface on which the counter electrode and the reference electrode are formed and the first electrode body including the first surface on which the working electrode is formed are stacked on the second electrode body. Integrate at a pressure of 50 ~ 150kg / cm ² for 10-30 minutes under a temperature condition of ℃, the working electrode may be stacked to face the same direction as the counter electrode and the reference electrode.

An electrode for a gas sensor according to another embodiment of the present invention includes a second electrode body including a second substrate and a first electrode body including a first substrate stacked on the second electrode body. The electrode body and the second electrode body each comprise an electrode formed in at least one region of the first substrate and the second substrate, wherein the electrode is from the group consisting of silver, gold, platinum, palladium, ruthenium, rhodium and combinations thereof At least one selected.

According to an embodiment of the present invention, it is possible to provide an electrode for a gas sensor with improved gas sensor sensing characteristics and a method of manufacturing the same by adding various kinds of catalysts in an electrode slurry.

1 is a process chart for explaining a method for manufacturing an electrode for a gas sensor of the present invention.
Figure 2a is a photograph showing the working electrode formed on the first substrate of the present invention, Figure 2b is a photograph showing the counter electrode and the working electrode formed on the second substrate of the present invention.

The above objects, other objects, features and advantages of the present invention will be readily understood through the following preferred embodiments associated with the accompanying drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the invention to those skilled in the art.

EMBODIMENT OF THE INVENTION Hereinafter, the manufacturing method which manufactures the electrode for gas sensors of this invention is demonstrated in detail according to drawing.

1 is a process chart for explaining a method for manufacturing an electrode for a gas sensor of the present invention.

Referring to FIG. 1, first, a substrate is pretreated (S10).

In order to remove foreign substances from the substrate and improve the adhesion properties of the surface, the substrate is vacuumed at 2 × 10 ^-6 Torr or less using argon or nitrogen gas (gas ratio: 20) at a room temperature of 20 to 30 ° C., and the rotator is 5 RPM, The pressure may be plasma surface treatment for 10 to 20 minutes, preferably 15 minutes under conditions of 4 mTorr or less and RF power of 100 W or less. The free radicals are formed by the plasma surface treatment using the plasma cleaning method, and thus, the crosslinking effect between the substrate and the organic components between the electrode slurry, which will be described later, becomes easier, and thus the adhesive strength between the substrate and the electrode slurry is improved. Chemical gas sensors can maintain stability over the long term.

In this case, the substrate may include polytetrafluoroethylene (PTFE) or glass fiber, but is not limited thereto, and the substrate is not particularly limited as long as it is a material applicable to the substrate of the electrode.

Next, the electrode slurry is printed on the substrate (S20).

In order to prevent the printed pattern from spreading or damage to the substrate pre-treated in step S10, after the temperature is 30 to 55 ° C. and the humidity is naturally dried for 30 minutes or more under conditions of 35 to 55%, electrode slurry is applied to at least one region of the substrate. It can be printed to form an electrode. If the temperature is less than 30 ° C., the time taken to dry the substrate may be long, and if it exceeds 55 ° C., the function as an electrode substrate may be lost by shrinking of polytetrafluoroethylene (PTFE). If the humidity is outside the range of 35 to 55%, natural drying may be difficult, which is not preferable.

Here, the printing may deposit the electrode slurry on the substrate using a screen printer, and maintains a constant pressure and the moving speed to press the squeegee so that the thickness of the electrode and the distance between the electrodes can be kept constant. By using the screen fritter as described above, the process can be simplified, and anyone can easily perform the work.

The substrate may include a first substrate on which a working electrode is formed, and a second substrate on which a counter electrode and a reference electrode are formed, wherein the first substrate may be PTFE, and the second substrate may be glass fiber. In detail, a rectangular working electrode may be formed in one line on one screen plate, and the counter electrode and the reference electrode may be formed on the screen to face each other with interdigitate. The screen may be 200 to 400 mesh in size, and by simultaneously performing all processes under the same conditions, not only the physical properties of the electrode itself may be kept constant, but also the characteristics of the sensor may be maintained uniformly.

2A is a photograph showing a working electrode formed on a first substrate of the present invention, and FIG. 2B is a photograph showing a counter electrode and a reference electrode formed on a second substrate of the present invention.

2A and 2B, it can be seen that the working electrode, the counter electrode and the reference electrode are uniformly printed on the first substrate and the second substrate.

The electrode slurry may include carbon, a catalyst, a binder, and a solvent. Specifically, the electrode slurry may include 20 to 40 wt% of carbon, 5 to 30 wt% of a catalyst, 10 to 20 wt% of a binder, and 20 to 50 wt% of a solvent. After adding to the stirrer may be mixed for 6 hours to produce a viscosity of 6 ~ 60McP. If the agitation time is less than 6 hours, it is not preferable because the materials may not be sufficiently ground and mixed so that the bonding strength may drop.

If the carbon is less than 20% by weight, it is difficult to secure the conductivity, and when the carbon content is more than 40% by weight, the content of carbon relative to the binder is too high, and the electrode may be damaged by sintering during thermal compression.

The catalyst is added to improve the sensitivity, reaction time, recovery time, etc. of the gas sensor. If the catalyst is less than 5% by weight, it may be difficult to expect a significant improvement in functions such as the reaction time and recovery time of the gas sensor. If the percentage is exceeded, the manufacturing cost per sensor may increase due to an increase in manufacturing cost per electrode. In other words, the catalyst may be included in an amount of 10 to 80 parts by weight based on 100 parts by weight of carbon, and the catalyst may be at least one selected from the group consisting of silver, gold, platinum, palladium, ruthenium, rhodium, and combinations thereof. It can be platinum.

The binder is a material added to improve adhesion between the electrode slurry and the substrate during printing, and is selected from the group consisting of polymethylmethacrylate, polyvinylchloride, polyvinylbutyral, polyethylene oxide, polyethylene glycol, and combinations thereof. It may be at least one kind, the solvent may be at least one kind selected from the group consisting of alpha terpineol, ethanol, metalol and combinations thereof.

The content of each composition of the electrode slurry is very important because it is very closely related to the damage of the electrode during thermal compression, which will be described later, and to limit the content of the binder and the solvent to 10 to 20% by weight and 20 to 50% by weight, respectively. However, it may be adjustable depending on the content of carbon and catalyst.

Thereafter, the substrate on which the electrode is formed is dried and thermally compressed to form an electrode body (S30).

In step S20, the substrate on which the electrode is formed may be naturally dried for 2 to 5 hours at a temperature of 30 to 55 ° C. under a condition of 35 to 50% humidity. This means that if the temperature of natural drying is less than 30 ° C., the time taken to dry the substrate may be long, and if it exceeds 55 ° C., the first substrate, which is polytetrafluoroethylene (PTFE), shrinks and thus loses its function as an electrode substrate. Can be. If the humidity is outside the range of 35 to 55%, natural drying may be difficult, which is not preferable.

Then, thermal compression may be performed for 1 to 3 hours at a pressure of 50 to 150 kg / cm 2 under a temperature condition of 80 to 240 ° C. In more detail, since the shrinkage phenomenon occurs severely when the first substrate is heated, the first electrode body may be manufactured by performing thermal compression under a condition of a temperature of 80 to 150 ° C., and the second substrate may be less heat than the first substrate. Since it is strong, it can thermocompress on the conditions of 160-240 degreeC, and can manufacture a 2nd electrode body.

Finally, the electrode body is integrated (S40).

In step S30, the first and second electrode bodies, each of which has been dried and thermally compressed, are cut to the same size using a cutter, and then subjected to a pressure of 50 to 150 kg / cm2 for 10 to 30 minutes under a temperature condition of 80 to 150 ° C. Pressurization can be carried out. It is not only difficult to sinter the electrode when the temperature is lower than 80 ° C., but also may take a long time of thermal compression, and when the temperature is higher than 150 ° C., the substrate may contract and deform rapidly. If the pressure is less than 50 kg / cm 2, molding to a desired thickness can be difficult, and if it exceeds 150 kg / cm 2, excessively squeezing the electrode printed on the substrate can result in damage of the electrode and a change in resistance.

In more detail, a second electrode body including a first surface on which a counter electrode and a reference electrode are formed, and a first electrode body including a first surface on which a working electrode is formed on the second electrode body, are stacked. The first surface of the sieve and the first electrode body may be stacked in the same direction (lower direction) so that the respective electrodes may not be in contact with each other.

When the integration of the first electrode body and the second electrode body is completed as described above, one electrode S50 for close contact with the electrochemical gas sensor is obtained. The electrode for a gas sensor manufactured by the manufacturing method is excellent in gas sensor detection characteristics.

The present invention can provide an electrode for a gas sensor. The gas sensor electrode includes a second electrode body including a second substrate and a first electrode body including a first substrate stacked on the second electrode body, and the first electrode body and the second electrode body include: An electrode is formed on at least one region of the first substrate and the second substrate, respectively, and the electrode may be at least one selected from the group consisting of silver, gold, platinum, palladium, ruthenium, rhodium, and combinations thereof.

The present invention can provide a gas sensor. The gas sensor may include an electrode, a case accommodating the electrode, a case having an opening at an upper end thereof, and an electrolyte reacting with the electrode.

Example 1 Preparation of Electrode Body

Using polytetrafluoroethylene (PTFE) and woven glass fibers at room temperature, respectively, using argon or nitrogen gas (gas ratio: 20), the degree of vacuum is 2 × 10 ^-6 Torr or less, the rotator is 5 RPM, the pressure is 4 mTorr or less, RF The plasma surface treatment was performed under conditions of 100 W or less. Then, 30 wt% carbon, 21 wt% platinum, 15 wt% binder, and 34 wt% solvent were stirred and mixed for 6 hours to prepare an electrode slurry. Each electrode slurry was printed on PTFE and woven glass fibers at a temperature of 25 ° C. and a humidity of 46%. After 3 hours of natural drying at a temperature of 40 ° C. under 40% humidity, PTFE with electrode slurry printed thereon was subjected to thermocompression bonding at 120 ° C. at a pressure of 100 kg / cm 2 for 2 hours. The printed woven glass fiber was thermally compressed for 2 hours at a pressure of 100 kg / cm 2 at 200 ° C. to prepare first and second electrode bodies. The working electrode was formed in the first electrode body, and the counter / reference electrode was formed in the second electrode body.

Evaluation Example 1. Resistance Measurement

The resistance was measured as follows using the first and second electrode bodies prepared in Example 1.

Five regions of each of the working electrode and the counter / reference electrode were measured, respectively, and then the average was calculated. In addition, the same area of each of the working electrode and the counter / reference electrode was measured ten times, and then the average was calculated.

Table 1 is a result of measuring the resistance of the five areas of the working electrode and the counter / reference electrode, Table 2 is a result of measuring the resistance of the same area of the working electrode and the counter / reference electrode ten times.

Referring to Table 1 and Table 2, it was found that the stacking electrode had a relatively low resistance of about 15 mA and the counter / reference electrode of about 23 mA.

division Working electrode (Ω) Relative / Reference Electrode (Ω) medium 12.1 17.1 Prize 13.3 20.0 Ha 12.8 28.3 Left 12.6 18.5 Ooh 12.7 22.1 Average 12.7 21.2

Number of measurements Center of working electrode Center of Counter / Reference Electrode One 14.2 18.4 2 13.1 22.1 3 16.6 28.0 4 12.3 33.0 5 15.8 17.2 6 15.7 15.8 7 17.7 12.3 8 18.2 41.4 9 15.1 19.3 10 16.0 24.4 Average 15.4 23.1

As mentioned above, although the invention made by the present inventor was demonstrated concretely according to the said Example, this invention is not limited to the said Example and can be variously changed in the range which does not deviate from the summary.

Claims (13)

(a) pretreating the substrate;
(b) printing an electrode slurry on at least one region of the substrate pretreated in step (a); And
(c) drying and thermocompressing the substrate on which the electrode slurry is printed in step (b);
In the step (b), the electrode slurry includes carbon and a catalyst, wherein the catalyst is at least one selected from the group consisting of silver, gold, platinum, palladium, ruthenium, rhodium, and combinations thereof. .
The method of claim 1,
In (a), the substrate is a method of manufacturing an electrode for a gas sensor, which is polytetrafluoroethylene or glass fiber.
The method of claim 1,
The pre-treatment in the step (a) is a method of manufacturing an electrode for a gas sensor is carried out for 10 to 20 minutes at a temperature of 20 ~ 30 ℃ by a plasma cleaning method in the atmosphere of argon or nitrogen gas.
The method of claim 1,
Printing in the step (b) is a manufacturing method of the electrode for a gas sensor is carried out under the conditions of the temperature of 30 ~ 55 ℃ and humidity of 35 ~ 50%.
The method of claim 1,
The catalyst in the step (b) is a method for producing an electrode for a gas sensor is contained 5 to 30% by weight based on the total weight of the electrode slurry.
The method of claim 1,
In the step (b) the electrode slurry further comprises a binder and a solvent,
The binder is a manufacturing method of an electrode for a gas sensor is contained 10 to 20% by weight based on the total weight of the electrode slurry.
The method of claim 6,
The binder is at least one selected from the group consisting of polymethyl methacrylate, polyvinyl chloride, polyvinyl butyral, polyethylene oxide, polyethylene glycol, and combinations thereof.
The method of claim 6,
The solvent is a method for producing an electrode for a gas sensor is at least one selected from the group consisting of alpha terpineol, ethanol, metalol and combinations thereof.
The method of claim 1,
Drying in the step (c) is a method of manufacturing an electrode for a gas sensor is carried out for 2 to 5 hours at a temperature of 30 ~ 55 ℃ under conditions of 35 ~ 50% humidity.
The method of claim 1,
Thermal compression in the step (c) is a method of manufacturing an electrode for a gas sensor is carried out for 1 to 3 hours at a pressure of 50 ~ 150kg / cm ² under a temperature condition of 80 ~ 240 ℃.
The method of claim 1,
And (d) after the step (c), further comprising the step of integrating the electrode body.
The method of claim 11,
In the step (d), the second electrode body including the first surface on which the counter electrode and the reference electrode are formed and the first electrode body including the first surface on which the working electrode is formed are stacked on the second electrode body. Integrate for 10-30 minutes at a pressure of 50-150kg / cm ² under the temperature condition of ℃,
And the working electrode is stacked to face the same direction as the counter electrode and the reference electrode.
A second electrode body including a second substrate; And
A first electrode body including a first substrate stacked on the second electrode body,
The first electrode body and the second electrode body each include an electrode formed in at least one region of the first substrate and the second substrate, the electrode is silver, gold, platinum, palladium, ruthenium, rhodium and combinations thereof Gas sensor electrode containing at least one selected from the group consisting of.

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