JPS58129777A - Fuel battery - Google Patents

Abstract

PURPOSE:To obtain a mechanically strong electrolyte plate while improving the supporting force of an alkaline carbonate electrolyte by allowing said electrolyte to be supported on a uniform porous sintered body comprising long fiber ceramics and fine particle ceramics. CONSTITUTION:In a fuel battery, comprising an anode, a cathode, and an electrolyte plate for supporting an electrolyte arranged between said both electrodes, and electrochemically generating electricity by respectively feeding fuel and an oxidizing agent to a fuel chamber arranged on the anode side and to an oxidizing agent chamber arranged on the cathode side, a porous ceramics sintered body is made by suspending long fiber ceramics and fine particle ceramics into dispersions, filtrating said suspended solution via a screen, forming it into a plate shape while pressing it, and drying and sintering it, and alkaline carbonate is impregnated in said porous veramics sintered body. The long fiber ceramics are mixed in its ratio of 5-65wt% against the fine particle ceramics.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molten salt fuel cell, and more particularly to a molten salt fuel cell equipped with an electrolyte plate matrix that has excellent mechanical strength and is suitable for enhancing electrolyte retention.

There are two types of electrolyte plates for molten salt fuel cells: a paste type made by hot pressing a mixture of fine ceramic powder and an alkali carbonate, and a marsotas type made by impregnating a porous ceramic body with an alkali carbonate.

Paste-type electrolyte plates have difficulties in mass production and large-scale production, so matrix-type plates are currently attracting attention.

Porous sintered bodies as a matrix can be produced by molding by powder pressing, extrusion, slip casting, injection molding, green tape, etc., and heating and sintering. There are problems with electrolyte retention and mechanical strength,
Good battery performance cannot be obtained.

An object of the present invention is to improve the drawbacks of the prior art and provide a molten salt fuel cell having an electrolyte plate with improved retention of an alkali carbonate electrolyte and strong mechanical strength.

The gist of the present invention is to use an electrolyte plate formed by holding an alkali carbonate electrolyte in a homogeneous porous sintered body of long fiber ceramics and fine particle ceramics as an electrolyte plate for a molten salt fuel cell.

According to the present invention, the structure of long fiber ceramics and fine particle ceramics significantly improves electrolyte retention, increases bubble withstand pressure, prevents the talosover phenomenon of reaction gas, and prevents electrolyte from flowing into electrodes and other components. This has the advantage of suppressing

Other advantages of the present invention are that long-fiber ceramics exhibit their effectiveness as a core material, which improves mechanical strength, prevents cracks from occurring due to thermal cycles during manufacturing or operation, and provides long-term stability. This means that the FC battery performance can be maintained.

In addition, alumina is a long fiber ceramic.

Lithium aluminate, titania, zirconia.

Carbonized cane, etc., and the ratio of fiber length to fiber diameter is 10.
It's more than twice as good, more than 100 times more.

Fine particle ceramics are preferably alkali-resistant non-conductive fine powders, such as magnesia, zirconia, aluminum aluminate, and alumina.

Titania and the like can also be used if they are converted into a substance that is stable against molten carbonates. The particle size of the fine ceramic particles is suitably 10 μm or less, preferably 1 μm or less.

The ratio of long fiber ceramics to fine particle ceramics is preferably 5 to 65% by weight.

When the content of long fiber ceramics is less than 5%, it is less effective as a core material and no effective mechanical strength can be obtained. On the other hand, if it is 65% or more, the electrolyte holding power is weak and stable battery performance for a long time cannot be obtained.

A porous sintered body consisting of long fiber ceramics and fine particle ceramics creates a suspension in which the long fiber ceramics and fine particle ceramics are homogeneously dispersed.

It is filtered through a screen and formed into a predetermined shape, then pressed to adjust the desired thickness, density, and porosity, and fired to form a porous sintered body. Here, it is necessary to adjust the viscosity of the dispersion liquid in order to make a homogeneous suspension of long fiber ceramics and fine particle ceramics (4). Addition date: soc, p, s, more than 5000c, p,
s, it is preferable to adjust it to below. The press pressure for filtering with a screen varies depending on the desired thickness, density, and porosity, but is 1 kg/cIr12 to 1000 kg/
cm" is preferable. Firing causes bonding of long fiber ceramics and fine particle ceramics, increasing mechanical strength, and
The temperature at which a porosity of 0 to 70 VOt% can be obtained is 800.
~1600U is preferred.

An electrolyte plate can be prepared by sufficiently impregnating the pores of a porous sintered body made of long fiber ceramics and fine particle ceramics with an alkali carbonate electrolyte.

The present invention will be explained in more detail below with reference to Examples.

Example 1 Long fiber alumina (fiber diameter 1-5μ, fiber length 0.3-3m
) 20g and lithium aluminate powder (average a diameter 0.4
μ) 1% carboxymethylcellulose dissolved in ioog9
In addition to 21, stir thoroughly to disperse well, filter by suction with a Stareen filter as shown in Figure 1, dry, and then add 10
It was pressed at 0 kg/i and sintered at 1450 r for 3 hours.

The obtained sintered body measures 203×204 and has a thickness of 1.6 m.
The porosity was 49.5%. This was impregnated with 75 g of alkaline carbonate electrolyte to prepare an electrolyte plate.

Using the obtained electrolyte plate, a nickel porous electrode plate was used for the anode and cathode to construct a unit cell with an effective area of 30 mgφ, and the anode gas was 50% H, -N, and the cathode gas was 25% 02-25%. A mixed gas of CO2 and residual N2 was passed through the cell, and the battery performance was measured at 650C. At a current density of 100 mA/crn2VC, the initial battery voltage is 0.
76V, and 0.77V after 70 hours.

Example 2 Long fiber alumina (fiber diameter 1-5 μm, fiber length 0.3-3
rum) and 68 g of lithium carbonate were mixed and treated at 740C for 20 hours to synthesize fibrous lithium alumina). Add 50g of finely powdered lithium aluminate (average particle size 0.4μm) to this, add it to 3t of 0.65% carboxymethyl cellulose solution, stir the mixture optically, and filter the well-dispersed liquid into a screen filter as shown in Figure 1. It was filtered under suction, dried and pressed at 25 kg/cm2, and then sintered at 1580C for 5 hours. The obtained sintered body measures 201 x 202 mm, has a thickness of 1, has an 8-sided body, and has a porosity of 53%.
I failed.

This was impregnated with 85 g of alkaline carbonate electrolyte to prepare an electrolyte plate. Using the obtained electrolyte plate, battery performance was examined in the same manner as in Example 1. Current density 100 mA/C!
The battery voltage per n2;fv was 0.73 V at the initial stage and 0.75 V after 70 hours.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a screen filter. 1... Screen filter, 2... Screen, 3...
...Suspension, 4...Valve. 347-

Claims (1)

[Claims] 1. An anode, a cathode, and an electrolyte plate that holds an electrolyte disposed between both electrodes, and a fuel chamber and an oxidizing agent are disposed on the anode side and the cathode side, respectively. In a fuel cell that electrochemically generates electricity by being supplied to an oxidizer chamber provided, long fiber ceramics and fine particle ceramics are suspended in a dispersion liquid, and the suspension is passed through a suction tube. It is filtered, pressed into a plate shape, dried and sintered to create a porous ceramic sintered body.
A fuel cell characterized in that the porous ceramic sintered body is impregnated with an alkali carbonate. 2. The fuel cell according to claim 1, wherein the ratio of the long fiber ceramics to the fine particle ceramics is within the range of 5 to 65% by weight of the long fiber ceramics.