JPS58155667A - Molten-carbonate fuel cell - Google Patents

Abstract

PURPOSE:To increase the mechanical strength and the electrolyte-holding ability of a molten-carbonate fuel cell, and prevent any cracks or deformations from being generated in the fuel cell by packing an electrolyte into the spaces of a self-supporting base body at least the surface layer of which consists of an alkali-proof non-conductive matter. CONSTITUTION:The surface of a metallic self-supporting base body is coated with an alkali-proof non-conductive matter. Then, the spaces of the self-supporting base body are packed with an alkali-proof non-conductive minute powder which is used as both an electrolyte and an electrolyte-holding member. In carrying out such a packing, either a method of immersing the base body in a homogeneous slurry prepared from the minute powder, or a method of pressing a paste prepared from the minuter powder into the base body is adopted. Here, it is preferred that the minute powder is packed as densely as possible. As a material for the self-supporting base body, ceramics is usually used, and an alkali-proof non-conductive member such as magnesia or lithium aluminate is preferred.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a molten carbonate fuel cell, and particularly to an electrolyte body containing an alkali carbonate electrolyte.

There are both matrix type and paste type electrolyte bodies.The former is an electrolyte body that holds electrolyte in a porous ceramic sintered body, and the latter is a molded mixture of electrolyte and alkali-resistant heat-resistant fine powder. It is an electrolyte body made of However, the electrolytic monolithic bodies of the prior art are not fully satisfactory in the following respects.

l) Occurrence of cracks during the manufacturing process.

2) Cracks occur due to thermal cycles during battery operation.

3) Thermal deformation as the battery operates (especially in paste-type electrolyte bodies).

An object of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a battery that has excellent mechanical strength, low electrolyte retention, no cracking or deformation, no crossover, and can exhibit high battery performance. An object of the present invention is to provide a molten carbonate fuel cell using a novel electrolyte body.

The gist of the present invention is to use an electrolyte body, in which an electrolyte is filled and held in the voids of a self-supporting substrate whose surface layer is non-conductive and made of an alkali-resistant material, as an electrolyte body for a molten carbonate fuel cell. It is.

More preferably, it is preferable to use an electrolyte body in which the electrolyte is retained in the presence of round alkali-resistant fine powder that retains the electrolyte in the voids of the self-supporting substrate.

The self-supporting substrate referred to herein is a structure whose skeleton is continuously connected and has voids, and typical examples thereof are a honeycomb-like structure and a three-dimensional network structure. The porosity is preferably 70% or more, so that the electrolyte can effectively play its role as an ion conductor.

The self-supporting substrate is usually made of ceramic material. For example, alkali-resistant and non-conductive materials such as magnesia and lithium aluminate are preferred. At least the surface layer of the base material is titania.

If it is converted to a substance stable against alkali carbonates such as zirconia, cordierite, or mullite, it can be used as a suitable self-supporting substrate.

Additionally, self-supporting substrates made of gold-14 can also be used as self-supporting substrates within the scope of the present invention. In this case, the surface layer is coated with an alkali-resistant and non-conductive substance, or at least the surface layer is coated with an alkali-resistant and non-conductive substance.

A typical example is a substrate in which the self-supporting substrate is substantially made of aluminum, and at least the surface layer of the substrate is oxidized to convert into alumina, and more preferably, this substrate is treated with lithium to form lithium aluminate. There is a method using a converted substrate.

It is also possible to use a non-conductive material such as chromium oxide (CrtOn) by coating the surface layer of the self-supporting metal substrate.

A feature of the present invention is that it utilizes an excellent mechanical fill of a self-supporting base, and the self-supporting base plays a role as a core material of the body, The generation of cracks due to heating cycles or during battery operation can be almost completely eliminated, and no thermal deformation is observed.

Another feature of the present invention is that by filling the voids of the self-supporting substrate with alkali-resistant and non-conductive fine powder, the electrolyte retention ability is significantly improved, and therefore the bubble withstand voltage is increased. The cross-over phenomenon can be prevented, and the abnormal outflow of electrolyte to the electrodes and other components can be suppressed, so that stable battery performance can be maintained.

Methods for filling the voids of the self-supporting substrate with alkali-resistant, non-conductive fine powder, which is an electrolyte and electrolyte holding material, include impregnation and immersion as a slurry of fine powder t-q, and press-fitting in the form of a paste. However, it is preferable that the fine powder be packed as densely as possible.

It is also possible to sinter the fine powder after charging #74.

The electrolyte holding body thus obtained is melted and impregnated with an alkali carbonate as an electrolyte to obtain an electrolyte body.

Another method is to simultaneously impregnate alkali-resistant, non-conductive fine powder and electrolyte in a mixed state.

The content of alkali carbonate is preferably 40 to 70% by weight.

Hereinafter, the content of the present invention will be explained in more detail with reference to Examples.

Example 1 An aluminum/lithium oxide honeycomb structure with a mesh opening of 3 m + wall thickness of 0.5 ws + square openings was heated to 100 wX
A self-supporting substrate was cut out into a shape of 100 cm x 2 m thick.

Mixed carbon of 5Qwt% lithium aluminate, lithium carbonate and potassium carbonate with an average particle size of 1 μm as an electrolyte holding material #
R salt (62:38, molar ratio) t-11 An electrolyte body material containing 50% by weight of solute was added with water to form a paste, and this was press-fitted into the above self-supporting substrate. After drying for 2 hours at 530 C (06
Melt and immerse the above mixed carbonate in this at a temperature of 4°C to form an electrolyte body.
fc.

32 g of electrolyte material was held in the voids of this self-supporting substrate.

Example 2 An aluminum sleeve three-dimensional network structure having a shape of 100 sam x 1001 a I x thickness 2 cm and an average pore diameter of z 5 cm was
After oxidation treatment at a temperature of 0C for 5 hours, it was treated with lithium hydroxide at 450C for 24 hours to obtain a self-supporting substrate.

In the same manner as in Example 1, a '-lyte material was filled and held in the voids thereof to obtain an electrolyte body.

39g of electrolyte material was held in the void of this self-supporting substrate.Example 3 Example 1. A rate cell was constructed using the Marugame solute obtained in Example 2, and battery disease was measured.

A porous nickel sintered plate is used as an anode, and the lithiated nickel oxide sintered plate is used as a cathode.A mixed gas of 50% HtN is applied to the anode side, and a 15% HtN gas is applied to the cathode 1411. -30% Co, -N, and mixed gas were supplied. As a result of measuring the cell voltage at a discharge current density of 100 mA/m'' at 650C, 0.76 V was obtained for the former, 0.79 V for the latter, and after 100 hours K>I-' (also 0.77 V, respectively). It was 0.80V.

Claims (1)

[Scope of Claims] 1. An electrolyte body containing an electrolyte disposed between an anode and a cathode, and a fuel chamber and a cathode side in which a fuel and an oxidizing agent are respectively disposed on the anode side. By supplying the electrolyte to an oxidizer chamber arranged in A molten carbonate fuel cell characterized by using an electrolyte body made of 2. In the fuel cell according to claim 1, the voids of a self-supporting substrate at least the surface layer of which is non-conductive and made of an alkali-resistant material are filled with fine powder, which is an electrolyte holding material. A molten carbonate fuel cell characterized by using an electrolyte body. & A molten carbonate-based fuel cell according to claim 1 or 2, wherein the self-supporting substrate is a ceramic honeycomb-like structure or a three-dimensional network structure. . 4% allowance#'! Item 1 In the fuel cell according to item 1 or item 2, the self-supporting substrate is a honeycomb-like structure or a three-dimensional network structure made of gold, at least the surface layer of which is non-conductive and alkali-resistant. A molten carbonate fuel cell characterized in that it is converted into or deposited with a nine-substrate structure. 5. In the fuel cell according to claim 4, the honeycomb structure or the three-dimensional mesh structure is substantially made of aluminum, and at least the surface layer thereof is converted to lithium aluminate. A molten carbonate fuel cell characterized by: