JPH0644990A - Molten carbonate type fuel cell - Google Patents

Abstract

PURPOSE:To reduce an outflow of an electrolyte in an electrolyte plate while suppressing an increase in internal resistance resulting from the outflow of the electrolyte and generation of gas crossover for attaining a longer life by making a porous substance contain a lithium complex oxide having the prescribed density. CONSTITUTION:A cell contains an anode (fuel electrode) 11, a cathode (air electrode) 12 and an electrolyte plate 13 arranged between the electrodes 11, 12. A unit cell consists of the anode 11, cathode 12 and electrolyte plate 13, and a plurality of unit cells are layered by interposing separators 14 between them. The electrolyte plate 13 contains a holding material for preventing outflow of an electrolyte liquefied at the time of high temperature operation and a reinforcing material to prevent generation of cracks at the time of temperature rise while a part or the whole thereof has the constitution wherein a porous substance consisting of an Li complex oxide having density 4.00g/cm<2> or more is impregnated with mixed alkaline carbonate which is an electrolyte, in a molten state. Lithium tantalate can be used as a lithium complex oxide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molten carbonate fuel cell, and more particularly to a molten carbonate fuel cell having an improved electrolyte plate sandwiched between a pair of conductive electrodes.

[0002]

2. Description of the Related Art The basic structure of a molten carbonate fuel cell is shown in FIG.
Shown in. Between an anode (fuel electrode) 1 and a cathode (air electrode) 2 which are a pair of conductive electrodes, an electrolyte plate 3 holding an electrolyte composed of an alkali carbonate is sandwiched and arranged. . Two housings 4a and 4b are brought into contact with the peripheral edges of both sides of the electrolyte plate 3,
The anode 1 and the cathode 2 are housed in a and 4b, respectively. Corrugated current collecting plates 5a and 5b are provided between the inner surface of the one housing 4a and the anode 1 and between the inner surface of the other housing 4b and the cathode 2, respectively.
Are arranged. A supply port 6 for supplying fuel gas (H ₂ , CO ₂ ) to the anode 1 and exhaust gas (CO ₂ , H ₂ O) are provided in the one housing 4 a in which the anode 1 is located. The exhaust ports 7 for exhausting the air are opened. In the other housing 4b in which the cathode 2 is located, a supply port 8 for supplying an oxidant gas (air, CO ₂ ) to the cathode 2 and an exhaust gas (N ₂ ) are exhausted. The respective exhaust ports 9 are opened.

In the molten carbonate type fuel cell shown in FIG. 1 described above, the mixed alkali carbonate in the electrolyte plate 3 is melted at a high temperature, and the fuel gas (H ₂ H ₂ is supplied to the anode 1 through the supply port 6 of the housing 4 a). , CO ₂ ) and oxidant gas (air, CO ₂ ) are supplied to the cathode ₂ through the supply port 8 of the housing 4b, and the reaction of the formula (1) below is performed by the anode 1 to the cathode 2 Then, the operation is performed by causing the reaction of the following equation (2). ^{_{H 2 + CO 3 2- → H}} 2 O + CO + 2e - … (1) 1/2 O ₂ + CO ₂ + 2e ⁻ → CO ₃ ^2- … (2)

By the way, the electrolyte plate used in the molten carbonate fuel cell is basically composed of an electrolyte composed of a mixed alkali carbonate, and a holding material for preventing the outflow of the electrolyte which becomes liquid during high temperature operation. , And a reinforcing material for preventing cracking at the time of temperature rise. Mixed alkali carbonates include Li ₂ CO ₃ , K ₂ CO ₃ and Na ₂ CO _3.
It is used in the form of a mixed salt of two or three of the three. As the holding material, γ having a particle size of 0.05 to 0.5 μm
-LiAlO ₂ and β-LiAlO ₂ are fine powders,
As the reinforcing material, LiAlO having a particle size of 10 to 100 μm
₂ are used respectively.

The electrolyte plate is made of carbonate ion (CO ₃ ^2- )
Not only is it mediated by the transfer of gas, but it also functions as a gas permeation barrier layer for preventing direct mixing of the reaction gas between the anode and cathode (gas crossover). In order to perform such a function, it is necessary that the electrolyte is sufficiently retained in the electrolyte plate. Outflow of electrolyte (electrolyte loss)
Not only causes an increase in internal resistance but also causes gas crossover.

Therefore, as a method for obtaining an electrolyte plate having an appropriate fine structure, a porous plate is previously formed from a holding material and a reinforcing material, and an electrolyte containing a mixed alkali carbonate is added to the porous plate. The matrix method of impregnating is widely used.

However, when the fine structure is changed during the operation of the fuel cell for a long time, there is a problem that the matrix method causes electrolyte loss and sufficient life characteristics cannot be obtained.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and reduces the outflow of the electrolyte in the electrolyte plate to increase the internal resistance due to the outflow of the electrolyte. An object of the present invention is to provide a long-lived molten carbonate fuel cell capable of suppressing the generation of gas crossover.

[0009]

The present invention relates to a molten carbonate fuel cell provided with an electrolyte plate in which an electrolyte composed of a mixed alkali carbonate is impregnated in a porous body containing a holding material and a reinforcing material. The mass has a density of 4.00 g / cm ^3.
A molten carbonate fuel cell is characterized by containing the above lithium composite oxide particles. Hereinafter, a molten carbonate fuel cell according to the present invention will be described in detail with reference to FIGS. 2 and 3.

The molten carbonate fuel cell of the present invention is
A cathode (fuel electrode) 11, a cathode (air electrode) 12, and an electrolyte plate 13 arranged between these electrodes 11, 12 and holding an electrolyte. These nodes 11 and 1
2 and the electrolyte plate 13 are used as a unit cell, and a plurality of unit cells are laminated with a separator 14 interposed therebetween. The pair of opposite edges of the anode 11 arranged on the upper surface of the electrolyte plate 13 are positioned inside the edge of the electrolyte plate 13 to a desired distance, and the anode 11 is not present. Edge seal plates 15 a are arranged between both edges of the electrolyte plate 13 and the separator 14. The pair of edges of the cathode 12 arranged on the lower surface of the electrolyte plate 13 and orthogonal to the edge seal plate 15a are the electrolyte plate 1 and
An edge seal plate 15b is disposed between the separator 14 and both edges of the electrolyte plate 13 which is located inside the edge of the electrolyte plate 3 to a desired distance and does not have the cathode 12. ing. In the space (fuel gas distribution space) defined by the anode 11, the separator 14 and the edge seal plate 15a, a conductive perforated plate 16a and a corrugated plate 17a as current collector plates are provided. -The layers are sequentially stacked from the side of the door 11. The space defined by the cathode 12, the separator 14 and the edge seal plate 15b (oxidant gas flow space) is a perforated plate 1 having conductivity as a current collector plate.
6b and a corrugated plate 17b are sequentially laminated from the cathode 12 side. A plurality of such unit cells are separated by the separator 14.
Manifolds 19 each having a frame-shaped flange 18 are disposed on the four side surfaces of the stack power generation elements that are stacked with the frame sandwiched therebetween. Further, frame-shaped manifold seal plates 20 are respectively interposed between the four side surfaces of the stack power generation element and the flange 18 of the manifold 19. In the manifold (not shown) corresponding to the side surface of the power generation element where the fuel gas distribution space is exposed,
A supply pipe 22 for supplying the fuel gas 21 is attached. Manifold 19 on the opposite side of this supply pipe 22
A gas discharge pipe 23 is attached to the. Further, the oxidant gas 24 is provided in the manifold (not shown) corresponding to the side surface of the power generation element where the oxidant gas flow space is exposed.
A supply pipe 25 for supplying the water is attached. A gas exhaust pipe 26 is attached to the manifold 19 on the opposite side of the supply pipe 25. The electrodes 11 and 12 are made of, for example, a nickel base alloy or a sintered body of porous nickel base alloy. The separator 14,
Edge seals 15a, 15b, perforated plates 16a, 16b
The corrugated plates 17a and 17b are made of, for example, stainless steel.

As the fuel gas 21, for example, a mixed gas of hydrogen (H ₂ ) and carbon dioxide (CO ₂ ) can be used. As the oxidant gas 24, for example, air or a mixed gas of oxygen (O ₂ ) and carbon dioxide (CO ₂ ) can be used.

The electrolyte plate 13 contains a holding material for preventing the outflow of the electrolyte, which becomes a liquid during high temperature operation, and a reinforcing material for preventing the occurrence of cracks at the time of temperature rise. All have a density of 4.00 g / cm ^3. For example, a porous body having the porosity of 40 to 65% made of the above lithium composite oxide is impregnated with a mixed alkali carbonate as an electrolyte in a molten state.

Examples of the mixed alkali carbonate include lithium carbonate (Li ₂ CO ₃ ) and potassium carbonate (K ₂ C).
O ₃ ) mixture, Li ₂ CO ₃ and sodium carbonate (Na
Mixture of ₂ CO _3, Li ₂ CO ₃ and K ₂ CO ₃ and Na ₂
Examples thereof include a mixture of CO ₃ .

In the porous body, the lithium composite oxide has a particle diameter of 0.5 μm or less (preferably 0.05 to 0.5 μm).
It is desirable to include at least as a holding material in the form of fine powder of m). Specifically, it has the following form.

(A) Fine powder (holding material) of the lithium composite oxide having a particle size of 0.05 to 0.5 μm, and a particle size of 10
A porous body composed of the powder (reinforcing material) of the lithium composite oxide having a particle size of ˜100 μm. That is, this porous body is composed only of the lithium composite oxide.

(B) Fine powder (holding material) of the lithium composite oxide having a particle size of 0.05 to 0.5 μm, and a particle size of 10
A porous body composed of ˜100 μm LiAlO ₂ powder (reinforcing material).

(C) Fine powder of the lithium composite oxide having a particle size of 0.05 to 0.5 μm and LiAl _a having the same particle size.
O _b (0.89 ≦ a ≦ 1.11, 1.80 ≦ b ≦ 2.2
0; hereinafter, simply referred to as LiAl _a O _b and omitting the description of a and b), and a fine powder (holding material) of 10 to 10
A porous body composed of 100 μm LiAl _a O _b powder (reinforcing material). In the porous bodies (a) to (c), the holding material is 40% by weight or more, more preferably 50% by weight or more.
It is desirable that the content be at least wt%.

In the porous bodies (b) and (c), the fine powder of the lithium composite oxide having a particle size of 0.05 to 0.5 μm functioning as a holding material is 5% by weight or more in the porous body. , More preferably 10% by weight or more. The reason is that when the content of the fine powder of the lithium composite oxide is less than 5% by weight, it becomes difficult to prevent the agglomeration of the holding material, and the dispersion stability of the holding material in the molten carbonate is improved. It is difficult to do. In the porous bodies (b) and (c), a part of the lithium composite oxide is allowed to be contained in the powder having a particle size of 10 to 100 μm which functions as a reinforcing material.

The dense particles contained in the porous bodies (a) to (c)
Degree is 4.00 g / cm³ With the above lithium composite oxide
For example, LiTaO₃(Density 7.30 g / c
m³ ), Li₃TaO_Four(Density 8.22 g / cm³ )
Which lithium tantalate, LiNbO₂(Density 5.7
3 g / cm³ ), LiNb₃O₈(Density 5.03 g / c
m³ ), LiNbO₃(Density 4.63 g / cm³ )Such
Lithium niobate and the like can be mentioned. this
These lithium composite oxides may be used alone or in combination of two or more.
You may mix and use it.

L contained in the porous bodies (b) and (c)
Examples of iAl _a O _b include γ-LiAlO ₂ and β-
LiAlO ₂ can be mentioned. The LiAl _a O _b fine powder that functions as the holding material has an initial specific surface area of 7 to 40 m ² per 1 g. It is desirable to use the one.
The electrolyte plate described above is manufactured, for example, by the following method.

(1) First, the density is 4.00 g / cm ^3. The above lithium composite oxide and LiAl _a O _b, which is blended as necessary, are used as _a holding material having a particle size of 0.05 to 0.5 μm and an organic solvent together with an organic binder as a reinforcing material having a particle size of 10 to 100 μm. Mix in the presence. Examples of the organic binder used here include polyvinyl butyral, dibutyl phthalate, and acrylic resin. Examples of the organic solvent include alcohol, toluene, xylene, methyl ethyl ketone, and the like. Subsequently, the mixture is molded into a green sheet by a normal sheet forming method (for example, doctor blade method, calendar roll method, strip casting method, cold extrusion method, etc.), and then degreased to obtain a predetermined porosity. A porous body having is prepared. On the other hand, an electrolyte composed of a mixed alkali carbonate is formed into a sheet by the same method as that for the porous body to produce a sheet-like material. Next, an electrolyte plate is manufactured by stacking the sheet-shaped material on the porous body, melting the sheet-shaped material, and impregnating the porous body.

(2) The electrolyte plate prepared by the method (1) is placed between an anode and a non-impregnated cathode which are previously impregnated with an electrolyte composed of a mixed alkali carbonate, and the unit cell shown in FIG. After stacking a plurality of unit cells with a separator interposed therebetween to form a stack power generation element, a manifold is attached to four side surfaces of the power generation element to assemble a fuel cell.

[0023]

According to the present invention, in an electrolyte plate obtained by impregnating a porous body containing a holding material and a reinforcing material with an electrolyte composed of a mixed alkali carbonate, the density of the porous body is 4.00 g /
cm ³ By containing the above lithium composite oxide, particularly at least as a holding material in the form of a fine powder having a particle size of 0.5 μm or less, during operation due to the property of being difficult to aggregate due to the density of the lithium composite oxide. It is possible to suppress the outflow of the electrolyte (electrolyte loss) by suppressing the grain growth of the holding material in step 1, and it is possible to suppress the increase in the resistance of the electrolyte plate and the occurrence of crossover due to the electrolyte loss. Therefore, it is possible to obtain a long-lived molten carbonate fuel cell that can be operated for a long time.

[0024]

EXAMPLES Examples of the present invention will be described in detail below. Examples 1-6

First, the particle size is 0.2 to 2 μm and the density is 7.30.
g / cm ³ Fine powder of lithium tantalate with the same particle size and density of 4.63 g / cm ³ Of lithium niobate powder (all holding materials), lithium tantalate powder having a particle diameter of 20 to 60 μm, and lithium niobate powder having the same particle diameter (all reinforcing materials) in the alumina pot at the weight ratio shown in Table 1 below. And mixed with toluene, polyvinyl butyral and dibutyl phthalate for 20 hours to prepare 6 kinds of slurries. Subsequently, each of the above-mentioned slurries was spread on a carrier sheet to obtain a matrix green sheet having a thickness of 0.5 mm. After that, each of the matrix green sheets was degreased in the air to prepare six kinds of porous bodies.

Then, using a mixed alkali carbonate (Li ₂ CO ₃ ; 62 mol%, K ₂ CO ₃ ; 38 mol%) as an electrolyte, a slurry is prepared in the same manner as the porous body,
A sheet-like material was obtained by developing it on a carrier. Next, impregnating the porous body with the mixed alkali carbonate by stacking the sheet bodies on the respective porous bodies and raising the temperature to 550 ° C. to bring the sheet bodies into a molten state. 6 types of electrolyte plates having a thickness of 0.5 mm were manufactured by. Comparative Example 1

Specific surface area of 10 to 20 m ² / G of γ-lithium aluminate (γ-LiAlO ₂ ) fine powder (holding material) and γ-lithium aluminate powder of 20 to 60 μm particle size (reinforcing material) were put in an alumina pot at the weight ratio shown in Table 1 below. A porous body was prepared in the same manner as in Examples 1 to 6 except that a slurry prepared by wet mixing with toluene, polyvinyl butyral, and dibutyl phthalate for 20 hours was used. A sheet-like material similar to that in Examples 1 to 6 was placed on this porous body to raise the temperature to 550 ° C. to bring the sheet-like material into a molten state to impregnate the porous body with the mixed alkali carbonate. Thickness of 0.5m
m electrolyte plate was produced. Comparative example 2

Specific surface area of 10 to 20 m ² / G γ-lithium aluminate fine powder and particle size 0.2-2 μm, density 3.62 g / cm ^3. Lithium zirconate fine powder of (1) (retaining material) and lithium aluminate powder (reinforcing material) having a particle size of 20 to 60 μm were put in an alumina pot at a weight ratio shown in Table 1 below, and were added together with toluene, polyvinyl butyral and dibutyl phthalate. Porous bodies were produced in the same manner as in Examples 1 to 6 except that the slurry prepared by wet mixing for 20 hours was used. Example 1 on this porous body
~ 6 sheet-like material is piled up and the temperature is raised to 550 ° C to bring the sheet-like material into a molten state so that the mixed alkali carbonate is impregnated into the porous body to form a sheet having a thickness of 0.5 mm. An electrolyte plate was manufactured.

Each of the electrolyte plates of Examples 1 to 6 and Comparative Examples 1 and 2 was heated to 700 ° C. in an electric furnace and cooled, and then acetic acid solution (10 vol% glacial acetic acid, 10 vol% acetic anhydride, 80% ethanol). The mixed alkali carbonate is eluted by immersing it in a plate and the fine structure is observed with a scanning electron microscope.
The time until the particles of μm appeared by aggregation was examined. This value is also shown in Table 1 below as a guide for the deterioration characteristics of the electrolyte plate.

Further, each electrolyte plate of Examples 1 to 6 and Comparative Examples 1 and 2 and an anode made of nickel base alloy.
The molten carbonate fuel cell shown in FIGS. 2 and 3 described above was assembled using a separator, a cathode, a separator made of stainless steel, an edge seal plate, a perforated plate, and a corrugated plate. A mixed gas of 80 vol% H ₂ and 20 vol% CO ₂ as a fuel gas was supplied to the anode of each fuel cell, and 70 vol% air and 30 vol CO ₂ as an oxidant gas were supplied to the cathode.
% Of mixed gas, 150mA at 650 ° C
/ Cm ² The power generation test was performed under the load conditions of. In the power generation test, continuous operation was performed for 5000 hours, and the battery performance and the amount of electrolyte loss after 5000 hours had elapsed were examined. The results are also shown in Table 1 below.

[0031]

[Table 1]

As is clear from Table 1 above, the density is 4.
00 g / cm ³ The electrolyte plates of Examples 1 to 6 having the porous bodies containing lithium tantalate and lithium niobate, which are the above lithium composite oxides, as a holding material and a reinforcing material, have a growth time of 5 μm particles of the lithium composite oxide. The electrolyte plate of Comparative Example 1 having a porous body containing no and the density was 3.62 g / cm ^3. It can be seen that it is much longer than the electrolyte plate of Comparative Example 2 having a porous body containing lithium zirconate, which is the lithium composite oxide, as a holding material. Further, in the molten carbonate fuel cells incorporating the electrolyte plates of Examples 1 to 6, the operating potential drop was smaller than that of the fuel cells incorporating the electrolyte plates of Comparative Examples 1 and 2,
It can also be seen that the electrolyte loss is small. Examples 7-12

First, a lithium tantalate fine powder having a particle size of 0.2 to ₂ μm, a lithium niobate fine powder having the same particle size (both are holding materials), and a lithium aluminate (LiAlO ₂ ) powder having a particle size of 20 to 60 μm. (Reinforcing material) was placed in an alumina pot in the weight ratio shown in Table 2 below, and 2 together with toluene, polyvinyl butyral, and dibutyl phthalate.
Wet mixing was performed for 0 hours to prepare 6 kinds of slurries. Subsequently, each of the above-mentioned slurries was spread on a carrier sheet to obtain a matrix green sheet having a thickness of 0.5 mm. After that, each of the matrix green sheets was degreased in the air to prepare six kinds of porous bodies.

Then, using a mixed alkali carbonate (Li ₂ CO ₃ ; 62 mol%, K ₂ CO ₃ ; 38 mol%) as an electrolyte, a slurry is prepared in the same manner as the porous body,
A sheet-like material was obtained by developing it on a carrier. Next, impregnating the porous body with the mixed alkali carbonate by stacking the sheet bodies on the respective porous bodies and raising the temperature to 550 ° C. to bring the sheet bodies into a molten state. 6 types of electrolyte plates having a thickness of 0.5 mm were manufactured by.

The electrolyte plates of Examples 7 to 12 were replaced with those of Examples 1 to 1.
The microstructure was observed with a scanning electron microscope in the same manner as in 6,
The time taken for particles having a diameter of 5 μm to appear by aggregation was examined. This value is also shown in Table 2 below as a guide for the deterioration resistance of the electrolyte plate.

As in Examples 1 to 6, the molten carbonate fuel cells shown in FIGS. 2 and 3 were assembled using the electrolyte plates of Examples 7 to 12 and the cell performance after 5000 hours had elapsed. And the amount of electrolyte loss was investigated. The results are also shown in Table 2 below. In Table 2 below, Comparative Example 1 described above,
The time until the particles of 2 μm in diameter of 5 μm appeared by aggregation, the molten carbonate fuel cell was assembled, and the cell performance and the amount of electrolyte loss after 5000 hours were shown together.

[0037]

[Table 2]

As is clear from Table 2, the density is 4.
00 g / cm ³ The electrolyte plates of Examples 7 to 12 having the porous bodies containing lithium tantalate and lithium niobate, which are the above lithium composite oxides, as a holding material did not contain the lithium composite oxides in the growth time of particles of 5 μm. The electrolyte plate of Comparative Example 1 having a porous body and the density of 3.62 g / cm ³ It can be seen that it is much longer than the electrolyte plate of Comparative Example 2 having a porous body containing lithium zirconate, which is the lithium composite oxide, as a holding material. Further, the molten carbonate fuel cells incorporating the electrolyte plates of Examples 7 to 12 have a smaller operating potential drop and a smaller electrolyte loss than the fuel cells incorporating the electrolyte plates of Comparative Examples 1 and 2. I understand. Examples 13-20

First, the specific surface area is 10 to 20 m ^2. / G γ
-Lithium aluminate (γ-LiAlO ₂ ) fine powder,
Lithium tantalate fine powder having a particle diameter of 0.2 to 2 μm and lithium niobate fine powder having the same particle diameter (both are holding materials), and lithium aluminate (LiAlO ₂ ) powder having a particle diameter of 20 to 60 μm (reinforcing material) are used. The mixture was placed in an alumina pot in the weight ratio shown in Table 3 below, and wet mixed with toluene, polyvinyl butyral and dibutyl phthalate for 20 hours,
Eight slurries were prepared. Subsequently, each of the above-mentioned slurries was spread on a carrier sheet to obtain a matrix green sheet having a thickness of 0.5 mm. Then, each of the matrix green sheets was degreased in the atmosphere to prepare eight kinds of porous bodies.

Then, using a mixed alkali carbonate (Li ₂ CO ₃ ; 62 mol%, K ₂ CO ₃ ; 38 mol%) as an electrolyte, a slurry was prepared in the same manner as the porous body,
A sheet-like material was obtained by developing it on a carrier. Next, impregnating the porous body with the mixed alkali carbonate by stacking the sheet bodies on the respective porous bodies and raising the temperature to 550 ° C. to bring the sheet bodies into a molten state. Was used to produce eight types of electrolyte plates having a thickness of 0.5 mm.

Each of the electrolyte plates of Examples 13 to 20 was used in Example 1.
The fine structure was observed with a scanning electron microscope in the same manner as in ~ 6 to examine the time until particles with a diameter of 5 µm appeared due to aggregation. This value is also shown in Table 3 below as a guide for the deterioration resistance of the electrolyte plate.

As in Examples 1 to 6, the molten carbonate fuel cells shown in FIGS. 2 and 3 were assembled using the electrolyte plates of Examples 13 to 20 and the cell performance after 5000 hours had elapsed. And the amount of electrolyte loss was investigated. The results are also shown in Table 3 below. In addition, in Table 3 below, the time until particles of 5 μm in diameter of the above-mentioned Comparative Examples 1 and 2 appear by agglomeration, the molten carbonate fuel cell was assembled, and the cell performance and the amount of electrolyte loss after 5000 hours were shown together. did.

[0043]

[Table 3]

As is clear from Table 3, the density is 4.
00 g / cm ³ The electrolyte plates of Examples 13 to 20 having the porous bodies containing lithium tantalate and lithium niobate, which are the lithium composite oxides described above, as a part of the holding material, had a growth time of 5 μm particles of the lithium composite oxides. The electrolyte plate of Comparative Example 1 having a porous body containing no and the density was 3.62 g / cm ^3. It can be seen that it is much longer than the electrolyte plate of Comparative Example 2 having a porous body containing lithium zirconate, which is the lithium composite oxide, as a holding material. Further, in the molten carbonate fuel cells incorporating the electrolyte plates of Examples 13 to 20, the operating potential drop was smaller and the electrolyte loss was smaller than the fuel cells incorporating the electrolyte plates of Comparative Examples 1 and 2. I understand.

In particular, the electrolyte plates of Examples 13 to 15 and 17 to 19 each having a porous body containing lithium tantalate and lithium niobate as a holding material in an amount of 5.0% by weight or more of the total amount were 5 μm in particle growth time. It is understood that when the fuel cell is incorporated into a molten carbonate fuel cell, the drop in operating potential of the fuel cell can be made extremely small and the electrolyte loss can be remarkably reduced.

[0046]

As described above in detail, according to the present invention, the outflow of the electrolyte in the electrolyte plate can be reduced, the internal resistance accompanying the outflow of the electrolyte can be prevented from increasing, and the gas crossover can be prevented from occurring. It is possible to provide a long-life molten carbonate fuel cell that can be operated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the basic structure of a molten carbonate fuel cell.

FIG. 2 is a perspective view showing a general configuration of a molten carbonate fuel cell according to the present invention.

3 is an enlarged perspective view of a main part of the fuel cell of FIG.

[Explanation of symbols]

11 ... Anode, 12 ... Cathode, 13 ... Electrolyte plate, 1
4 ... Separator, 19 ... Manifold, 21 ... Fuel gas, 24 ... Oxidizer gas.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Tateishi 1 Komukai Toshiba Town, Komukai-ku, Kawasaki-shi, Kanagawa Toshiba Research & Development Center (72) Inventor Toshimatsu Toshimatsu Komukai, Kawasaki-shi, Kanagawa Prefecture Toshiba Town No. 1 Inside Toshiba Research and Development Center

Claims (2)

[Claims] 1. A molten carbonate fuel cell comprising an electrolyte plate in which a porous body containing a holding material and a reinforcing material is impregnated with an electrolyte composed of a mixed alkali carbonate, and the porous body has a density of 4.00 g. / Cm ³ A molten carbonate fuel cell comprising the above lithium composite oxide. 2. The molten carbonate fuel cell according to claim 1, wherein the lithium composite oxide is lithium tantalate.