JPH0734278A - High temperature steam electrolytic cell - Google Patents

Abstract

PURPOSE:To improve the airtightness of an electrolytic cell by adding SiO2 or MgO to oxide interconnectors which are used for joining unit electrolytic cells to each other in series while applying a pressure at a high temp. and joining the unit cells with the glass melt of the above oxide. CONSTITUTION:This high temp. steam electrolytic cell comprises the unit electrolytic cells and the oxide interconnectors 4 for joining the unit cells to each other in series. Each of the above unit electrolytic cells is provided with the cathode 3 on one surface of and the anode 2 on the other surface of the tubular oxygen ion conductive solid electrolyte 1. Further, SiO2 or MgO is added to the above interconnectors 4 and the unit electrolytic cells are joined with the glass melt of SiO2 or MgO and accordingly, the airtightness of the high temp. steam electrolytic cell can be improved.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to improvements in high temperature steam electrolysis cells.

[0002]

2. Description of the Related Art The operating principle of a high temperature steam electrolysis cell is shown in FIG. Oxygen ion conductive solid electrolyte 1 provided with electrodes 9
This solid electrolyte 1 was heated to a high temperature of 00 ° C to 1000 ° C.
As a partition wall, supply steam to one side and air to the other side,
When a voltage is applied between the electrodes by the external DC power supply 5 so that the water vapor side electrode (cathode) 3 has a negative potential, the water vapor is electrolyzed at the cathode 3 to generate oxygen gas and oxidizing gas. Of the generated gas, oxygen gas is oxygen-ionized and diffuses in the solid electrolyte 1, and electrons are emitted at the air-side electrode (anode) 2 to become oxygen gas. The remaining hydrogen gas is used as product hydrogen. In order to efficiently perform steam electrolysis using such a high temperature steam electrolysis cell, it is necessary to electrically connect the unit cells in series.

There are two modes of cell structure. One is called a cylindrical support structure, in which a porous tube is used as a support to form unit cells thereon, and each cell is connected in series by an interconnector. The other is a cylinder. This is called a type non-support structure, in which the unit cells themselves become a support structure and each cell is connected in series by an interconnector. When operating as a high temperature steam electrolysis cell, it is necessary that hydrogen gas does not leak to the outside, but the cylindrical support structure has sufficient airtightness for the electrolyte and interconnector formed on the support. Since it is difficult to make the structure, it is difficult to reduce the leakage of hydrogen gas from the cell and the interconnector itself.
On the other hand, since the cylindrical unsupported structure can be sufficiently densified before connecting the cell and the interconnector in series, if there is no leakage of hydrogen gas from the joint between the cell and the interconnector, It is possible to manufacture a series junction cell having excellent airtightness. For joining the cell and the interconnector, there is a method of joining the electrolyte tube and the interconnector tube under pressure at a high temperature, whereby a series cell structure having excellent airtightness can be produced.

[0004]

The features of the high temperature steam electrolysis cell are as described above. However, when the electrolysis cells are connected by high temperature pressure bonding, no gas leak should occur at the joint. The present invention is to provide a high temperature steam electrolysis cell capable of preventing gas leakage from a portion where the electrolysis cell and the interconnector are joined, in a high temperature steam electrolysis cell configured by connecting electrolysis cells through an interconnector by high temperature pressure joining. To do.

[0005]

The present invention is directed to a unit electrolytic cell having a cathode on one side and an anode on the other side of an oxygen ion conductive solid electrolyte tube, and an oxide intercalator for connecting the unit electrolytic cells in series. In a high temperature steam electrolysis cell consisting of a connector, SiO ₂ or Mg was added to the oxide interconnector.
A high-temperature steam electrolysis cell characterized in that O is added.

The oxide interface used in the present invention
LaCrO as the material of the connector ₃, La_0.8Ca
_0.2CrO₃, La_0.8Sr_0.2CrO₃, La_0.8M
g_0.2CrO₃And the like.
SiO added to the connector₂Or the amount of MgO added is
The range of 5 to 10 wt% is preferable respectively.

[0007]

In a high-temperature steam electrolysis cell in which an electrolysis cell and an interconnector are joined in series by high-temperature pressure joining, SiO ₂ or MgO is added to the interconnector material to bond the electrolysis cell and the interconnector to Si.
Since they are joined by a glass melt of O ₂ or MgO, an electrolytic cell having excellent airtightness is formed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a cross-sectional view of one embodiment of the high temperature steam electrolysis cell of the present invention. Solid electrolyte 1 is ZrO ₂ with 14 wt% of Y ₂ O ₃
Oxide powder obtained by mixing in air at 1800 ° C. for 10 hours and crushed to an average particle size of 1 μm or less, and molded into a cylindrical shape by a hydrostatic pressure device. , Further processed into a ring shape. The solid electrolyte ring has a diameter of about 20 mm and a wall thickness of 500 μm to 300 μm.
μm.

The anode 2 is an LaMnO ₃ oxide, and lanthanum oxide and manganese oxide are mixed so that La: Mn = 1: 1, and the mixture is baked in air at 1300 ° C. for 10 hours. It is formed by applying and baking the above. The cathode 3 is Ni / YSZ
It is made by baking cermet. In interconnector 4 LaCrO ₃ type oxide, lanthanum oxide, chromium oxide La: Cr = 1: 1 and were mixed so that, thereto to SiO ₂ or MgO was added, respectively 2~3wt% 1300 ℃ in air It was fired for 10 hours, pulverized to have an average particle size of 1 μm or less, molded into a cylindrical shape by a hydrostatic pressure device, and further processed into a ring shape.

The high temperature steam electrolysis cell of the present invention can be obtained by stacking a solid electrolyte ring and an interconnector ring and bonding them at a bonding pressure of 0.2 kgf / cm ² in air at 1300 ° C. to 1500 ° C. The relative density of the sintered body of LaCrO ₃ which is a conventional oxide interconnector was 64%, but the relative density of the interconnector of the present invention when SiO ₂ or MgO was added was 95%.

[0011]

As described above, according to the present invention, in the high temperature steam electrolysis cell, M is added to the oxide interconnector.
By mixing gO or SiO ₂ , it becomes easy to join the solid electrolyte and the interconnector tube, and it is possible to provide a high temperature steam electrolysis cell without gas leakage.

[Brief description of drawings]

FIG. 1 is a sectional view of a high temperature steam electrolysis cell according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the principle of a high temperature steam electrolysis cell.

Claims (1)

[Claims] 1. A high temperature steam electrolysis cell comprising a unit electrolysis cell having a cathode on one side and an anode on the other side of an oxygen ion conductive solid electrolyte tube, and an oxide interconnector for connecting the unit electrolysis cells in series. _2. A high-temperature steam electrolysis cell characterized in that SiO ₂ or MgO is added to the oxide interconnector.