JPH0541226A - Fused carbonate type fuel cell and filler used therefor - Google Patents

Abstract

PURPOSE:To prevent a drop of cell characteristic due to a crack of an electrolytic layer at a portion of gap between the seal portion and the electrode of a fused carbonate type fuel cell and provide a stabilized and reliable fused carbonate type fuel cell and a filler used therefor by taking such measures that no gap is produced between the seal portion and the electrode of the fuel cell. CONSTITUTION:The seal portion and the gap of the boundary portion between a fuel-side electrode and an oxidant-side electrode in a fused carbonate type fuel cell are filled with a filler 10. The filler 10 to be used therefor is mainly composed of metal and ceramics and contains a solvent, a plasticizer, a dispersant, and a binder.

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 structure of a boundary between a seal and an electrode end and a filler used for the boundary.

[0002]

2. Description of the Related Art FIG. 5 is a perspective view showing a main part of a cell structure of a conventional molten carbonate fuel cell. In FIG. 5, (1) shows, for example, a sintered body containing nickel metal powder as a main component. Is a porous fuel-side electrode (hereinafter referred to as an anode), (2) is, for example, a porous oxidant-side electrode (referred to as a cathode) made of a nickel sintered body or a NiO sintered body, and (3) is LiAlO ₂ An electrolyte layer composed of a porous structure containing as a main component a carbonate such as Li ₂ CO ₃ or K ₂ CO ₃ , which is interposed between the anode (1) and the cathode (2). Configure the battery.
(4a) and (4b) are corrugated plate-shaped gas channel plate made of stainless steel or the like that also serves as a gas channel for the fuel and the oxidizer and a current collecting function,
(5) is a separator plate for separating the fuel gas flow path and the oxidant gas flow path, (7a) and (7b) is a seal part provided at both ends parallel to the gas flow direction of the separator plate (5) Is. In the figure, arrow X indicates the flow direction of the fuel gas, and Y indicates the flow direction of the oxidant gas.

The operation of the molten carbonate fuel cell, which is a laminated body in which a plurality of unit cells and separator plates having the above construction are laminated, will be described. A fuel cell is a device that obtains electricity by directly converting the chemical energy of a fuel gas such as hydrogen and an oxidant gas such as air into electrical energy by an electrochemical reaction. After stacking a plurality of unit cells having the above structure, a constant surface pressure (eg, 2 kg / cm ² ) is applied in the vertical direction in order to improve electrical contact and improve the sealing property of fuel or oxidant gas. After adding and tightening,
After a temperature rising process, a steady operation is started at a temperature of 650 ° C.

FIG. 6 is an exploded perspective view of a battery structure centering around the electrolyte layer (3) of a conventional battery, and FIG. 7 is a cross-sectional view of the main part taken along the line IXV-IXV in FIG.

The electrolyte layer (3) comprises an anode (1) and a cathode (2)
It is sandwiched between the anode and the cathode, and a constant surface pressure is applied in the stacking direction.
a), the width of the anode (1) or the cathode (2) is smaller than the dimension between the seal parts (7a-7a) provided along (4b) or (7b-7b). A gap is created at the boundary portions (8a) and (8b) between the seal portions (7a) and (7b) and the anode (1) or the cathode (2). In order to prevent a gap, the width between the anode (1) or the cathode (2) and the seal (7a-7a, 7
It is only necessary to increase the dimensional accuracy (b-7b), but there are some parts that cause dimensional errors as the size increases as the capacity of the battery increases. For example, a thin stainless steel separator
In the part where the long and narrow seal parts are welded to both ends of (5), thermal distortion may occur and the seal part may be deformed such as curving in the length direction, and the anode (1) or cathode (2) may be attached to itself. When combined, there will be a part that creates a gap at the boundaries (8a) and (8b).

By the way, the electrolyte layer (3) is a thin sheet having a thickness of about 0.3 to 2.0 mm, which is made of a mixture of LiAlO ₂ powder and an organic substance (for example, a fixing agent, a viscous agent and a dispersant). And the thermal decomposition start temperature (about 100
(° C) or higher, the mechanical strength tends to decrease, and it has a very brittle property.

[0007]

Since the conventional molten carbonate fuel cell is constructed as described above, the boundary portion (8
When the gaps (a) and (8b) are generated, the electrolyte layer (3) having brittle properties has cracks (9) along the gaps (8a) and (8b) in the boundary portion, and fuel gas and oxidant gas are generated. However, there is a problem in that a so-called crossover phenomenon occurs, and battery characteristics are significantly deteriorated.

The present invention has been made in order to solve the above problems, and by taking measures to prevent a gap from being formed between the seal portion and the electrode, cracks in the electrolyte layer at that portion are caused. An object of the present invention is to provide a molten carbonate fuel cell which prevents deterioration of cell characteristics, has stability and reliability, and a filler used for the same.

[0009]

A unit cell having a fuel-side electrode (anode) and an oxidant-side electrode (cathode) facing each other with an electrolyte layer interposed therebetween according to the present invention, and a unit cell facing the fuel-side electrode. The fuel gas flow channel and the oxidant gas flow channel provided facing the oxidant side electrode are separated, and a seal portion is provided at an end portion along each of the gas flow channels so that the inside and outside of the battery In a molten carbonate fuel cell in which separator plates to be separated and sealed are alternately laminated to form a laminated body, a filler is filled in a gap at a boundary portion between the seal portion and the fuel side electrode and the oxidant side electrode. Characterize.

Further, the molten carbonate fuel cell filling material according to the present invention contains a metal and a ceramic as main components, a solvent,
It is characterized by containing a plasticizer, a dispersant and a binder.

[0011]

The molten carbonate fuel cell of the present invention has a structure in which the gap between the seal portion and the electrode is eliminated to prevent crack damage to the electrolyte layer at the portion corresponding to the above-mentioned boundary portion. You can

[0012]

EXAMPLE 1 An example of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing a boundary portion between a seal portion and an electrode end portion of a molten carbonate fuel cell according to an embodiment of the present invention, which is the same as the cross section taken along line IXV-IXV of FIG. It is a part. In FIG. 1, (1), (3), (4), (5), (7)
Is the same as the conventional battery described above. (10) is the seal
It is a filling material filled in the gap formed at the boundary between (7) and the electrode (1).

Next, the material of the filler (10) and the filling method will be described. It is preferable that the material of the filler (10) is suitable for the atmosphere, temperature, electrolyte resistance, etc. of the filling portion, and Ni, C in the case of hydrogen atmosphere.
u, Co, and other metal simple substance powders or alloy powders containing them as the main component are the main components, and a solvent, plasticizer, dispersant,
As a putty-like material formed by mixing a binder or a material that is not so restricted by the atmosphere, Al ₂ O ₃ , ZrO ₂ , LiAl
The main component is ceramic powder such as O ₂ and the solvent,
A putty material prepared by mixing a plasticizer, a dispersant and a binder is suitable.

More specifically, the main component (raw material) of the filler is N
i powder, Co powder, Cu powder, Ni-Al alloy powder, γ-LiA
lO ₂ powder, α-Al ₂ O ₃ powder, at least one such ZrO ₂ powder
Consists of seeds, the solvent contains at least one of tetrachloroethylene, ethanol, isobutanol, water, etc., the plasticizer contains two kinds of polyalkylene glycol and alkyl phthalate, the dispersant consists of fish oil etc.,
The binder is selected from polyvinyl butyral, carboxymethyl cellulose and the like.

The main component of the filler is Ni-Al.
When alloy powder is used, the Al content of the alloy is 1 to 5
It is preferably within the range of 0% by weight.

As one embodiment, for example, Ni on the anode side
A description will be given in which the main component is Al- (5%) alloy powder, and the filler is made into a soft putty by mixing a solvent, a plasticizer, a dispersant, a binder and the like. Above seal part
If the gap formed at the boundary between (7) and anode (1) is small, the electrolyte layer (3) is less likely to be damaged, but if it becomes a large gap, it will be locally deformed along the gap. Or, there is a greater possibility of cracks. In order to reduce the gap, for example, the dimensional accuracy of the width between the seals on both sides and the width of both ends of the anode (1) may be increased, but the size increases as the battery size increases, and the number of cells increases. If so, some may cause a dimensional error.

In the present invention, the filler (10) is used for the above-mentioned gap caused by the dimensional error of about 0.5 to 2 mm.
The properties required for the filling material (10) are that it is easy to fill the above-mentioned narrow gaps, and shrinks after filling due to temperature, compression force or gas atmosphere. It is necessary that the expansion does not differ greatly from that of the peripheral members. Therefore, in the examples described below, the filling material corresponding to each of the anode electrode side, the cathode electrode side, and both electrode sides will be described.

[0018]

[Table 1]

Table 1 shows the components and component ratios of the filler to be filled in the gaps formed on the anode side of the present invention. The main component is Ni-Al (5%) powder having an average particle size of about 4 μm. ,
Three kinds of solvents such as tetrachloroethylene, two kinds of plasticizers such as polyalkylene glycol, a dispersant composed of fish oil, a binder composed of polyvinyl butyral, etc. are mixed at a ratio shown in Table 1 and stirred to give a soft putty-like form. Make the filler (10a).

Next, a method for filling the gap (8) with the filling material (10a) will be described. FIG. 2A is a cross-sectional view showing a method of filling the gap on the anode side using a filling jig. The metal fittings (11a) and (11b) having L-shaped cross sections are made to face each other.
a), (11b) side plates (12a), (12b) on both sides of the saucer as a saucer on the base plate (13) with a slit (8) maximum width dimension (for example 3mm) Install. Side plate (12a),
(12b) is fixed to the metal fitting (11b), and the metal fitting (11b) is fixed to the base plate (13). The metal fitting (11a) can be freely moved on the base plate (13) by loosening the fixing screw (14), and the pan width dimension W can be adjusted according to the size of the gap (8). When filling,
The filling jig is set at the position of the gap (8), the L-shaped metal fitting (11) is moved, and the pan width dimension W is adjusted to the width of the gap (8). Next, the filling material (10) is placed in the saucer in an amount equivalent to the volume of the gap (8) and is pushed into the gap (8) of the filling material (10) with the pushing metal fitting (15) (in this case, the state of the gap, etc.). Therefore, it may be easier to fill it by dividing it into several times than filling the gap volume of filling material at once).

Further, as shown in FIG. 2 (b), a sheet in which a filler is added so that the anode (1) and the seal part (7) are slightly above the upper surface, and a polyester film or the like is coated with a release agent. Place (15) on the top surface of the filling part and press it from above with the metal fitting (16) so that the top surface of the filling material (10a) is flush with the top surface of the anode (1) and the top surface of the sealing part (7). ..

[0022]

[Table 2]

Further, the filling material for filling the gap (8b) on the cathode (2) side is composed of components similar to the cathode material,
The components and component ratios are shown in Table 2. Ni powder, which is the main raw material of this filler, has an average particle size of about 7 μm, and water and a binder are mixed and stirred to form a soft putty-like filler.
The filling method is the same as that on the anode side.

By the above method, the sealing part (7) and the anode
(1) or the cathode (2) is filled with the filler (10) to fill the gap, the single cell is laminated and assembled in the same battery configuration as before, and the surface pressure is applied 2-10 kg / cm ^2. Steady temperature 6
The temperature is raised to 50 ° C. and normal operation starts. During this temperature rising process, a solvent other than Ni-Al (5%) alloy powder, which is the main component of the filler,
Other components disappear by thermal decomposition, and the putty-like filler that was soft before the temperature rise maintains the hard property of the alloy powder.

As a result, the seal portion (7a) of the electrolyte layer (3),
Boundary (8a) between (7b) and anode (1) or cathode (2),
By preventing crack damage in (8b), deterioration of battery characteristics was eliminated, and a highly stable and reliable battery was obtained.

Example 2 In addition, the anode side filler of the above Example 1 was composed of N as a main component.
Although i-Al (5%) powder and a solvent, a plasticizer, a binder, and the like having a constant component ratio were used, the Al ratio of the Al alloy powder of the main component Ni-Al alloy powder and its main component (raw material) Powder), solvent,
A soft putty-like filler (10a) in which the ratio of all the components of the plasticizer, the dispersant, and the binder is set as shown in Table 3 may be used.

[0027]

[Table 3]

Example 3 The anode side filler of the above Examples 1 and 2 was an amorphous soft putty-like filler, but a slurry having the composition ratio shown in Table 4 was cast and formed. , And further press-molded into a sheet. Then, several kinds of different thicknesses are made according to the gap of the filling part, and a strip shape cut into the depth of the gap is used as the filling material on the anode (1) side.
It may be filled as shown in FIG. 3 as (10b).

[0029]

[Table 4]

Example 4 A slurry having the same component ratio (Table 3) as that shown in Example 3 above was formed into a sheet by the same method, and then about 1
A sheet harder than the filler of Example 3 was sintered by sintering at a temperature of 000 ° C. Then, several kinds with different thickness depending on the gap are made and cut into a size according to the depth of the gap, and a rectangular plate is filled as the anode side filler (10a) as shown in FIG. May be.

Example 5 Further, as shown in FIG. 4, a method using two kinds of fillers,
That is, after filling the rectangular packing material (10b), a small amount of the soft putty-like packing material (10a) shown in Examples 1 and 2 was used, and the packing material (10a) was prepared in the same manner as in Working Example 1. Top and anode
The filling method may be such that the upper surface of (1) or the seal portion (7) is flush with the same surface.

Example 6 Although 2 to 5 of the above examples were for the case of the filler on the anode side, as the filler on the cathode side, those having the component ratios shown in Table 5 were mixed and stirred. A soft putty-like filler may be used and may be filled in the same manner as in Example 1.

[0033]

[Table 5]

Example 7 In addition, the cathode side filler was prepared by forming a slurry having a composition ratio range shown in Table 6 and casting and further press forming into a sheet, and within a gap width dimension range. It is also possible to make several kinds having different thicknesses and fill them with strip-shaped fillers cut according to the depth of the gap.

[0035]

[Table 6]

Example 8 The filler made into a sheet in Example 7 above was sintered and hardened at a temperature of about 700 ° C., cut into strips and filled in the same manner as in Example 7 above. May be.

Example 9 Example 4 (FIG. 4) was prepared by filling the strip-shaped fillers shown in Examples 7 and 8 above and a small amount of the soft putty-like filler shown in Examples 1 and 6. It may be the same as the method shown in.

Example 10

[0039]

[Table 7]

The particle size shown in Table 7 is 0.1.
In the same manner as in Example 1 (FIG. 2), a soft filler obtained by mixing and stirring a mixture containing γ-LiAlO ₂ having a particle size of ˜2.0 μm as a main component was filled in both gaps on the anode side and the cathode side. May be.

Example 11

[0042]

[Table 8]

Further, materials having the component ratios shown in Table 8 were mixed and stirred to form a slurry, which was cast-molded,
Further, press molding is performed to make a sheet-shaped filler. And
It is also possible to make several kinds of this filler having different thicknesses according to the gaps, cut into a size according to the depth of the gaps, and make a strip shape to fill them as shown in FIG.

Example 12 Example 4 using the fillers of both Examples 10 and 11 above.
It may be filled by the method shown in FIG.

Example 13 Furthermore, the raw material powders γ-LiAlO ₂ shown in Tables 7 and 8 were replaced with either α-Al ₂ O ₃ or ZrO ₂ having a particle size of 0.1 to ₂ μm, and other materials were used. The same components may be manufactured and filled in the same manner as in Examples 10 to 12, and the same effects as those in the above Examples are obtained.

[0046]

As described above, according to the present invention, the gap between the seal portion and the end portion of the electrode is filled with the filler to eliminate the gap. This is effective in preventing deterioration of battery characteristics due to crack damage and obtaining a highly reliable battery.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts for filling the soft putty-like filler shown in Examples 1, 2, 6, 10, 13 of the present invention.

FIG. 3 is a cross-sectional view of essential parts filled with the sheet-like filler shown in Examples 3, 4, 7, 8, and 11 of the present invention.

FIG. 4 is a cross-sectional view of essential parts filled with both a sheet-like filler and a soft putty-like filler shown in Examples 5, 9, and 12 of the present invention.

FIG. 5 is a perspective view showing a part of the configuration of a conventional molten carbonate fuel cell.

FIG. 6 is an exploded perspective view showing a conventional molten carbonate fuel cell.

FIG. 7: IXV- of the conventional molten carbonate fuel cell of FIG.
It is an important section sectional view in a IXV line.

[Explanation of symbols]

 1 Anode 2 Cathode 3 Electrolyte Layer 4a Fuel Gas Flow Path 4b Oxidant Gas Flow Path 5 Separator Plate 7 Sealing Part 8a Boundary 8b Boundary 9 Crack 10 Filler

Claims (3)

[Claims] 1. A fuel-side electrode facing each other with an electrolyte layer interposed therebetween.
(Anode) and a single cell having an oxidant side electrode (cathode), and a fuel gas flow channel provided facing the fuel side electrode and an oxidant gas flow channel provided facing the oxidant side electrode. In a molten carbonate fuel cell that separates and constitutes a laminated body by alternately laminating separator plates that have a seal portion at the end portion along each of the dregs flow paths to separate and seal the inside and outside of the cell, A molten carbonate fuel cell, characterized in that a filler is filled in a gap at a boundary portion between the seal portion and the fuel-side electrode and the oxidant-side electrode. 2. A filler for a molten carbonate fuel cell, which is mainly composed of metal and ceramics and contains a solvent, a plasticizer, a dispersant and a binder. 3. The main component of the filler is Ni powder, Co powder, Cu
Powder, Ni-Al alloy powder, γ-LiAlO ₂ powder, α-Al ₂
It consists of at least one of O ₃ powder and ZrO ₂ powder, the solvent contains at least one of tetrachloroethylene, ethanol, isobutanol and water, the plasticizer contains two kinds of polyalkylene glycol and alkyl phthalate, and the dispersant is fish. The filler for a molten carbonate fuel cell according to claim 2, wherein the oil and the binder are any one of polyvinyl butyral and carboxymethyl cellulose.