JPH0320970A - Removing method of binder in electrolyte plate in fuel cell - Google Patents

Abstract

PURPOSE:To quickly remove a binder at normal temperature without emitting an offensive smell by removing the binder in an electrolyte plate by circulating an organic solvent into a gas passage. CONSTITUTION:An electrolyte plate containing a binder is interposed between a cathode and an anode to form a cell. The cells are stacked through a separator and gas passages are formed on the cathode side and the anode side of each cell to form a fuel cell stack. Before operating the cell stack, an organic solvent is circulated into the gas passages of the stack 5 with a regenerating unit 21 to remove the binder. A judging unit 20 judges whether the binder is removed or not and the organic solvent is recovered in the regenerating unit 20 and the binder in the organic solvent is separated and the organic solvent is used again. By conducting organic solvent treatment at normal temperature, the binder is quickly removed without emitting an offensive smell, and judgement whether the solvent is removed or not is conducted at the same time.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for removing a binder from an electrolyte plate in a fuel cell used in the energy sector for directly converting the chemical energy of fuel into electrical energy. .

[Prior Art] Among the fuel cells that have been proposed to date, the molten carbonate type fuel cell is one in which molten carbonate is impregnated into a porous material as an electrolyte, as shown in an example in Fig. 3. Electrolytic trade temporary (TAINORE) 1 with a cathode (oxygen 4 drops)
It is sandwiched between both electrodes 2 and anode (fuel electrode) 3, and oxidizing gas OG is supplied to the cathode 2 side, and the anode 3
One cell C is one in which electricity is generated by the potential difference generated between the cathode 2 and anode 3 by supplying fuel gas FG to the side, and each cell C is stacked in multiple layers with a separator 4 in between. It is designed to be a fuel cell stack S.

In the fuel cell described above, in the case of the internal manifold type, it is possible to wet-seal between the peripheral parts of the electrolyte plate 1 and the hipparator 4, and a supply side and a discharge side of the oxidizing gas OG are attached to each peripheral part. Channel holes 5 and 6
A gas passage 9 on the cathode 2 side and a gas passage on the anode 3 side are provided with passage holes 7 and 8 on the supply side and discharge side of the fuel gas FG, respectively, and are formed by unevenness provided on both the front and back sides of each separator 4. Each gas is made to flow through the passage 10.

The electrolyte plate 1 used in the above fuel cell was initially manufactured using a pot press method in which a mixed powder of lithium aluminate (LiANO2) and carbonate was filled into a mold, heated in a vacuum, and then pressed or shaped under high pressure. It used to cost 1 yen, but because it is difficult to make it large and mass-produce it, in recent years it has been manufactured using a tape molding method.

As shown in FIG. 4, the method for producing an electrolyte plate using the above-mentioned tape or shaping method is as follows: First, a raw material powder 11 of lithium aluminate powder is mixed with an organic solvent 12 such as acetone, alcohol, MEK (methyl ethyl ketone), and a surfactant. The lithium aluminate is divided into primary particles by adding a separating agent 13 consisting of a lithium aluminate, pulverizing and mixing them with a pulverizer 14 such as a ball mill, and then dispersing the lithium aluminate to primary particles. A plasticizer 15 such as phthalic acid and a binder 16 such as polyvinyl butyral are added and mixed to form a slurry 17, and then this slurry 1
The electrolyte plate 1 is manufactured by forming the electrolyte plate 7 into a tape using a tape forming device 18 such as a doctor blade device, an extrusion molding device, or a calender roll device, and then baking it in a drying chamber 19.

The electrolyte plate 1 manufactured by the tape molding method described above is
Since it contains an organic substance called binder 16, it is necessary to perform a degreasing process to remove binder 16 from electrolyte plate 1 before battery operation. In other words, if the battery is operated with the binder 16 and the resulting carbon remaining on the electrolyte plate 1 without being removed, molten carbonate as the electrolyte may seep into the electrolyte plate 1. Not only is it impossible to use the battery as a result of the failure, but in particular, if the binder 16 remains in the wet seal area, the carbonate will no longer penetrate into the wet seal area and the sealing performance will be impaired. It is necessary to remove the binder 16 from the electrolyte plate 1. Conventionally, from the electrolyte plate 1 to the binder 16
As a method for removing the binder 16, after the battery is assembled, the binder 16 is removed by gradually raising the temperature and baking it.

[Problems to be Solved by the Invention] However, in the conventional binder removal method described above, the number of
It takes a long time to remove because it has to be baked for a long time of 100 hours, a considerable odor is generated during removal, and it is difficult to judge whether the removal has been completed (degreasing judgment). There were other problems.

Therefore, the present invention aims to make it possible to remove the binder in the electrolyte plate in a short time at room temperature without generating any bad odor, and to make it possible to easily determine the degreased state. It is.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a cell in which an electrolyte plate containing a binder used during manufacturing is sandwiched between cathode and anode electrodes from both sides, with a separator in between. Bonding in an electrolyte plate in a fuel cell in which the binder is removed from the electrolyte plate of each cell of the fuel cell stack, which is stacked on a decoy to form a fuel cell stack having gas passages on the cathode side and the annotate side of each cell. In the method for removing the electrolyte, an organic solvent is passed through each gas passage on the cathode side and the anode side of each cell of the fuel cell stack at room temperature before operation, and the organic solvent in the electrolyte plate is introduced into the organic solvent. A method for removing a binder from an electrolyte plate in a fuel cell, characterized in that the binder from the electrolyte plate is removed by eluting the binder.

[Function] When an organic solvent is passed through the fuel cell stack at room temperature, the binder in the electrolyte plate is eluted into the organic solvent, making it possible to easily remove the binder without producing a bad odor. can. Furthermore, the degreased state can be easily determined based on the amount of binder eluted from the organic solvent.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the process for carrying out the method of the present invention, and as shown in FIG. A fuel cell stack S has a structure in which gas passages 9 and 10 are formed on the cathode 2 side and the anode 3 side for each cell C by laminating them with a separator 4 interposed therebetween. The solvent 12 is passed through each of the gas passages 9, 1.
0 is used to distribute the battery at room temperature before battery operation,
The binder 16 is removed from the electrolyte plate 1 by eluting the deadening agent 16 in the electrolyte plate 1 into the organic solvent 12, and the binder 16 eluted into the organic solvent 12 is removed.
The amount of the organic solvent 12 used to remove the binder 16 from the electrolyte plate 1 is recovered by the regeneration unit 21. After that, the binder 16 is separated and recycled again for removal of the binder 16.

To be more specific, first, before cell operation, an organic material is introduced into each of the supply-side passage holes 5 and 7 (see Fig. 3) for oxidizing gas and combustion gas formed in the fuel cell stack S at room temperature. Solvent 12 is supplied at the same time. As a result, the organic solvent 12 passes through the gas passage 9 on the cathode 2 side and the gas passage 10 on the anode 3 side of each cell C, and is discharged from each discharge side passage hole 6, 8 (see Fig. 3). , At this time, as shown in Figure 2, organic solvent 1
2 passes through the cathode 2 and anode 3 and soaks into the electrolyte plate 1 while flowing through the gas passages 9 and 10, so that the binder 16 in the electrolyte plate 1 gradually dissolves into the organic solvent 12. As a result, the binder 16 is removed from the electrolyte plate 1. When the organic solvent 12 used to remove the binder 16 in this manner is discharged outside the fuel cell stack S, the organic solvent 12 is then subjected to a degreasing determination section 20 using, for example, a liquid chromatograph. binder 16
The completion of the removal work is determined by detecting the amount of organic solvent 12 or by checking the electrical conductivity of the organic solvent 12. In this case, the amount of binder 16 eluted is large at first, but it gradually decreases, so monitor it with a monitor, etc., and when the amount decreases and about 80 to 90% has been removed without causing any problems in battery operation. It ends with. Furthermore, until it is determined that the removal work is complete, the organic solvent 12 discharged outside the fuel cell stack S is recovered by the regeneration unit 21 and the binder 16 is separated, and the organic solvent 12 after the binder 16 has been separated and removed is The solvent 12 is supplied to the fuel cell stack S and recirculated to remove the binder 16.

In this case, the organic solvent 12 to be recycled does not have to have the binder 16 completely removed.

When the binder in the electrolyte plate 1 in the battery reaction section is removed by simultaneously flowing the organic solvent 12 into the gas passages 9 and 10, the binder in the electrolyte plate 1 gradually escapes even in the wet seal area at the periphery. I'm coming.

As described above, in the present invention, the binder in the electrolyte plate 1 is removed by dissolving it into the organic solvent 12 at room temperature without using heat in the step south before the battery is operated. The degreasing process can be carried out in a few hours without producing any bad odor like conventional methods, and the degreasing state can also be determined using an organic solvent 12
The amount of binder 16 dissolved therein can be detected by liquid chromatography, electrical conductivity, etc., so it can be easily carried out.

In the above embodiment, the organic solvent 12 is fed into the fuel cell stack S and discharged. However, for example, the entire stack may be immersed in a tank containing the organic solvent 12. It goes without saying that the binder 16 may be removed by flowing the fi solvent 12 in a natural flow manner, and that various other changes may be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the method for removing a binder from an electrolyte plate in a fuel cell of the present invention, an organic solvent is passed through the fuel cell stack at room temperature before cell operation, and the organic solvent is removed from the fuel cell stack at room temperature. organic}
Since the binder in the electrolyte plate is discharged into the container, the binder can be removed in a short time without producing a bad odor, and the degreasing state can also be determined using an organic solvent. It can be easily done from the binder dissolved in it, and has excellent effects such as:

[Brief explanation of drawings]

Figure 1 shows the bonds in the electrolyte plate in the fuel cell of the present invention.
FIG. 2 is a partially enlarged cross-sectional view of a fuel cell stack showing a state in which the binder is removed by the method of the present invention, and FIG. 3 is an example of a fuel cell. The N diagram shown in Figure 4 is an electrical connection made using a tape method.
It is a process diagram showing the manufacturing method of quality board. DESCRIPTION OF SYMBOLS 1... Electrolysis plate, 2... Cathode, 3... Anode, 9... Gas passage on the cathode side, 10... Gas passage on the anode side, 12... Organic solvent, 16...・Binder, 20... Degreasing determination section, 21... Regeneration section, C...
・Cell, S...Fuel cell stack.

Claims (1)

[Claims] (1) A fuel that has gas passages on the cathode side and the anode side of each cell, in which cells are stacked in multiple layers with a separator in between, in which an electrolyte plate containing the binder used during production is sandwiched between cathode and anode electrodes from both sides. In a method for removing a binder from an electrolyte plate in a fuel cell in which a binder is removed from an electrolyte plate in each cell of the fuel cell stack, the method includes removing a binder from a cathode side and an anode side of each cell of the fuel cell stack. The binder in the electrolyte plate is removed by flowing an organic solvent through each gas passage at room temperature before operation, and eluting the binder in the electrolyte plate into the organic solvent. A method for removing binder from an electrolyte plate in a fuel cell.