JPS6081772A - Manufacturing method of electrolytic tile for fuel cell - Google Patents

Abstract

PURPOSE:To produce a porous structure of ceramics with high density and strength and with high porosity and a labyrinthine pattern of pores by using r-lithium aluminate of a specific grain diameter as a sintered inorganic substance and by specifying the addition of wood pulp to within a certain limit. CONSTITUTION:As an inorganic material is used r-lithium aluminate which is produced by the following process: lithium hydroxide and/or lithium chloride and gamma-Al2O3 are calcined at 1,000 deg.C for more than 1hr and cooled down, and this calcined product is then ground into pieces with a ball mill until the average diameter of grains will be less than 1mu. As a fiber material is added a certain amount of wood pulp which is by weight 3-15% of the total dry weight of uncalcined sheet-like material. And this mixed water base slurry is adjusted to be 7 in pH with an inorganic acid or alkali water solution, and then condensed and prepared to a sheet by adding a coagulating agent and a surface active agent. As for calcination, the temperature is raised from room temperature by 30-80 deg.C/H and kept at 500-700 deg.C for 1-3hr, and then raised again by 100- 300 deg.C/H and held at 1,000-1,300 deg.C for 1-3hr.

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 lack the hardness and fineness required of ceramics for use as electrolyte tiles for fuel cells. In addition, when the pores are filled with various inorganic substances or electrolytes, there are quite a few that lack ion permeability and electron conductivity. It's a size.
Even if the ion permeability and electron conductivity are satisfied, there are drawbacks such as the various inorganic substances and electrolytes filled in the pores being washed away from the pores, or the drawback that ceramics alone do not have sufficient strength. I had a lot of things.

Furthermore, when making ceramic sorts, there are methods such as injection molding, extrusion [molding], isostatic pressing, etc. that do not use the paper-making force method. However, these methods
When ceramics/tablets with a large area of 30 square meters or more are made, the surface becomes cracked or distorted and becomes uneven.

Traditionally, in the method of making electrolytic tiles for direct fuel use, 51 to 70% of alumina was added as a sinterable substance powder, and 51 to 70% of wood valve was added as a fiber and 1A material, and then wet kneaded. There is a method of obtaining a thin and firm porous body by agglomerating and then firing the obtained paper-formed/t-shaped material. However, in this method, in order to obtain high porosity, the content of the wood bulb is large, and since V-alumina is used, the sintered material fX:? ! 1,500~1',6
It was necessary to fire at 00°C with a high Y product.

The present invention provides a ceramic material that is sufficiently tight, strong, has high porosity, and has labyrinth-like pores to eliminate or compensate for the above-mentioned drawbacks. As a method for manufacturing the porous body, the amount of R-lithium wood bulb added as a sinterable inorganic material is set at 3 to 15 cm, and the I-1 pores can be sintered at a lower temperature than the method using alumina. This is a method for producing an electrolyte tile for a fuel cell in which the ratio is 40 to 80% of the total volume of the sintered product.

As an electrolyte tile for fuel cells, alumina is secretive and has excellent sleep insulation properties. However, alumina reacts with lithium carbonate used as an electrolyte,
Changed to lithium aluminate. Therefore, in the present invention, lithium aluminate, which has the most stable structure among lithium aluminates, is produced by reacting lithium hydroxide or lithium salts with alumina, and then sintered. Used as an inorganic substance.

To explain in more detail below, sintering J/, 1 (1t5
As rock material, LIOII (, LLCOg, LiCf
', LL Sot 6 Nolithium j ma, γ-alumina with an active surface and a grain size that is similar to that of crystalline alumina. , OOOoC for 1 hour or more to reduce the reaction to 1μ or less before use.

r-Lithium alumina-1 was ball milled to reduce the particle size to l.
The reason for keeping it below p is the same as when sintering ceramics.
In electrolyte tiles for fuel cells as well, the sintering temperature is lowered as the particle size increases, thereby saving energy and increasing the strength of the sintered product. Also,
When electrolyte tiles for fuel cells are manufactured using monolithium aluminate with fine particle size, this tile has an I
It must be impregnated with carbonate such as -it CO3,I (= CO-.And in order for this tile to fill and retain carbonate in the pores, the diameter of the pores must be 01
The pores need to be on the order of ~1 micron, and making the particle size of the γ-lithium aluminate finer means making the pores of the electrolyte tile finer.

In order to function as a reinforcing material and obtain a porosity of 40 to 80, wood pulp is selected from among the fibers of each fin, and the amount of wood pulp added is determined based on the total weight of the notebook when drying before sintering. The manufacturing method for the zero sintered material, which has a content of 3 to 15% by weight, first consists of 1p, which is 3 to 15% by weight of fibers and a sinterable inorganic material.
γ-lithium aluminate powder 97~R with the following particle size
5i'jL@%, water is added in an amount of about 10 to 50 times the weight of the solid content, and wet-mixed to obtain water 1 suitable for papermaking.
Adjust to raw slurry. This aqueous slurry becomes acidic or alkaline due to the elution of excess lithium hydroxide or lithium salts, so in order to adjust the pH, an acidic or alkaline aqueous solution is added to adjust the pf-I to 7, and a flocculant and A surfactant is added to cause agglomeration, and a paper is formed using a paper-making machine to form a /-1.-shaped plate.

This is because the agglomerating agent causes the fibrous material and sinterable inorganic substance to coagulate, making it easier to form paper. -1+ In addition, the surfactant assists the coagulation of fibers, inorganic substances, and fibers and inorganic substances, and makes the surface of paper-shaped and plate-shaped objects uniform and smooth. Add to make it thicker.

This molded product is placed in a firing furnace and fired in an oxidizing atmosphere. Firing is carried out from room temperature to 30 to 80'C per hour (hereinafter simply 30 to 700'C) for 1 to 3 hours. This is because the wood bulb is burned and vaporized, creating a maze of pores. If the heating rate is less than 30°C/H, it will take a long time to heat up, and if it is more than 80°C/H, the wood valve will expand and the shape of the paper-made notebook or plate will deteriorate. It swells and loses its shape.Therefore, the heating temperature in the continuous room is 30 to 80 degrees.
°C/H is suitable. and 500 to 700 °C to burn and vaporize the wood pulp at 500 to 700 °C.
Hold at 0°C for 1-3 hours.

If the holding time is less than 1 hour, the burning and vaporization of the wood pulp will not be completed, and if the holding time is more than 3 hours, the time will be too long.
3 hours is appropriate. After that, the r-lithium aluminate is sintered at a temperature of 1,000 to 1,300℃.
The temperature is raised at 300℃/4 (1,000℃, and sintering is carried out.
Bake at ~1,300°C for 1 to 3 hours.

Sintering will not be completed at temperatures below 1,000℃, resulting in
．． At temperatures above 300°C, sintering progresses and the pores that have been created will collapse, so the sintering temperature should be set at 1,000°C or higher.
1.300°C is appropriate. Also, +, 000 to 1,3
This 1,000~3 hours is maintained at 00°C.
Although sintering is completed at 1,300°C, if the holding time is less than 1 hour, the strength will not be achieved and the shape will collapse; if the holding time is held for less than 3 hours, the result will not change, so 1 to 3 hours is required. Appropriate.

As described above, by using r-lithium aluminate with a particle size of p or less, it is possible to sinter at a lower temperature than 1, and moreover, when the amount of wood pulp is added in an amount of about 3 to 15% by weight, sintering is possible. A dense and strong electrolyte tile for fuel cells with a large ratio of 40 to 80 and a maze of pores can be produced.

Specific examples of the present invention will be described below. The content rates of substances in actual cases are all based on the weight ratio or tunxing ratio.

<Example 1> (Δ) Material recombination of γ-lithium aluminate □' Lithium hydroxide monohydrate Gravimetric ratio: (manufactured by Kanto Kagaku ■, reagent special grade) 5 (17<1+1
γ-Alumina 50 parts' (Sumitomo Aluminum Smelting (stock system, average particle size 8p)
) (50 parts of lithium hydroxide monohydrate and 50 parts of γ-alumina
Put it in a plastic bag of about 00m6, shake it around by hand for 10 minutes, dry mix it, put it in a crucible of about 300+yA, and put it in an electric furnace. From room temperature to 1,000°C at 200'C/H with flowing air if necessary in an oxidizing atmosphere.
Raise the temperature at step 4. The mixture is kept at 1,000°C for 2 hours and stone fired to react, and then allowed to cool in the furnace and cooled to room temperature.

The cooled roasted γ-lithium aluminate was heated to 30 (
The mixture is placed in a ball mill of about 1 mn and ground for 24 hours to give an average particle size of about 0.8 parts.

(B) Sample preparation r-Lithium aluminate (particle size 0.8p) 30 parts Wood pulp 5 parts Water 1,000 parts (C) Flocculant and surfactant Sulfuric acid band I5 water soluble 20 parts Polyacrylamide system Bulky child agglomeration cutting 02 aqueous solution 20
(Product name manufactured by Sanyo Chemical Co., Ltd. [The/Bo'JN-500J'
) Amphoteric surfactant 20% aqueous solution 5 parts (Lion Kiki product "Lipomi/LAJ") Pour 5 parts of water i, ooo and 5 parts of wood pulp into a 2 minute container and stir for 20 minutes to fully disperse in the water. Then, add 30 parts of stone-fired γ-lithium aluminate ground with a ball mill and stir for 1 minute to make a water and slurry.

This aqueous slurry becomes strongly alkaline with a pH of 13 or more as excess lithium ions are eluted into water. Then, add drops of dilute sulfuric acid (sulfuric acid: water - 20.1) that was prepared in advance to bring the pH to 7. Add 20 parts of sulfuric acid band (15% aqueous solution) prepared in advance to the solution, stir for 2 minutes, and check with a pH test paper that P. Separated polyacrylamide polymer flocculant (Su/Poly N-500 02C aqueous solution)
and 45 parts of an amphoteric surfactant (Lipomin LA 20 aqueous solution) were added and stirred for 1 minute to coagulate.

The sample strips agglomerated as described above are made into a paper sheet with a paper making machine, and are made into a notebook shape of 30 crn square and 2 dragons thick. After drying, put it in an electric furnace and heat it from room temperature at a rate of 50°C/) (with an oxidizing atmosphere and flowing air if necessary), and the wood pulp is burned out and aerated. The γ-lithium aluminate is sintered at 600°C for 2 hours, which is the temperature at which a labyrinth of pores are formed.
The temperature was raised at 200°C/H until the temperature of the electric furnace reached 1,
When it reaches 200℃, hold it at this temperature for 2 hours and turn it into r-
Electrolyte tiles for fuel cells were manufactured by sintering lithium aluminate.

<Example 2> (A) Material composition of r-lithium aluminate and l-lithium carbonate weight ratio □'~ (Made by Sumitomo Aluminum Smelting ■, average particle size 8μ)
(6) Sample preparation l'r-lithium aluminate (average particle size 0.8/I)
30 parts' Wood bulb 1 part 1 water 1,000 parts (C) Flocculant and surfactant sulfate 15% aqueous solution 20 parts Polyacrylamide polymer flocculant 02% aqueous solution:
+o part (Product name: Sanpo IJN-500J manufactured by Sanyo Chemical Co., Ltd.)
) Amphoteric surfactant 20% aqueous solution 3 sounds μ (Lion ■
Manufactured parts “Lipomi/LAJ” Set 1 (A) as above
(B) Using (C), a notebook-shaped electrolyte tile for fuel cells was obtained in the same manner as in Example I.

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, has high porosity, and has continuous pores like a labyrinth is produced.

In the present invention, the conventional thin, pore-free l) 'H'!
This method incorporates the advantages of both the method of producing a dense metal oxide and the method of producing a foamable porous material, and the porosity can be freely adjusted by adding pulp. In addition, the complicated processing steps after foaming with polyurethane, which is a problem in the production of ceramic foam, are eliminated, so the production process is streamlined. In addition, by using r IJ thiualuminate with a particle size of 1 p or less and using a small amount of wood nodules, a dense and strong ceramilas porous body can be obtained at a lower temperature, resulting in an energy saving effect.

In addition, it can be used in places that are subject to repeated expansion and contraction due to heat, places that are subject to stress, and in particular places that are subject to repeated stress, electrical stress, and mechanical stress, such as electrolyte tiles for fuel cells. Furthermore, since paper-making technology is used instead of forming notebook-like objects for baking, it is possible to continuously manufacture sheet-like objects of uniform thickness, and it is also possible to continuously produce sheet-like objects with a uniform thickness. Actual winding is possible within this range.

patent applicant

Claims (1)

[Claims] The sinterable inorganic material powder and the fibrous material are mixed to form an aqueous slurry, and the sorted material obtained by agglomeration and papermaking is fired to burn off the fibrous material and vaporize it to form a powder of the sinterable inorganic material. When producing a thin and dense porous body by sintering lithium hydroxide and/or lithium salts, r-A7? 1 hour or more at tα 1,000℃・
The baked product, which has been left to cool after firing, is ground in a ball mill, and 3 to 15 particles per weight are added to make the average particle size 1μ or less. Adjust the pH to 7, then add a flocculant and a surfactant to agglomerate, form paper, and bake at a temperature of 30 to 80℃ from room temperature.
The temperature was raised at ℃A (and held at 500-700'C for 1-3 hours, then the temperature was raised at 100-300℃/H, 1,000
1. A method for producing an electrolyte tile for fuel cells, which is maintained at ~1,300°C for 1 to 3 hours.