JPS6124162A - Electrolyte layer for fused carbonate type fuel cell - Google Patents

Abstract

PURPOSE:To obtain an electrolyte layer having strong mechanical strength, low internal resistance, and the degree of freedom against deformation by staking and combining a matrix type electrolyte-holding agent and paste type electrolyte- holding agents. CONSTITUTION:A matrix type electrolyte-holding agent 16 and paste type electrolyte-holding agents 17 are stacked and combined. For example, LiAlO2 powder is mixed with an organic binder to form a green tape, which is calcined to sinter LiAlO2 grains, and the skeleton of the matrix type electrolyte-holding agent 16 is formed. On the other hand, a green tape made by molding LiAlO2 powder is used for the paste type electrolyte-holding agent 17. Then, the paste type electrolyte-holding agents 17 are stacked and combined on the matrix type electrolyte-holding agent 16 like a sandwich to form the skeleton of a hybrid type electrolyte layer 8, and gaps of the LiAlO2 skeleton are filled with fused carbonate to form the ion-conductive hybrid type electrolyte layer 8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to an electrolyte layer for molten carbonate fuel applications.

[Conventional technology]

In general, this type of fuel cell is composed of the members shown in the configuration diagram of FIG. pipe (6)
It is equipped with (2) is a current collector plate of the fuel side electrode, and is provided with a through hole (3) for a gas flow path. Generally, a nickel-based metal is used and the thickness is 1 to 2 meters. (4) is a fuel-side electrode, which is a porous electrode made of a sintered body of nickel-based metal powder. (8) is called the electrolyte layer,
L j2 in a porous structure mainly composed of LiAlO2
COB is made of carbonate mixed with carbonate such as K2CO2. (9) is the oxidizer side electrode, and like the fuel side electrode, it has a porous structure. This oxidizer-side electrode may use a nickel sintered body or a NiO sintered body, but in any case, under the operating conditions of the battery, N1p (L
+ ). Q□ is a current collector plate for the oxide film side electrode, which is made of stainless steel and has the same structure as the current collector plate for the fuel side electrode.

(B) is a gas flow path plate on the oxidizing agent side, and is provided with an oxidizing gas inlet pipe (to) and an outlet pipe o4.

Here, the structure of the electrolyte layer (8) will be explained in more detail. Conventionally, there are two types of this electrolyte layer (8). The first is LiA, which forms the porous structure of the electrolyte layer.
10g particles were sintered at high temperature (1100°C) to form LiAl
This is called a matrix type in which an O2 sintered body skeleton is formed and later impregnated with carbonate electrolyte. Therefore, in this case, even if the carbonate that is the electrolyte melts during battery operation, the porous skeleton of LiAlO2 remains strong. On the other hand, the second type is called a paste type in which L4ATOz particles are not sintered but LiAlO2 powder is simply formed into a plate shape and impregnated with carbonate. In this case, as the name suggests, the electrolyte layer is in the form of a hard paste and easily deforms during battery operation.

Next, the operation of this type of molten carbonate fuel cell will be explained. A fuel cell is a device that directly converts the chemical energy of a fuel gas such as hydrogen and an oxidant gas such as air into electrical energy through an electrochemical reaction to obtain electric power. In order to carry out this electro-chemical reaction efficiently, porous materials are generally used. poles are used.

Fuel a! The reactions at the I electrode and the oxidizer side electrode are as follows.

Fuel electrode side H2+COB” H2O+CO2+2e
<1) Oxidizer side CO2+802 + 2e →Co
(2) On the fuel electrode side, as shown in equation (1), H2 in the fuel reacts with COa in the electrolyte, forming water and CO2.
and generate electrons.

These electrons are sent to an external load through the fuel side electrode, and then flow into the oxidant side electrode. At the oxidizing agent side electrode, CO2 is generated from the electrons, CO2B', and oxidizing agent 02, and is dissolved in the electrolyte, whereby a battery reaction progresses.

[Problem that the invention seeks to solve]

Conventional molten carbonate fuel cells are constructed as described above, and use a matrix type or paste type electrolyte layer. Although the matrix type has strong mechanical strength, it has a large internal resistance as an electrolyte layer, and when the electrode contracts, it simultaneously deforms and cannot absorb the contraction. Further, in the case of the paste type, the internal resistance is lower than that of the matrix type, and there is a degree of freedom for deformation, but there is a problem in that the mechanical strength is weak.

The present invention was made to solve these problems, and provides an electrolyte layer for molten carbonate fuel cells that has strong mechanical strength, low internal resistance, and a high degree of freedom in deformation. .

[Means for determining the point of view]

In this invention, the electrolyte layer for a molten carbonate fuel cell is a composite of a matrix type and a paste type electrolyte holding material stacked on top of each other.

Effect of means for solving problem C] The electrolyte layer of the present invention is a composite of matrix type and paste type t-solite retention materials, which compensate for the deficiencies of both, so that mechanical A product with high strength, low internal resistance, and flexibility in deformation can be obtained.

〔Example〕

An embodiment of this invention will be described below.

In C, a tape molding method using an organic binder, which is a method for manufacturing ceramic substrates that has been widely used in the field of electronic material technology in recent years, is used as a method for molding Li A 102 powder, which is a material for an electrolyte holding material.

First, a matrix type electrolyte holding material is prepared by mixing LiAlO2 powder with an organic binder and using a doctor blade to form a green tape with a thickness of 0.05 to 1cm. This was treated at about 1400°C and L 1A
The 102 particles are sintered to form the skeleton of the matrix type electrolyte holding material.

On the other hand, paste type electrolyte holding material is still LiA
0,06-1 made by molding lO2 powder by tape molding method
Use mIn green tape.

Next, the previously produced matrix type electrolyte holding material is laminated like a sandwich with a paste type green tape, ie, a paste type electrolyte holding material, to form a composite skeleton of hybrid electrolyte waste.

In contrast to the conventional type, the hybrid type electrolyte layer manufactured as described above has a structure in which matrix type electrolyte holding material QQ is sandwiched between paste type electrolyte holding materials αη as shown in the cross-sectional view of Figure 1. are doing. Such a hybrid type electrolyte layer (8) is fa
When incorporated into a battery as shown in Figure 4, the organic binder of the paste-type electrolyte holding material is removed when the battery operating temperature reaches 650°C, leaving the L1AIO2 skeleton. Attach carbonate, which is an electrolyte, from the outside and L
The voids in the iAlO2 skeleton are filled with molten carbonate to form a hybrid type electrolyte layer (8) having ionic conductivity.

The mechanical strength of the electrolyte (8) is reinforced by the matrix-type electrolyte retaining material QQ, and the paste-type lI# retaining material aV has a certain degree of softness, and as shown in Fig. ), (9) to supply electrolyte to the electrode.

In addition, in the above embodiment, a hybrid type electrolyte layer (8) having a three-layer structure was explained, but FIG.

A hybrid type electrolyte layer (8) having a two-layer or five-layer structure as shown in the block diagram of FIG. 8 is also considered. Further, even if the structure is expanded to a multilayer structure, the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the matrix type electrolyte holding material and the paste type electrolyte holding material are stacked together to form a composite material, which has strong mechanical strength, low internal resistance, and a degree of freedom in deformation. This has the effect of providing an electrolyte layer for a molten carbonate fuel cell.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an 8-layer electrolyte layer for a molten carbonate fuel cell according to an embodiment of the present invention, and FIGS. 2 and 8 are 2-layer and 5-layer electrolyte layers according to another embodiment of the present invention, respectively. FIG. 4 is a cross-sectional view showing the electrolyte layer of FIG. 4, and FIG. 4 is a configuration diagram showing a general molten carbonate fuel cell. (8) Electrolyte layer, a9 Matrix type electrolyte holding material, αη Paste type electrolyte holding material Note that in the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) An electrolyte layer for a molten carbonate fuel cell, which is a composite of a Mylix type electrolyte holding material and a paste type electrolytic holding material. (2) The electrolyte layer for a molten carbonate fuel cell according to claim 1, wherein the matrix type electrolyte holding material is obtained by molding ceramics, which is a raw material for the electrolyte holding material, into a plate shape and sintering it. (3) The electrolyte layer for a molten carbonate fuel cell according to claim 1, wherein the paste type electrolyte holding material is formed by molding ceramics, which is a raw material for the electrolyte holding material, without sintering.