JPS5827054A - Oxygen gas concentration cell - Google Patents

Abstract

PURPOSE:To attain a stable output characteristic and to permit a long service life by a construction wherein electrodes are formed on a raw sheet containing solid electrolyte ceramic powder, plural sheets are bonded to each other at the end portions under hig- temperature and high-pressure and sintered, and then the electrodes of thus obtained hollow cylinder type oxygen concentration cell and each shaped into a net-like form. CONSTITUTION:Plural electrodes 3, lead wires 2, 2', etc. are formed through screen printing on both front and rear sides of a raw sheet which contains solid electrolyte ceramic powder (such as ZrO2 stabilized with Y2O3), a thermoplastic organic bonding agent and an organic plasticizer. Thus obtained plural raw sheets are bonded to each other at the end portions under high-temperature and high-pressure to form a hollow cylinder type oxygen gas concentration cell element. At this time, as shown in the enlarged view, the electrodes 3 are each shaped into a net-like form. Then, the element is sintered under high-temperature. A width of the net-like electrodes (Pt or the like) is to be ca. 0.1-0.2mm.. By so doing, it becomes possible to prevent that output voltage becomes unstable and the electrodes 3 will be floated otherwise due to residence of O2 gas below and in the vicinity of the electrodes 3. Thus, a long service life and a stable output characteristic can be assured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oxygen gas concentration battery in which a plurality of cells are integrated in one element body using a solid electrolyte having oxygen ion conductivity.

Oxygen concentration cells using a solid electrolyte 'X' such as zirconia are widely used as oxygen concentration 11 for fuel cells, industrial measurement control, and automobile exhaust gas control.

The present inventors first found that the internal resistance was small and.

We have proposed a method for manufacturing an oxygen gas concentration battery that not only allows easy electrode formation and stable output, but also has a structure in which single cells are aggregated in a relatively simple process.

That is, the method includes the steps of forming electrodes by screen printing on a green sheet of a desired thickness containing a solid electrolyte powder, a thermal CIT plastic organic binder, and an organic plasticizer, and heating a plurality of the green sheets.

This process consists of a process of bonding under pressure to form a hollow cylinder, and a process of heating and sintering this hollow cylinder at a high temperature.

FIG. 1 is a perspective view showing an example of a #R elementary gas concentration cell body obtained by this method, in which 10 cells connected in series are integrated on the upper and lower surfaces of a hollow cylinder, etc. forming a battery.

In the figure, (1) is a hollow t&U cord, +21,
(2) is the lead, and (3) is the 11L love.

Considering the case where this oxygen gas concentration battery element is applied as an 02 sensor to detect 02 concentration 1 in exhaust gas for all automobiles, the inside of the hollow cylinder is the positive electrode based on air, and the outside exhaust gas side has a low 02 concentration. It becomes a negative pole, due to the difference in oxygen concentration.

Oxygen ions moving from the positive pole to the negative pole acquire electrons at the negative pole, and are emitted from the electrode and the vicinity of the pole as 02 gas to the outside of the elementary system. Therefore, if each outer electrode of the hollow simple body as shown in Fig. 1 is made to be airtight against the gas that is baked after applying platinum paste etc., the 02 gas under the electrode and in the vicinity Because the residence time of O2 becomes very long and the catalytic effect of platinum increases in the flammable gas atmosphere in the exhaust gas, a stable output voltage cannot be obtained with respect to the O2 concentration in the exhaust gas. Furthermore, the generated 02 gas tends to cause the electrode to gradually lift up and deteriorate the electrode strength.

For these reasons, conventionally well-known 02 sensors have not been provided with multi-hole platinum 1L poles using various methods. It required a forming technique and the process was complicated.

The present invention is intended to eliminate the above drawbacks.

In forming the electrodes of the oxygen gas concentration cell element fabricated using the raw sheet method described above, by forming a mesh electrode using the screen printing method, it was possible to obtain output signals and characteristics with good reproducibility. This made it possible to provide highly reliable oxygen gas concentration batteries.

Hereinafter, the present invention will be explained according to examples.

Example Y 20 s (t o wt%) of Z r O2 powder (average particle size 0.7 μm) and a well-known organic thermoplastic binder and an organic plasticizer to obtain a ceramic green sheet A green sheet with a diameter of 0.5 vm was obtained. After punching this into a desired shape (approximately 15 cm x 100 cm), platinum is printed on the top and bottom surfaces of the raw sheet using a screen having a mesh pattern and lead portion prepared in advance as shown in the plan view of Figure 2. Printed ink. The printing ink was made to an appropriate viscosity with a thinner made from platinum powder and a thermoplastic organic binder and an organic plasticizer having the same composition as those used for the raw sheet. After connecting the raw sheets in series between the 'vL poles using the platinum printing ink, a single raw sheet with a punched center part is sandwiched between the raw sheets to facilitate the formation of a hollow tube. After heating the ends of the stiff pieces and bonding them under pressure, the temperature is 1650
Sintering was carried out at 1:' for 5 hours. Finally, unnecessary parts are removed by machining, and the appearance is the same as the perspective view in Figure 1, so illustration is omitted.
) was obtained.

Comparing the output characteristics of the oxygen gas concentration battery element having a mesh electrode obtained by the above method and the conventionally known 02 sensor element against the A/F of exhaust gas, it is found that the former has a considerably lower A/F. A/' over a wide range
It changes almost linearly with respect to PK, indicating that the oxygen concentration in exhaust gas can be directly detected.

According to the present invention, in which a mesh electrode (3) is formed on a thin raw sheet and cells are integrated in a hollow simple body to form an oxygen gas concentration battery element, the dimensions of the electrode can be determined by screen printing. Since the accuracy and reproducibility of printing accuracy can be significantly improved, it is possible to provide an oxygen gas concentration battery element having stable output characteristics for the A/F. In addition.

The size of the mesh and [7] depends on the outer circumferential size of the electrode surface,
The width of the platinum part is 0.1. As a result of studies conducted by the present inventors, it has been found that it is preferable to set the thickness to about 0.2 mm to 0.2 mm. If it is too narrow, the internal impedance of the element will increase, and if it is too wide, the above-mentioned variations in output characteristics due to gas retention and deterioration of the life of the electrodes will become a problem. The ability to narrow the mesh width in this manner is due to the thin wall thickness of the monolithic body of the present invention.

As explained above, the present invention makes it possible to provide an oxygen gas concentration cell body that exhibits stable output characteristics with respect to stale oxygen concentration and has a long life, and has great industrial value.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an oxygen gas concentration battery prepared by the green sheet method, Fig. 2 is a plan view for explaining the electrodes of the oxygen gas concentration battery of the present invention, and Fig. 3 is a perspective view of an oxygen gas concentration battery prepared by the raw sheet method. A characteristic diagram comparing the output characteristics with respect to h/F of the Isodan battery and the conventional oxygen gas sensor element. In the figure, (1) is a hollow simple body, and (2) is a lead. (3) is an electrode. Agent Makoto Kuzuno - FPA of drawings (no change in content) Figure 1 Procedural amendment (method) Opened 7 years 2 Door 911 Commissioner of the Japan Patent Office 1, matter ↑. Display patent application Sho 56-126827
No. 2, Title of the invention: Oxygen gas pale flame battery 3, Representative Hitoshi Katayama of the person making the amendment Part 6: A close look at the subject of the amendment, specification and drawings. 7. A look at the content of the amendment, a look at the details, and a look at the drawings (no changes to the content). that's all

Claims (1)

[Claims] A step of creating a green sheet containing a solid electrolyte ceramic powder, a thermoplastic organic binder, and an organic plasticizer to a desired thickness, and a step of forming electrodes on the green sheet by screen printing. , Mutual heating of the ends of the plurality of green sheets forming the electrodes. In the oxygen gas concentration battery, which comprises the steps of creating a hollow cylinder by bonding under pressure, and heating the hollow cylinder at a high temperature and sintering it, the above! An oxygen gas concentration battery characterized by having electrodes formed in a mesh shape.