JPS6072172A - Manufacture of electrolyte tile for fuel cell - Google Patents

Abstract

PURPOSE:To obtain porous ceramics having high strength, high porosity, and labyrinthine fine pores by burning a sheet obtained by adding wood pulp as fibrous material to gamma-lithium aluminate powder. CONSTITUTION:gamma-lithium aluminate crushed to powder having a particle size of 20mu or less is used as sintering inorganic material. Wood pulp is selected from among various organic fibrous materials to increase function of reinforcing material and porosity. The adding amount of wood pulp is limited to 3-15wt% to the total weight of dried sheet which is not sintered yet. For burning, temperature is increased at a rate of 50-200 deg.C/h from room temperature to 1,000- 1,400 deg.C during which wood pulp is burned and vaporized, and labyrinthine fine pores are formed, then lithium aluminate is sintered. Sintering is continued at 1,000-1,400 deg.C for 1-3hr. Eutectic electrolyte is impregnated to gamma-lithium aluminate porous sheet at 500-650 deg.C to obtain an electrolyte tile for fuel cell.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing electrolyte tiles for fuel cells.

Conventional porous ceramic materials for electrolyte tiles for fuel cells include unglazed pottery, foamed glass ceramics, and ceramic foam, although each type has different pore properties. However, these ceramics lack the hardness and fineness required of ceramics for use as electrolyte tiles for fuel cells. Furthermore, when the pores are filled with various inorganic substances or electrolytes, some may lack ion permeability and electron conductivity. In addition, even if ion permeability and electron conductivity are satisfied, various inorganic substances and electrolytes filled in the pores may be washed away through the pores, or the N rating of ceramics alone may not have sufficient strength. Many had.

Furthermore, when making ceramic sheets, there are methods such as injection molding, extrusion molding, and isostatic pressing that do not use papermaking methods. However, when using the method of Kori, et al., when a ceramic sheet with a large area of 50 cm square or more is made, the surface will crack or loosen and will not be uniform.

Conventionally, in the method of making a porous sintered body, a sheet-like material obtained by adding 51 to 70% by weight of wood pulp as a fibrous material to α-alumina as a powder of a sinterable substance is fired. There is a method to obtain a thin and dense porous body. However, in this method, in order to obtain a high porosity, the content of wood pulp is high (and since α-alumina is used, it is necessary to 160
It was necessary to fire at a high temperature of 00G.

In the present invention, we have developed a ceramic material that is dense, strong, and has a high porosity (like a labyrinth of pores) that is sufficient to eliminate or overcome the above-mentioned drawbacks. As a method for producing a porous body, τ-lithium aluminate with a particle size of 20μ or less is used as the sinterable inorganic material, and the amount of wood pulp added is as small as 6 to 15% by weight. This is a method for producing electrolyte tiles for fuel cells that can be sintered at a lower temperature than the method using the sintered material, and has a porosity of 40 to 80% of the total volume of the sintered product.

As an electrolyte tile for fuel cells, alumina is dense and has excellent electrical insulation properties. However, alumina reacts with lithium carbonate used as an electrolyte and turns into lithium aluminate. Therefore, in the present invention, rI, which has the most stable structure among lithium aluminates,
J thium aluminate is produced and used as the sinterable inorganic material.

To explain in more detail below, as a sinterable inorganic substance,
The r-lithium aluminate is crushed to a particle size of 20μ or less, and wood pulp is selected from various organic fibers and wood pulp is added in order to function as a reinforcing material and increase the porosity. The amount is limited to 3 to 15% by weight based on the total weight of the sheet when dry before sintering.

The method for producing the sintered material begins with a solid content of 3 to 15% by weight of fibrous material and a powder of sinterable inorganic material.
Approximately 60 times the weight of water is added and wet-mixed to prepare an aqueous slurry suitable for papermaking, a flocculant is added to cause agglomeration, papermaking is performed using a papermaking machine, and the slurry is formed into a sheet or a plate. This molded product is placed in a firing furnace and fired in an oxidizing atmosphere. Firing is carried out at a rate of 5 degrees per hour from room temperature to 1,000-1,400 degrees Celsius, where the wood pulp burns out, vaporizes, creates a labyrinth-like pore, and then sinters the lithium aluminate.
Sintering is carried out by increasing the temperature at a rate of 0 to 20°C. As described above, by using r-lithium aluminate, it is possible to create a dense structure with a large porosity and a maze of pores at a lower temperature and with the addition of about 3 to 15% of wood bulbs. It becomes possible to manufacture high quality and strong electrolyte tiles for fuel cells.

Specific examples of the present invention will be described below. Note that all compositions are N = ratio.

<Example 1> (5) Sample preparation (I3) In a container containing about 207 to 21 parts of flocculant, 1 part of water and 5 parts of water pulp.
of water, stir for 20 minutes to fully disperse it in water, and add 1. - Add 30 parts of IJ thium alumina) to 1
Stir thoroughly to make an aqueous slurry. Add 3Q parts of sulfuric acid band (15% aqueous solution) prepared in advance into the solution, stir for 2 minutes, and check that the pH has become 4 or less.
Confirmed with test paper, this was also a pre-made polyacrylamide polymer flocculant (Sunpoly N-5oo 0.
Add 20 parts of 2% water bath solution) and stir for 1 minute to coagulate.

The sample agglomerated in the above manner is made into a paper using a paper making machine.
It forms a sheet with an angle of o to 60σ and a thickness of 1 to 5 nrrn.

After drying this, put it in an electric furnace and put it in an oxidizing atmosphere.
From room temperature to 100°C/100°C, with air flowing if necessary.
Heating at a speed of I-I, the wood pulp is burnt and vaporized to form a labyrinth of pores, and then the temperature is raised to 1,300°C, at which point the lithium aluminate sinters, and heated in an electric furnace. When the temperature reached 1.300° C., it was maintained at this temperature for 2 hours to sinter the r-lithium aluminate, producing a fuel cell electrolyte tile with a porosity of 58%.

<Example 2> (5) Preparation of sample (13) Using a flocculant with the above composition (5) O13), sheet-shaped fuel cell electrolyte tiles were prepared in the same manner as in Example 1. Obtained.

The ceramic porous body thus obtained has excellent performance as an electrolyte tile used in fuel cells and is also excellent in durability.

According to the present invention, a ceramic porous body that is thin, dense, and has a high porosity (with continuous pores like a labyrinth) is produced.

The present invention incorporates the advantages of both the conventional method of producing a thin, pore-free, dense metal oxide and the method of producing a foamable porous material, and the porosity can also be adjusted by adding wood pulp. It can be changed freely depending on the quantity. In addition, the complicated processing step after foaming with polyurethane, which is a problem in the production of ceramic foam, is eliminated, so the production process is simplified. In addition, by using r-lithium alumina-1-ip and with a small amount of wood pulp,
Since the porous ceramic body 9j, which is dense and strong, is formed at a lower temperature, an energy saving effect is produced. Furthermore, it can be used in places where thermal expansion and contraction occur repeatedly, places where stress is applied, and in particular places where thermal stress, electrical stress, and mechanical stress are applied repeatedly, such as electrolyte plates for electrolyte batteries. Furthermore, since paper-making technology is used to form sheet-like materials for firing, it is possible to continuously manufacture sheet-like materials of uniform thickness, and the thickness can also vary. It is possible to implement within a reasonable range.

Patent Applicant Toppan Printing Co., Ltd. Procedural Amendment (Mutsu) 1. Indication of the case Patent Application No. 181485 of 1981 2. Name of the invention Method for manufacturing electrolyte tiles for fuel cells 3. Person making the amendment Relationship with the case Patent Applicant Address 1-5-1-4 Taito, Taito-ku, Tokyo Subject of Amendment Description 1 Name of the Invention Method for manufacturing electrolyte tiles for fuel cells 2 Scope of Claims (1) Particle size 2oμ or less By mixing the γ-lithium aluminate powder and wood pulp in water to form an aqueous nulla 1) suitable for papermaking, adding a flocculant to adsorb and agglomerate the powder to the pulp, and then producing paper.

Obtain a sheet-like or plate-like molded product containing 3 to 15 wood pulp based on the total dry weight before firing, and fire the molded product in an oxidizing atmosphere to burn off and vaporize the wood pulp,
After that, γ-lithium aluminum battery type 1 was prepared.
9. Method of manufacturing quality tiles.

3. Detailed explanation of Ming Seki 1" is a bastard.

As for the ceramic porous material used as a conventional electrolyte tile holder for fuel cells, the properties of each pore are different.
There are unglazed pottery and foam glass Ceraminku 7 and Ceraminox Humame. However, these ceramics lack the hardness and fineness required for ceramics used as electrolyte tile nursery materials for fuel cells. It is also used by filling the pores with various inorganic substances and electrolytes.
There are quite a few materials that lack ion permeability and electronic conductivity. In addition, even if ion permeability and electron conductivity (1+) are satisfied, various inorganic substances and electrolytes filled in the pores may be washed away from the pores, or the ceramic skeleton alone may not be strong enough to produce a high temperature Many of them had the following drawbacks.

Furthermore, when making ceramic sheets, there are methods such as injection molding, extrusion molding, and isostatic pressing that do not use papermaking methods. If a ceramic sheet with a large area as described above is made, the surface will be cracked or cracked and the surface will not be uniform.

Conventionally, in the method of making a porous sintered body, a sheet-like material obtained by adding 51 to 70% by weight of wood pulp as a fibrous material to α-alumina as a powder of a sinterable substance is fired. However, in order to obtain a high porosity, this method requires a high content of wood pulp and also uses α-alumina. 1,500 to 1 to obtain a sintered material
, it was necessary to bake at a high temperature of 60°C.

The present invention provides ceramics that are dense, strong, have high porosity, and have a labyrinth of pores that are sufficient to eliminate or compensate for the above-mentioned drawbacks. As a method for producing a porous body, γ-lithium aluminate with a particle size of 20 μm or less is used as the sinterable inorganic material, and the amount of wood pulp added is as small as 3 to 15% by weight. Electrolyte for fuel cells, which enables sintering at a lower temperature than the method using alumina, and impregnates electrolyte components into a porous material with a porosity of 40 to 80% of the total volume of the sintered material. This is a method for manufacturing tiles.

As a nursery material for electrolyte tiles for molten carbonate fuel cells,
Alumina is dense and has electrical insulation properties of 1=Iij. However, alumina reacts with lithium carbonate used as an electrolyte in the fuel cell 4 and turns into an aluminate. Therefore, in the present invention, the most stable lithium alumina 1. [Produce γ-lithium alumina 1 with the structure and use it as a sinterable inorganic material.

To explain in more detail below, as a sinterable inorganic substance,
γ-lithium aluminate is crushed and used as grains (sheep) of less than 20μ, and wood pulp is selected from various organic fibers for the purpose of functioning as a reinforcing material and increasing the porosity.
The amount of wood pulp added is 6 to 15% by weight relative to the total weight of the sheet when dry before sintering.

The method for producing sintered '4'a quality is to first add water in an amount of 5 to 30 times the weight of the solid content, which also includes powder of 3 to 15 weight percent fibers and sinterable inorganic substances. Te f! ]+I mixing, adjusting to an aqueous slurry suitable for paper making, adding coagulant Z5 to coagulate, making paper using a paper making machine, and forming into a sheet or plate. This molded product is placed in a firing furnace and fired in an oxidizing atmosphere. Firing involves burning and vaporizing the wood pulp at room temperature.
Create a maze-like pore with pores, then sinter the lithium aluminate from 1,000 to 1,400℃, 1
Sintering is carried out by increasing the temperature at a rate of 50-200''C per hour.1-3 at 1,000-1,400°C.
Perform time baking. As described above, by using r-lithium aluminate, it is possible to achieve a dense structure with a large porosity and a maze of pores at a lower temperature and with the addition of about 6 to 15% of wood pulp. It becomes possible to manufacture a holding material for electrolyte tiles for fuel cells that has high quality and high strength.

An electrolyte tile for a fuel cell can be obtained by impregnating the γ-lithium aluminate porous body obtained in the above step with a eutectic composition electrolyte component at a temperature range of 500° to 650°C.

Specific examples of the present invention will be described below. In addition.

All compositions are by weight.

<Example 1> (A) Preparation of sample (B) In a container containing about 21 parts of flocculant, 1 part of water and 5 parts of wood pulp
1.30 parts of γ-lithium alumina was added thereto and stirred for 1 minute to form an aqueous slurry. Add 30 parts of sulfuric acid band (15% aqueous solution) prepared in advance into the solution, stir for 2 minutes, and check that -P becomes 4 or less.
Confirm with test paper, add 20 parts of a polyacrylamide polymer flocculant (02% aqueous solution of Sunpoly N-500) prepared in advance, and stir for 1 minute to flocculate.

The sample agglomerated in the above manner is made into a paper using a paper making machine.
It is made into a sheet with 0 to 30 CT+l square and 1 to 5 wrl thickness. After drying, put it in an electric furnace and heat it in an oxidizing atmosphere, with air flowing if necessary, from room temperature to 100'.
Heating at a rate of C/H, the wood pulp is burnt and vaporized,
The pores form a maze of pores, and then the lithium aluminate sinters.The temperature is increased to 1.300°C, and when the temperature of the electric furnace reaches 1.300°C, it is held at this temperature for 2 hours. Then, γ-lithium aluminate was sintered to produce a porous body having a porosity of 58% and used as an electrolyte holding material for a fuel cell. The bending strength of this porous body is 55 2/d
There was. Eutectic composition electrolyte melt for γ-lithium aluminate porous (475% by weight lithium carbonate 7 μm 52
．． Impregnation with 5 g of potassium carbonate was carried out in an electric furnace in an oxidizing atmosphere at a heating rate of 60°C/H to reach 550°C and held at 550"C for 1 hour. The ratio of the electrolyte material to the electrolyte is 45:55 (weight ratio), and its bending strength is 1.1.
o o 1'-y/'cit, which is equivalent to or greater than the conventionally known value.

A molten carbonate fuel cell was constructed using the electrolyte tile of this example, and a single cell test was conducted under the following conditions.

Electrode: Porous nickel plate Test temperature = 65oC Cathode gas: A1r + 3o CO2 Manode gas: H2-1-20% CO2 Under the above test conditions, when the current density is 150+n1 to /7, the voltage is 075■, which is equivalent to the conventional example or higher, demonstrating the effectiveness of the fuel cell electrolyte tile of the present invention. In addition, no defects were observed in the electrolyte tile in this single cell test or a separate heat cycle test, confirming that the electrolyte tile of the present invention is excellent in terms of durability and life characteristics.

<Example 2> A. Sample preparation "γ-lithium aluminate (average particle size 1oμI11)
B. Flocculant A sheet-shaped fuel cell electrolyte tile was obtained in exactly the same manner as in Example 1 using the compositions (A) and (B) as described above.

The battery output performance of this was similar to that of Example 1.

As mentioned above, the process of making a γ-lithium aluminate porous body involves two methods: the conventional method of making a thin, pore-free, dense metal oxide, and the method of making a fugitive porous body. It incorporates the advantages of

The porosity can also be arbitrarily controlled by adjusting the amount of wood pulp added. 1- Since the complicated processing step after foaming with polyurethane, which is a problem in the production of ceramic foam, is eliminated, the production process of the porous body is simplified. Also, at lower temperatures.

Since a dense and strong γ-lithium aluminate poly'TL body is obtained, an energy saving effect is produced.

Furthermore, the pores of the γ-lithium aluminate porous material obtained by the method of the present invention are labyrinth-like, so it is resistant to thermal stress (and has excellent electrolyte impregnation and retention ability).

The mechanical strength of the electrolyte tile also improved (
Ru.

Therefore, by using the electrolyte tile manufactured by the method of the present invention, that is, by papermaking θ, it was possible to construct a molten carbonate fuel cell with excellent cell performance and economical efficiency.

According to the present invention, it is easy to increase the size of electrolyte tiles for fuel cells, so it greatly contributes to promoting the development of high-temperature fuel cells.

patent applicant Toppan Printing Co., Ltd. Representative Kazuo Suzuki

Claims (1)

[Claims] (1) γ-lithium aluminate powder with a particle size of 20μ or less and wood pulp are mixed in water to form an aqueous slurry suitable for papermaking, and a coagulant is added to adsorb and coagulate the powdered pulp to make paper. By this, a sheet-like or plate-like molded product containing 3 to 15% of wood pulp based on the total dry weight before firing is obtained, and the molded product is fired in an oxidizing atmosphere to burn off and vaporize the wood pulp. , and then sintering the powder of r-lithium aluminate.