DE1596321B1 - HIGH TEMPERATURE FUEL ELEMENT WITH OXYGEN ION CONDUCTING SOLID ELECTROLYTE - Google Patents

Description

3 4

A b b. 3 shows a diagram of discharge curves of sulfate CuSO ₄ · 5 H ₈ O, 6.16 g of magnesium sulfate, similarly opposed oxygen electrodes MgSO ₄ · 7H ₂ O, 23.7 g of aluminum potassium sulfate
and

A b b. 4 shows a diagram of the discharge curve of the er ^K 2 ^A ls (SO ₄ ) ₄ · 24H ₂ O

fuel element according to the invention in comparison 5 dissolved in 1 liter of water and then with about 1 mol with conventional elements. diluted ammonia solution neutralized. That so

The fuel element according to A b b. 1 points to the hydroxide obtained is washed out in water, a fuel 10O ⁰ C is dried on one side of a solid electrolyte 3 and then at 1050 ⁰ C about electrode 1 and on the other side an oxygen 10 hours in air. The X-ray analysis shows electrode 2. The element constructed in this way is under io that the metal oxides produced in this way form various forms of a fuel-gas space 5 and an acidic solution and have spinel crystal structure material-gas space 6 in a housing 4 made of heat.

permanent insulating material used. The fuel will apply to the manufacture of an oxygen electrode

• fed through the inlet opening 7 of the housing 4, the following example: Five metal oxides, ζ. B. Manganese and he leaves this as exhaust gas through the outlet 15 dioxide, nickel oxide, cobalt oxide, aluminum oxide and opening 8, after he is mixed with the fuel electrode 1 magnesium oxide are molar equivalent. Has been brought to a reaction. The oxygen is, for example, 6.3 g of manganese nitrate Mn (NO ₃ ) ₂ · • are fed in through opening 9 and the exhaust gases are discharged at 10 4H ₂ O, 6.55 g of nickel sulfate NiSO ₄ · 6H ₂ O, 7.03 g of Ko. The negative pole 11 and the positive pole 12, balt sulfate CoSO ₄ -7H ₂ O, 6.16 g magnesium sulfate both made of Pt, are on the front of the housing 4 20 MgSO ₄ · 7H ₂ O, 23.7 g aluminum potassium sulfate
arranged. The fuel electrode 1 and / or the

Oxygen electrode 2 can be made from a fine powder of their K-2Al ₂ (bO ₄ ) ₄ · 24H ₂ O

Mixture portions be sintered. dissolved in 1 liter of water and then with about 1 mol

The redox effect is neutralized within a very dilute ammonia solution. The little Fluctuation range at high speed 25 Hydroxide recovered is washed out in water at dried on the fuel electrode as well as at 100 ° C and then at 1050 ° C the oxygen electrode. This takes place with the Sauer- 10 hours heated in air. The X-ray analysis shows A solid phase reaction takes place on the material carrier. The acid - that the prepared oxides as in the case of the fuel electrode is practically stepwise between electrodes are solid solutions and spinel crystals have a higher oxidation level and a low structure.

The solid electrolyte is oxidized in a known manner.

Spinel structure of the electrode is impaired by the fact that zirconium dioxide ZrO ₂ and Kaierfahrt, zium oxide CaO ₂ in a molar ratio of 0.85: 0.15

The redox mechanism of the fuel and that are mixed, the mixture is then pulverized, ge-oxygen electrode is subsequently stirred by means of 35, through a sieve with the sieve no. 0.08 explained according to electrochemical reaction equations. The DIN 1171 is passed, then under a pressure process on the fuel electrode is followed by about 1 t / cm ² pressed and finally about as follows: 10 hours at 1500 ° C is sintered.

Using the electrodes thus obtained

MO »+ fuel ^ -MO _n _» + oxidized product 40 a fuel element according to Fig. 1 was produced

(1) and the following experiments on the discharge characteristics were carried out, whereby the properties of the MO _n -X + xO * - -> M0n + 2xe- (2) fuel electrode of the element were tested.

On the oxygen electrode: 45 example

M'Om + - x · O ₂ ->M'Om + x (3) The fine powder of the solid electrolyte became to

2 formed a plate approximately 1 mm thick

, _n _,. . one surface of which a paste has been applied,

U M _{m + X} + ZXQ - + MO _7n + x · O ifi) _{50, by kneading the} f _a pavers of metal oxides

for use in the fuel electrode with

This gives the total sales: Ethyl alcohol was prepared. On the other side

2, a paste was applied, which by kneading

Fuel H χ · O ₂ -> oxidized product (5) of fine platinum black powder for use

2 55 obtained in the oxygen electrode with ethyl alcohol

became. Then at 135O ⁰ C about 2 hours

In the reaction equations, MO means »and sinters. The electrodes were approximately 1 mm thick. M'Om a metal oxide of the fuel or oxygen to the electrode, a platinum wire was used as a guide wire electrode. for measuring the electrical current and the voltage Below, the Her- 60 is soldered on using an example. The reaction area of the electrode was explained in the position of the fuel electrode. Seven divided 3.2 cm ² , and the overall structure of the element decided metal oxides, namely manganese dioxide, zinc spoke to the one in A b b. 1 reproduced. Propane was mixed as fuel oxide, chromium oxide, iron oxide, copper oxide, and magnesium, and oxygen and aluminum oxide were mixed in as oxygen carriers, molar equivalents being fed in at a low flow rate of 100 ml / min. For example, 6.37 g of manganese nitrate 65 In the A b b. 2 to 4 is the discharge voltage (V) Mn (NOg) ₂ · 4H ₂ O, 7.19 g of zinc sulfate ZnSO ₄ · 7H ₂ O, on the ordinate and the current density (mA / cm ² ) on 20.0 g of chromium nitrate Cr (NO ₃ ) ₃ · 9H ₂ O, 19.6 g iron - plotted on the abscissa. At the moment of the ammonium sulfate FeSO ₄ (NH ₄ ) ₂ · SO ₄ · 6H ₂ O, 6.24 g copper operation of the element according to the invention at 1000 ° C

5 6

Characteristic curve obtained from working oil temperature Example 3

is in A b b. 2 denoted by A. At one temperature

⁰ of 91o C results in the curve B. A further experiment was preferred with the

The fuel element of conventional design, wel- embodiment of the fuel according to the invention carried out in the same way as the inventive by 5 element, with metal oxide-catalysis combination of the listed solid electrolyte goals for both the fuel and for the acid with the fuel and oxygen electrodes - cloth electrodes have been used. This fuel Placed has been wherein for both the known fine element was used in cell temperatures of 1010 and platinum black powder, was operated at 890 ⁰ C, and there were thereby the curves lines temperatures of 1010 and 916 ⁰ C operated. io G or Hin A b b. 4. The conventional used here The results obtained show the curves C and the element was the same as in Example 1, for which D. As can be seen, the performance of the invention, the curves C and D apply.

appropriate element in both cases above that of the A b b. 4 is the superiority of the burning

convenient element. Fabric element according to the invention compared to the

The properties of the oxygen electrode of the conventional element can be seen, and from the fuel element according to the invention were as Ab b. 2 and 3 result in the excellent self-following examined: shafts of the fuel or oxygen electrode.

_B. -ίο * - ** ^e combination of a solid electrolyte with a

^eI P ^e electrode made of metal oxides shows that the

The fuel element according to the invention was 20 sintering the adhesiveness between the elec-

in the same way as according to Example 1 under Verode and the solid electrolyte is much stronger

Use of metal oxides as oxygen electrodes than with mere accumulation, so that not only the me-

and fine platinum black powder as fuel electrical strength, but also conductivity

trode manufactured. This item was at 1020 and is being improved. The fuel element doesn't just do

89O ⁰ C operated, whereby the curves E and F in 25 expensive metals are unnecessary and enables the

A b b. 3 result. The element of conventional design twist of relatively cheap metal oxides, rather

"was the same as in Example 1, it resulted in the curves it is also easy to handle and handle

C and D. sits a compact design.

1 sheet of drawings

Claims (1)

1 2 be subjected to a heat treatment. The patent claim: however, the service life of such elements is short. The endeavor continues to focus on creating a To develop a fuel element with an oxygen ion substance element, the electrodes of which are simple conductive solid electrolytes for operation at high 5 and cheap to manufacture and their lei temperatures, Characterization capability is improved by the fact that the fuel electrode is spinel from a surface deposits on the electrodes be avoided with equimolar amounts of manganese. dioxide, zinc oxide, chromium oxide, iron oxide, copper According to the invention, these advantages are in a oxide, magnesium oxide and aluminum oxide and the io fuel element with a conductive oxygen ion Oxygen electrode made from a spinel with equi-solid electrolyte for high-temperature operation thereby molar amounts of manganese dioxide, nickel oxide, achieved that the fuel electrode consists of a Cobalt oxide, aluminum oxide and magnesium oxide spinel with equimolar amounts of manganese dioxide, consists. Zinc oxide, chromium oxide, iron oxide, copper oxide, magnesium oxide and aluminum oxide and the oxygen electrode from a spinel with equimolar amounts of manganese dioxide, nickel oxide, cobalt oxide, aluminum The invention is directed to a fuel element consisting of nium oxide and magnesium oxide, with an oxygen ion-conducting solid electrolyte The electrodes of the fuel according to the invention for operation at high temperatures. 20 elements are extremely easy to manufacture, if The use of solid fuels in fuel is believed to be made by sintering fine elements requiring the use of high workstem powders. Their mechanical strength temperatures ahead, in which melt flow electrolytes and the resulting service life can be used accordingly. There are, however, not great, and they may face sufficiently contradictory 25 working temperature between about 400 and 1000 ⁰ C lofted materials available to the optimal ranges of these alkali melts. For this to be used. The reason has been to cells with solid electrolytes. The particular suitability of the mixtures for starting, which are more compact and easier to handle to form the fuel electrode and oxygen electrode are'. Commonly used are fuel electrodes, at least in part it can be assumed that electrodes made of a single metal such as Pt, Ni, Fe 30 that the metals used have different valence or the like, which can primarily accept in reaction with hydrogen. As a result, those are displaced from the will. Apart from the comparatively different metal oxides composed of electrical rings Activity of this fuel electrode is also easily oxidizable and reducible, so that the electrodes a hydrogen decomposition takes place. On the other hand; store electrodes form a redox system. In connection 35 on the surface of the fuel electrodes with a corresponding fuel, such as. B. impurities, which the electrolyte quickly become unusable do. The use of carbon- thane, ethane, propane as reducing agents on pages Hydrogen as a fuel is considered by its propensity of the fuel electrode and air to be oxygen impaired to polymerization. Oxidizing agent on the side of the oxygen electrode In the case of fuel elements with solid electrolyte 40 and taking into account the fact that the If the oxygen electrode is mainly made of platinum, metal oxides act as catalysts, the leads its effectiveness in the same way as the fuel from a catalytically influenced reaction, the fuel electrode from the Adsorptiohsreäktion in which it shows a largely ideal characteristic, depends on the surface. Therefore the electrolyte oxidized with die by electrochemical reaction is this Cell achievable current density limited. In addition 45 trode comes into contact with the fuel and comes that platinum is immediately afterwards damaged by a catalytic purification, even with the slightest gas pollution reacts, * thus reducing the catalytic reaction action. The ability of the electrode to self is affected. to cause a redox cycle without z. B. A well-known fuel element with solid electro- carbon is split off, prevents the ablytes, the electrodes, made of porous, gas-permeable 50 storage of impurities on the electrode ferrite material has, assumes. that the surface. Oxygen electrode not at operating temperature The spinel structure of the fuel electrode and can be further oxidized and that the fuel-oxygen electrode is decisive for the development Electrode itself if possible through reducing gases in the redox system, whereby the X-ray analysis is more practical Glowing heat little, can be influenced. As a result, there is no difference in the table as to whether this is possible the fuel electrode must not contain any oxides from the alkali redox system now in the reduction or in the oxide and alkaline earth metals as well as volatile oxides tion stage. As a result of their increased mecha included. Achieving a strength in a very narrow niche is the electrode through the redox range lying porosity of an electrode is not exposed to excessive load, really difficult. This fuel consists of 60 Further details can be found in the following element also the risk of decomposition of the oxidati- Description of a preferred embodiment of the onsmittel and the impairment of the porosity of the fuel element as well as on the basis of the drawing. Oxygen electrode through reaction residues. Here shows Another known fuel element with a fixed A b b. 1 shows a schematic longitudinal section through Electrolyte uses a fuel element as the fuel electrode of a 65 Mixture of iron oxide, iron filings and alumina A b b. FIG. 2 is a diagram of the discharge curve of FIG as well as an oxygen electrode of a mixture of comparatively contrasted fuel electro iron oxide, magnetic oxides and alumina, which