DE1596078B1 - CATIONICALLY CONDUCTIVE CRYSTALLINE SOLID ELECTROLYTE MADE FROM A MIXED CRYSTAL LATTICE AND CATIONS THAT MOVE WITHIN THE CRYSTAL LATTICE UNDER THE INFLUENCE OF AN ELECTRIC FIELD AND THEIR APPLICATION AND PRODUCTION - Google Patents

Description

The invention relates to new cation-conducting crystalline multi-metal oxides and their use. Particularly these solid electrolytes according to the invention for the cationic connection between the aniodic and cathodic reaction zones are used. They are practically impermeable to the liquid Reactants used in the devices when the reactants are in elemental or anionic form or compound form are present:

Fundamental to the invention is a new solid electrolyte and its usability in a large one Variety of energy conversion devices.

The cationically conductive, crystalline solid electrolyte according to the invention consists of a mixed crystal lattice and cations which migrate with respect to the crystal lattice under the influence of an electric field, wherein the crystal lattice essentially consists for the greater part of ions of aluminum and oxygen and to a lesser extent consists of ions of a metal with a valence not greater than 2 and cations which migrate under the influence of an electric field.

Examples of these cations are cations of alkali metals, the preferred embodiment being consists of sodium ions. Examples of metals for a valency not greater than 2 are magnesium, Lithium, zinc, nickel and cobalt. Of these, magnesium and lithium are of fundamental importance.

The inventive method for Har-position The crystalline electrolyte consists of a greater proportion by weight of aluminum oxide and a Remainder from a larger part by weight of sodium oxide and a smaller part by weight of one Oxide of a metal having a valence not greater than 2 are thoroughly mixed, the resulting mixture is heated to crystal formation temperature, the resulting crystals to the desired shape and Size are compressed and the compacts are sintered.

In special applications of the invention there are primary batteries in which electrochemically reactive Oxidizing agents and reducing agents are applied and supported by a solid electrolyte are separated according to the invention, with which they are in contact, furthermore secondary batteries, in which are molten, electrochemically reversibly reactive oxidizing agents and reducing agents are separated by a solid electrolyte according to the invention with which they are in contact, furthermore thermoelectric generators, in which there is a temperature and pressure difference between anodic and cathodic reaction zones and / or maintained between the anode and cathode and in which a molten alkali metal is transferred in ionic form into the anodic reaction zone is, as a result of which electrons are given up to an external circuit, the ion form through the polycrystalline wall or inorganic membrane of the solid electrolyte according to the invention out and into the elementary form in the cathodic reaction zone after the absorption of electrons is converted back from the external circuit, as well as thermally regenerated fuel cells, in which a solid electrolyte according to the invention is used, or devices for separation or deposition of a liquid metal from one

liquid salt thereof, this material being electrofiltered by a solid electrolyte according to the invention will.

It goes without saying that when using the multi-metal oxide as a selective cation conveying device, as described in detail below with reference to a large number of energy transmission devices is explained, the migrating ion of the multi-metal oxide by the thereby to be transferred Cations is replaced. In the cells described below, the multi-metal oxide cell separator results an effective barrier to nonionic mass transport of the reactants for anions of liquid electrolyte reactants in embodiments employing such Electrolytes and for electron flow. In preferred embodiments it is practically opposite too Helium impermeable to 25 ° C.

Solid electrolytes and their use in energy conversion devices for generating electrical energy are known. It will do this for example referred to Galvanic Cells With Solid Elektrolytes Involving Ionic and Electronic Conduction, C. W a g η e r, Department of Metallurgy, Massachusetts Institute of Technology, pp. 361 to 377, in International Committee of Electrochemical Thermodynamics and Kinetics, Proceedings of the Seventh Meeting at Lindau, 1955, Butterworth Scientific Publications, London, England, 1957, and Solid Electroyte Fuel Cells, J. Weissbart and R. Ruka, Fuel Cells, C. J. Yοu η g, Editor, Reinhold Publishing Corporation, New York, New York, 1963.

It is an object of the invention to provide improved solid cationic conductive barriers which have a low electrical resistance and high resistance to chemical attack by alkali metals demonstrate.

The invention is explained in detail below in connection with the drawings, wherein F i g. 1 the use of an ionically conductive multi-metal oxide as a barrier layer and solid electrolyte in a simple accumulator battery cell with the anode of a liquid reactant and a cathode in contact with a liquid reactant as an electrolyte,

F i g. 2 the use of an ionically conductive multi-metal oxide in a primary battery, d. H. a thermoelectric Generator in which heat is converted into electrical energy using a pressure difference is transferred between the anodic and cathodic sides of the multi-metal oxide separation layer,

F i g. 3 shows the use of an ionically conductive multi-metal oxide in a further embodiment a primary battery, d. H. a thermally regenerated fuel cell,

F i g. 4 is a graph showing the electrical resistance properties of a multi-metal oxide which is prepared according to a preferred embodiment of the invention, depending on the Temperature,

F i g. 5 shows a test cell with discharge and charge circuits which is used to record the change in cell resistance over time while a crystalline multi-metal oxide according to the invention is used as an ionically conductive barrier against the mass transport of the liquid reactants, and
F i g. 6 graphically shows the changes in cell resistance

Show progress over time when using a multi-metal oxide according to the invention and a comparative sample.

The cationic conductive crystalline solid electrolyte of the present invention has a crystalline structure which essentially from a larger proportion by weight of ions of aluminum and oxygen and a smaller weight fraction of ions of a metal with a valence not above 2 in Crystal lattice bond and from cations, which with respect to the crystal lattice under the influence of an electrical Hiking in the field. These cations are preferably alkali cations, while as metals with a valence not greater than 2, particularly lithium and magnesium are preferred.

A preferred cationically conductive crystalline solid electrolyte is formed from a larger proportion by weight of aluminum oxide and a remainder, which consists essentially of a larger proportion of sodium oxide and a smaller proportion of the Oxide of a metal with a valence no greater. than 2, with the main aluminum component is in excess of about 80 percent by weight of the electrolyte and the remainder is the weight ratio from sodium oxide to the oxide of a metal with a valence not higher than 2 at least 2: 1.

In preferred embodiments of the solid crystalline electrolyte, the crystalline structure is made a major amount by weight of aluminum oxide and a remainder consisting essentially of a proportion by weight Consists of sodium oxide and a smaller proportion by weight of magnesium oxide or lithium oxide, formed by co-heating to the crystal formation temperature, the aluminum oxide an amount of more than 80 percent by weight, especially more than 85 percent by weight, of the structure, the sodium oxide more than 60 percent by weight of the remainder; and the magnesium oxide or lithium oxide make up more than about 1 percent by weight, in particular 1 to 4 percent by weight, of the remainder.

Solid electrolytes, which in their crystalline structure at least contain about 85 percent by weight aluminum oxide and the remainder magnesium oxide or lithium oxide is in an amount between about 1.5 and about 3.5 weight percent of the remainder.

The invention also results in very favorable applications for thermally regenerated Primary batteries, which have an anode container with a first molten metal inside the container, a cathode container with a second molten metal that is electrochemically molten with the first Metal is reactive and thermally separable from the first molten metal, in the cathode container, a regeneration unit located at a distance from the anode container and cathode container with heating device and a liquid separation system, outlet devices from the cathode container, Fluid connections to the fluid separation system and inlet facilities to the Anode container in fluid communication with the fluid separation system and the solid electrolyte as a half-cell barrier between the first molten metal and the second molten metal Metal and in fluid connections with it. The alkali metal is preferably made here from sodium and the second molten metal from tin.

The invention also results in a very favorable application for an electrochemical process for separating an alkali metal from a molten salt thereof, the anions of which are electrochemically are reversibly reactive with the cations of the metal, with the molten salt in contact with the solid electrolyte, which forms a half-cell separating layer that is impermeable to the metal, the salt and the anions and is selectively conductive with regard to the cations of the metal, is brought into contact and an electrical potential difference between the side of the separating layer, which is in contact with the salt and the opposite side with such a polarity switch is established that a flow of the cations of the metal from the salt through the separating layer in a single direction is caused.

The cationically conductive crystalline solid electrolytes according to the invention can be prepared in that intimately finely divided particles of aluminum oxide and oxides of a metal with a valence not greater than 2 are thoroughly mixed, the mixture obtained is pressed and the pressed body obtained is sintered at crystal formation temperature, the aluminum oxide represents the majority of the mixture, preferably more than about 80 percent by weight, and the remainder thereof consists of a minor proportion by weight of ions of a metal with a valence not higher than 2. Preferably, the alumina forms more than about 80 percent by weight of the compact and the remainder consists of sodium oxide with another oxide of a metal having a valence not greater than 2, the ratio of sodium oxide to the further oxide being at least 2: 1. Other possible oxides are, in particular, magnesium oxide and lithium oxide. The metal with a valency not greater than 2 forms more than 1 percent by weight of the remainder, preferably 1 to 4 percent by weight of the pressed body. Pressures above 70 kg / cm ² , preferably above 700 kg / cm ² , are used for pressing. It is particularly favorable to a method in which it is at a pressure in excess of 7,000 kg / cm ² compressed, and the compact is then sintered at a temperature higher than 1700 ⁰ C, in particular, when a metal having a valence not greater than 2 magnesium or lithium be used. Weight ratios of the compact of more than 85 percent by weight of aluminum oxide and of the oxide of the metal with a valency not above 2 of about 1 to 4 percent by weight of the compact are particularly favorable.

The invention is further illustrated below with reference to preferred examples.

example 1

According to FIG. 1 is a single cell secondary battery composed of glass tubes 11 and 31 and a disk of the crystalline Trimetal oxide 21 built up, which separates the tubes 11 and 31 and is liquid-tight on these is attached by means of glass seals 13 and 33. The tubes 11 and 31 have an inner diameter of about 12 mm. These and the glass seals 13 and 33 are made of a glass with an expansion coefficient corresponding to that of beta-aluminum oxide, for example Corning 7052, Kovar, ge

manufactures. The tube 11 is partially filled with molten sodium 15 and the tube 31 is filled with a molten sodium and sulfur containing reactant 35, for example sodium pentasulfide (Na ₂ S ₅ ). Sodium and Na ₂ S ₅ are kept in a molten state by conventional heating devices, not shown. The air in the tubes 11 and 31 can essentially be evacuated and the tubes closed or the cell can be operated in an inert atmosphere, for example argon. The plate 21 is about 12 mm in diameter and about 2 mm thick, the area exposed to the reactants in each of the tubes 11 and 31 being about 1.13 cm ² , assuming a completely smooth surface. All areas listed below are determined on this basis, which can be referred to as a geometric area.

In this cell, the molten sodium serves as both an anodic reactant and Electrode, while the sodium- and sulfur-containing reactant as both cathodic reactant as well as serving as a liquid electrolyte in contact with the electrode 19. Usually one starts the reaction when the cathodic reactant has a ratio of sodium too Sulfur of about 2: 5, and terminates the cell discharge when this ratio is at least about 2: 3. A copper wire line 17 extends into the

Sodium electrode 15, and an electrode 19 made of rust-30 to the external circuit goes through insulation free steel extends into the sodium pentasulfide 131, which extends through the top plate 109, and

between the plate 113 and the tube 111. The lower edge of the plate 113 is with a thin conductive Layer of a platinum paint 117, for example a platinum chloride in an organic reducing agent, provided, which is shown in FIG. 2 disproportionately strong in relation to the other components Relief of its portrayal is shown. In practice, this platinum layer is porous enough to allow it Sodium vapor can pass through it, and is strong enough and cohesive to keep the electricity flowing conduct.

The pipe 101 is equipped with an outlet line 119 with a valve 121. One not shown Vacuum pump is connected to line 119 to reduce the pressure in pipe 101.

The pipe 101 is further provided with a heating element 123 and an outlet line 125 with valve 127 for Removal of liquid from the tube 101 connected.

An inlet line 129 and the valve 131 provide the means for introducing a liquid in the pipe 111.

Tube 111 is partially filled with molten sodium 133.

A negative conductor 135 of copper wire to an external circuit, not shown, extends therethrough an insulation 135 and in the molten sodium 133. The insulation 137 extends through the top plate 109. A positive conductor 139 made of copper wire

35, which illustrate examples of terminals of an external circuit, which is not further shown, which a May contain a voltmeter, an ammeter and the like. The sodium is found in the discharge semicircle of this cell to the sulfur opposite the crystalline membrane (solid electrolyte according to the invention) attracted, releases an electron, passes through the membrane as a sodium ion and combines with a sulfide ion, which was formed at the cathode 19 while receiving an electron, whereby an electrical Current begins to flow through the external circuit listed above. The recharge is made by applying an external source of an electric current to the circuit using causes a reverse electron flow with respect to that of the discharge semicircle.

Example 2

In Fig. 2 of the drawing is a vessel 101 made of stainless steel, for example 2.5 cm inside diameter and 11 inches in length. The tube 101 has a flange 103 at its open end. Of the Flange 103 is provided with a notch or channel 105 in which a rubber O-ring 107 rests, the a vacuum-tight seal results when the cover plate 109 made of stainless steel on the tube 101 by means of a screw, bolt or other conventional fastening device, not shown, attached will. Inside the tube 101 and attached to the cover plate 109 is a smaller one Tube 111, for example about 12.7 mm inside diameter and 15.2 cm long. The lower end of the Tube 111 is through an annular plate of the crystalline trimetal oxide according to the invention 113 locked. Vacuum-tight glass seals 115 are provided for fastening the plate 113 to the pipe 111 and prevent passage of liquid in electrical communication with the platinum film 117. In an alternative form, conductor 135 may be connected directly to tube 111 if that Tube 111 consists of a good conductor.

When this cell is operated, heat is converted directly into electrical energy. The tube 111 is evacuated by pumping means through line 121 to a pressure lower than about 0.1 mm Hg and then sealed. The sodium 133 in the tube 111 is heated to a temperature of 300 ° C or higher, while the lower end of the tube is maintained at about 100 ⁰ C by the surrounding room temperature for one hundred and first The difference in the sodium vapor pressure on the two sides of the plate 113 results in the formation of an electrical potential difference across the plate. When electrons flow through the external circuit, the sodium 133 passes through the plate 113 in the form of sodium ions, which pick up an electron from the platinum electrode 117 and return to the elementary form.

Since the lower part of the tube is maintained at the relatively low temperature of about 100 ⁰ C 101, the sodium condensed there, and the pressure in the outer tube 101 provides the vapor pressure of sodium at about 100 ° C is represented by a possible pressure drop , which is already generated by the flow of sodium vapor from the platinum 117 to the cooler walls of the tube 101, is modified.

One advantage of this thermoelectric generator is that the hot and cold parts are too practical Any distance can be separated, reducing the influence of heat conduction losses between the hot and cold parts is kept to a minimum. With continuous operation that will condensed sodium in the bottom of tube 101 is heated and returned to the hot zone in tube 111.

Example 3

In Fig. 3, a vessel 201 which contains molten tin 203 is shown in sectional view. In the molten tin 203 extends a smaller vessel 205, also shown in section, the lower end of which is closed with a crystalline trimetal oxide plate according to the invention 207 and a glass seal, not shown. During operation, the vessels 201 and 205 are closed at their upper ends and / or covered with an inert gas. The vessel 205 contains molten sodium 209. The conductor 211 consists of a negative conductor to an external circuit, not further shown, and extends into the molten sodium, while the conductor 213 as a positive lead extends into the molten tin.

The vessel 201 is in fluid communication with a decomposition chamber 219 via an upper conduit 215 and a lower conduit 217. The decomposition chamber is in fluid communication with the vessel 205 via the head conduit 221 and is equipped with heating means, not shown.

This device converts heat into electrical energy. The sodium ions in plate 207 are attracted to the molten tin in vessel 201 , and the contents of that vessel can then be represented by the formula NaSn _x . Sodium atoms 209 donate electrons to conductor 211 and, as ions, replace the sodium ions attracted from plate 207 to tin 203. These electrons are returned via the external circuit and conductor 213 for use in the formation of NaSn _x in the vessel 201 . The reaction product NaSn _x goes via line 217 into the decomposition chamber 219 and is heated to the decomposition temperature. The sodium vapor goes overhead from the decomposition chamber 219 to the vessel 205 via line 221, while the molten tin is returned to the vessel 201 via line 215 .

Example 4

Crystalline cylinders measuring approximately 1 cm in length and approximately 1.2 cm in diameter were placed on manufactured in the following way:

1. Magnesium oxide was prepared by calcining a basic magnesium carbonate to a temperature of about 816 ⁰ C.

2. The magnesium oxide was _{mixed with finely divided Al 2} O ₃ as a slurry in benzene.

3. The benzene was evaporated.

4. The mixture of magnesia-alumina was then baked at about 1427 ° C for about 30 minutes.

5. The product obtained after 4 was mixed with sodium carbonate as a slurry in benzene.

6. The benzene was evaporated.

7. The mixture of magnesia-alumina-sodium carbonate was then at about Fired at 1427 ° C for about 30 minutes.

8. The powdered product according to 7 was then mixed with a customary wax lubricant (Carbowax) and pressed hydrostatically to form cylinders at around 7000 kg / cm ² .

9. The wax lubricant was removed by heating the cylinder in air while increasing the temperature over a period of 2 hours to about 800 ^° C. and maintaining this temperature for a further hour.

10. The cylinders were then packed in MgO crucibles with a packing powder of the same composition, ie the powder product according to 7, and ^{heated to 1900 °} C. in air for 15 minutes.

The composition of these cylinders was 6.3 percent by weight Na _2, 0.2.18 percent by weight MgO and 91.52 percent by weight Al ₂ O ₃ . The composition was determined by conventional chemical analysis, that is, sodium by flame photometry, magnesium by titration using Eriochrome Black T as an indicator, and aluminum from the difference.

Resistance measurements as a function of temperature over a range between room temperature to 500 ° C were made using one of these cylinders in an argon atmosphere. The results are graphed in FIG. 4 of the drawing. The weight of this cylinder was 316 g.

As in Fig. As shown in FIG. 5, a test cell was produced which consisted of a glass tube 313 as a cell container, which was fastened in a heating bath 311. The feed for liquid sodium pentasulfide 315 is shown in the bottom of tube 313 . The upper end of the tube 313 consists of a rubber stopper 317 through which a narrower glass tube 319 is inserted. The lower end of the tube 319 is sealed to a disk 321 and thereby closed, which consists of the resistance according to FIG. 4 examined cylinders was cut. A feed for liquid sodium 323 is shown in the bottom of tube 319 . A tungsten wire 325 extends through the top of the tube 319 into the liquid sodium 323. The top of the tube 319 is closed around the wire 325 . Also extending through the plug 317 is a nichrome tape electrode 327 which extends into the liquid sodium pentasulfide 315 to a position immediately below the disc 321 where it terminates in a loose loop.

Nichrome is an alloy of approximately 58.5 percent by weight Ni, 22.5 percent by weight Fe, 16 percent by weight Cr and 3 percent by weight Mn. A conductor 329 is electrically connected to the wire 325 . An ammeter 333 is electrically connected to the conductor 331 . A voltmeter 335 is located between conductors 329 and 331 and in electrical communication therewith.
In electrical connection with the terminals 337 and 339 of the conductors 329 and 331 is a pivotable switching device 341. The switch 341 can be periodically pivoted by the timer 343 so that the conductors 329 and 331 in electrical contact with the terminals 351 and 353 of a discharge circuit 350 which includes a conductor 355 and a variable resistor 357 , thereby completing a cell circuit and starting the discharge of the cell, sodium ions being transferred from the inner tube 319 to the Na ₂ S ₅ in the tube 313 . The switch 341 can also be pivoted by the timer 343 so that the conductors 329 and 331 are in electrical contact with the terminals 361 and 363 of a charging circuit 360

109 551/270

ίο

come, which consists of a conductor and a battery arrangement, the current output of which can be varied. This latter connection initiates a charge cycle, with sodium being fed from the _{chamber originally containing Na 2} S ₅ through disk 321 into tube 319 . By regulating the use of electricity, ie the charge voltage, in the charging operation and the load resistance during the discharge operation, the cell was operated so that the difference between the charge drawn from the cell and the charge delivered to the cell during a complete cycle was zero.

The open circuit potential of this cell was measured to be 2 volts. The cell was alternately charged and discharge every 30 minutes. The charge-discharge current was about Maintained 10 milliamps.

Two such cells, hereinafter referred to as cells A and B, were operated, the anodic and cathodic reactants being kept at a temperature of 300 ± 1 ° C. A comparative cell, hereinafter referred to as Cell C, was operated with these reactants maintained at 296 ° C ± 1 ° C. The comparative cell, on the other hand, differed from cells A and B only with regard to disk 321, which was manufactured in the following manner:

1. A mixture of sodium carbonate and Al ₂ O ₃ in relative concentrations corresponding to the eutectic mixture of beta-aluminum oxide and sodium aluminate, which melts at about 1590 ° C, was ground in a ball mill for 2 days and then by acid using a dilute solution of Leached HNO ₃ and HCl to remove sodium aluminate and traces of iron from milling. Beta alumina is usually given by the formula

Na ₂ O • UAl ₂ O ₃

reproduced. Sodium aluminate is usually given by the formula

2. A wax lubricant (Carbowax) was mixed with the powder and this mixture was hydrostatically pressed ^{into cylinders at about 7000 kg / cm 2.}

3. The wax lubricant was made by heating the cylinders in air while increasing the temperature for 2 hours to 600 ° C and maintaining this temperature for a further Hour drifted off.

ίο 4. The pressed cylinders were fired at about 1816 ° C in a carbon tube furnace under an argon atmosphere. The cylinders were surrounded with coarse particles (1 micron) of beta-alumina to prevent loss of caustic soda. The fired samples were chemically analyzed by the same methods listed above and showed a content of 5.75 percent by weight Na ₂ O and 94.25 percent by weight Al ₂ O ₃ . A disk cut from one of these cylinders with a diamond saw was used in the comparative cell.

The disk used in cell C, the comparative cell, was 2.8 mm thick and had an exposed surface area of 1.29 cm ² to the anodic reactant. The cylindrical disk used in Cell A was 3.28 mm thick and had an exposed anodic reactant surface area of 1.16 cm ² . The cylindrical disk used in Cell B was 2.17 mm thick and had an exposed surface area of 1.10 cm ^{2 of} the anodic reactant.

Since the crystalline disks used in the three test cells differ in terms of the exposure area, the change in the cell resistance values was brought into direct comparison by applying an A (R - J? ₀ ) factor in the following table, in which the following abbreviations are used:

Na ₂ O-Al ₂ O ₃

shown.

R = cell resistance (Ohm),
R ₀ = originally the cell resistance (Ohm),
t = time in days,
A = surface area of the non-conductive disk 321, which is made up of the anodic reactant

is set (cm ² ).

Table I Cell resistance and its change with time

7th ZeIIeA A (RR ₀ ) t 1 Cell B A (R-R ^ f Cell C A (RR ₀ ) t 10 R. 0 2 R. 0 0 R. 0 12th 6.96 -0.0975 3 5.70 +0.028 0.97 8.47 + 1.06 14th 6.88 -0.109 6th 5.725 -0.044 1.95 9.29 +2.28 18th 6.87 -0.147 8th 5.66 -0.066 4.68 10.24 + 5.24 21 6.84 -0.133 10 5.64 -0.088. 5.96 12.53 + 6.88 24 6.85 -0.219 14th 5.62 -0.077 7.90 13.80 +7.79 26th 6.78 -0.158 17th 5.63 +0.011 8.75 14.51 + 8.50 28 6.83 -0.061 20th 5.71 -0.22 9.89 15.06 +9.68 31 6.91 -0.121 22nd 5.50 -0.088 10.81 15.97 +9.75 6.86 -0.024 5.62 -0.44 11.80 16.03 + 10.38 6.94 5.66 16.52

continuation

Cell A A [RR ₀ ) I. Cell B A [RR ₀ ) 12.85 Cell C .-4IR-R ₀ I. f R. -0.037 24 R. -0.055 13.95 R. + 10.75 33 6.93 +0.012 27 5.65 -0.12 14.78 16.80 + 11.84 35 6.97 +0.024 5.59 16.05 17.65 + 11.87 39 6.98 +0.086 18.70 17.67 + 11.80 45 7.03 +0.158 19.80 17.62 + 12.44 47 7.09 +0.219 20.95 18.11 + 12.45 49 7.14 + 0.268 21.90 18.12 + 11.79 52 7.18 +0.305 23.0 17.61 + 12.24 54 7.21 +0.130 17.96 + 11.96 56 7.07 +0.182 17.74 59 7.11 +0.293 61 7.20 +0.316 63 7.22 +0.426 66 7.31 +0.389 68 7.28 +0.486 70 7.36 +0.535 73 7.40

The above changes in the total cell resistance in cells A and C as a function of of time are graphed in FIG. 6 of the drawing.

Example 5

Crystalline cylinder of about 1 cm χ about 1.2 cm were prepared according to the first indicated in Example 4, the preparation of the Na ₂ 0-MgO-Al ₂ O ₃ that is cylinder.

The electrical resistance (direct current) of each cylinder was measured in air space temperature, i.e. H. 20th determined up to 25 ° C. The

cylinder to be examined between filter papers saturated with sodium hydroxide solution (5 n), 35 interposed.

The opposite sides of the stack were each in connection with Ag / AgO electrodes, that were electrically connected to an ohmmeter.

The properties of these cylinders are summarized in the table below.

Table II Electrical resistances of Na ₂ O — MgO — Al ₂ O ₃ cylinders

Attempt
description
(No.) Weight percent of the composition
the crowd cylinder
No. Electrical resistance
(Ohm cm) weight
of the cylinder
G 126 MgO - 2.33 1 348 2.86 2 292 2.79 Na ₂ O - 7.13 3 220 2.93 4th 278 2.78 Al ₂ O ₃ - 90.54 5 342 2.91 6th 294 2.86 7th 330 2.82 8th 230 2.91 9 275 2.82 10 294 2.90 11th 256 2.79 12th 296 2.82 average 289.58

continuation

Attempt
description Weight percent of the composition
the crowd cylinder
No. Electrical resistance weight
of the cylinder (No.) (Ohm ■ cm) 8th 123 MgO - 2.02 1 308 3.0 2 320 2.78 Na ₂ O - 8.14 3 335 2.98 4th 340 3.02 Al ₂ O ₃ - 89.84 5 400 2.93 6th 355 3.0 7th 325 2.88 8th 325 2.88 9 310 3.06 average 335.62 124 MgO - 1.72 1 378 3.05 2 407 2.99 Na ₂ O - 8.24 3 354 2.95 4th 420 3.01 Al ₂ O ₃ - 90.04 5 322 3.05 6th 346 3.06 7th 372 3.01 8th 352 3.03 average 368.87 120 MgO - 2.81 1 425 2.91 2 530 2.90 Na ₂ O - 8.13 3 550 2.93 4th 540 2.90 average 511.25 111 MgO - 3.34 1 654 2.88 2 654 2.80 Na ₂ O - 10.31 3 896 2.80 4th 764 2.80 Al ₂ O ₃ - 86.35 5 957 2.81 6th 757 2.90 average 930.33 119 MgO - 1.51 1 1040 3.12 2 1020 3.13 Na ₂ O - 7.19 3 840 3.12 4th 1420 3.11 Al ₂ O ₃ - 91.30 average 1080 117 MgO - 0.93 1 3020 3.02 2 2200 3.0 Na ₂ O - 7.47 3 ι 2900 3.01 4th 2100 2.9 Al ₂ O ₃ - 91.60 average 2555

15th 1 596 078 16 weight
of the cylinder
G continuation Electrical resistance
(Ohm cm) 2.73 Attempt
description
(No.) Weight percent of the composition
the crowd cylinder
No. 264 3.04
3.02
3.12 91-n MgO -
Na ₂ O -
Al ₂ O ₃ - 1 282
340
380
average
334 3.04
3.05
3.04 104 MgO -
Na ₂ O -
Al ₂ O ₃ - 1
2
3 1280
1240
1210
average
1263 118 MgO -
Na ₂ O -
Al ₂ O ₃ - 1
2
3 - 2.66
- 7.38
- 89.96 - 2.78
- 8.81
- 88.41 - 0.62
- 7.42
- 91.96

Example 6

Cylinders were made according to the first procedure described in Example 4 with the exception that Li ₂ O was used in place of MgO and different sintering temperatures were used.

The electrical resistance (direct current) of each of these cylinders was determined as in Example 5.

The composition of each batch of these substances was determined by chemical analysis after the last Stage determined before sintering. Composition, electrical resistance and weight of the individual cylinders and the sintering temperatures for the respective batches are summarized in the following table.

Table III Electrical resistances of Na ₂ O - Li ₂ O - Al ₂ O ₃ cylinders

Approach no. Weight percent of the total
setting the approach Cylinder no. Electric
resistance weight
of the cylinder Sintering temperature (Ohm ■ cm) G ⁰ C 85 Na ₂ O - 8.62 1 7 450 2.58 1720 2 5 100 2.75 1720 Li ₂ O - 0.83 3 6 200 2.68 1720 4th 8 590 2.48 1850 Al ₂ O ₃ - 90.55 5 2,670 2.88 1850 6th 2 100 3.01 1850 87 Na ₂ O - 9.0 1 427 3.09 1720 2 383 3.06 1720 Li ₂ O - 0.7 3 250 2.84 1850 4th 4 100 2.82 1850 Al ₂ O ₃ - 90.3 89 Na ₂ O - 9.0 1 1950 2.76 1900 2 3,550 2.72 1900 Li ₂ O - 0.7 3 4 600 2.48 1900 4th 3,200 2.74 1900 Al ₂ O ₃ - 90.3 5 2,200 2.82 1900 6th 2,500 2.81 1900 90 Na ₂ O - 11.87 1 34,000 2.84 1700 2 14,000 2.83 1700 Li ₂ O - 1.64 3 22 200 2.68 1700 4th 26 700 2.62 1700 Al ₂ O ₃ - 86.49 109 551/270

Example 7

Cylinders were made according to the first procedure described in Example 4 with the exception that NiO, ZnO and CoO were used instead of MgO and different sintering temperatures were applied.

The electrical resistance (direct current) of each of these cylinders was determined as in Example 5.

The composition of each batch of these substances was determined by chemical analysis after the last Stage determined before sintering. Composition, electrical resistance and weight of the individual cylinders as well as the sintering temperatures used for the respective approaches are in the following Table summarized.

Table IV

Electrical resistances of Na ₂ O - NiO-Al ₂ O ₃ - Na ₂ O - ZnO-Al ₂ O ₃ - and Na ₂ O - Al ₂ O ₃ CoO cylinder locks

Approach no. Weight percent of the approach
composition Cylinder no. Electric
resistance weight
the cylinder Sintering temperature (Ohm cm) G ⁰ C 95-2 Na ₂ O - 8.65 1 1665 3.18 1800 NiO - 6.66 2 1850 3.14 1800 Al ₂ O ₃ - 84.69 113 Na ₂ O - 8.65 1 1070 2.89 1900 NiO - '6.66 2 1700 2.90 1900 Al ₂ O ₃ - 84.69 3 995 2.93 1900 95-1 Na ₂ O - 8.70 1 ■ 1370 3.12 1800 ZnO - 5.86 2 2350 3.02 1800 Al ₂ O ₃ - 85.44 95 Na ₂ O - 8.64 1 1035 3.21 1800 CoO - 6.67 2 945 3.20 1800 Al ₂ O ₃ - 84.69

Example 8

Crystalline cylinders approximately 1 cm long and 1.2 cm in diameter were made according to prepared according to the first procedure described in Example 4 except that the relative amounts the components have been changed in the following manner. If different sintering temperatures were applied, this is also indicated.

Cylinders were made in this way from the components that were just prior to sintering the following analysis showed:

Na ₂ O - 7.93 weight percent
MgO - 3.44 percent by weight
Al ₂ O ₃ - 88.63 weight percent

The cylinders were sintered at about 1850 ° C for 30 minutes. The individual cylinders were then subjected to chemical analysis, and the sintered composition gave the following analysis:

Na ₂ O - 7.71 weight percent

MgO - 3.81 weight percent

Al ₂ O ₃ - 89.42 percent by weight

Electrical resistance (direct current) measurements were made on these cylinders as in the previous examples. These ranged from about 318 to about 500 ohm · cm. Another group of cylinders were made in the same manner except for the relative amounts of the ingredients. Chemical analyzes of selected cylinders after sintering showed that these cylinders contained about 3.94 percent by weight MgO, 8.49 percent by weight Na ₂ O, ReStAl ₂ O ₃ . Eleven of these cylinders were stacked vertically for sintering, with the hottest point in the furnace being in the face of cylinder number 4. The temperature at this point was 1900 ⁰ C. The weights and those for these

Cylinder specific electrical resistances were as follows:

weight Electric Cylinder no. G resistance 3.03 (Ohm cm) 1 2.91 ' 468 2 2.91 317 3 2.98 284 4th 2.94 190 5 3.02 475 6th 3.96 604 7th 2.98 510 8th 2.93 695 9 3.02 640 10 2.83 595 11th 730

IO

20th

Another set of cylinders were made in the same manner, compression ^{molded at about 280 kg / cm 2} and hydrostatically pressed at 7700 kg / cm ^2. Selected examples were analyzed and the following results were obtained:

Na ₂ O - 7.77 percent by weight MgO - 3.81 percent by weight Al ₂ O ₃ - remainder,

These cylinders were ^{fired at 195O 0} C and examined with regard to the electrical resistance (direct current) as in the preceding examples.

The results obtained are summarized below:

40

45

The crystalline structure of selected cylinders of the alumina-sodium oxide-magnesia bodies from Example 8 was determined by X-ray diffraction analysis, a pattern being repeatedly obtained which is similar to, but clearly distinguishable from, the pattern described by T hery and Briancon, Comptes Rendues, Vol. 254, p. 2782 (1962), which these authors attribute to _{a compound NaAl 5} O _8. The compound described there is not stable ^{above about 1500 to 1600 ° C.}

The crystalline structure of selected cylinders of the aluminum oxide-sodium oxide-magnesium oxide bodies according to Example 1 resulted in an X-ray diffraction pattern which is completely different. This scheme is of the type obtained for Na ₂ O · HAl ₂ O ₃ .

_{Example9 6j}

Sheets of the trimetal oxides prepared according to the method of Example 4 according to the invention continued to manufacture

• Electrical resistance Cylinder no. (Ohm cm) 1 470 2 318 3 370 4th 338 5 430 6th 500

elemental metal of exceptionally high purity from an ionizable compound of the to be extracted Metal used. In this use, the plates served as an ion filter through which the applied Voltage and the current flow obtained drive the ions to be extracted as elemental metal.

When using a cell as shown in FIG. 1, a molten eutectic mixture of NaNO ₃ and NaNO ₂ at 245 ° C. is introduced into the tube 31 of FIG. 1 resulting pipe given. The plate or disk corresponds to the disk 21 according to FIG. 1 and is used for ion filtering. A small amount of molten sodium is poured into the tube of FIG. 1, and a direct current from a direct current source connected to the external circuit is passed through the cell via the conductors 17 and 19 of FIG. 1 corresponding conductor led. The applied potential is regulated so that the conductor 17 becomes more negative than the open circuit voltage of the cell. Sodium ions leave the mixture, migrate through the plate, and elemental sodium is recovered.

In Fig. 4 shows the determination of the resistance with alternating current of the Na ₂ O — MgO — Al ₂ O ₃ cylinder as a function of the temperature at the frequencies specified there - impedance bridges - Wayne-Kerr B 221 and 601.

Claims (8)

Patent claims: 1. Cationically conductive, crystalline solid electrolyte consisting of a mixed crystal lattice and cations, which migrate with respect to the crystal lattice under the influence of an electric field, thereby characterized in that the crystal lattice consists essentially for the greater part of ions of aluminum and oxygen and, to a lesser extent, ions of a metal with a valence is not greater than 2 and has cations that are under the influence of an electric field hike. 2. Electrolyte according to claim 1, characterized in that the cations of alkali ions, in particular Sodium ions. 3. Electrolyte according to claim 1 or 2, characterized in that the ions of the metal with a Valence not greater than 2 consist of magnesium or lithium ions. 4. Process for the production of crystalline electrolytes according to claim 1 to 3, characterized characterized in that a major proportion by weight of aluminum oxide and a balance of one larger proportion by weight of sodium oxide and a smaller proportion by weight of an oxide of a metal are thoroughly mixed with a valence not greater than 2, the resulting mixture on Crystal formation temperature is heated, the obtained crystals to the desired shape and Compressed size and the compacts are sintered. 5. Application of the electrolyte according to claim 1 to 3 in galvanic elements that have an anodic Reaction zone with a negative electrode and a cathodic reaction zone with a positive electrode, with the solid electrolyte as a half-cell separating layer between the anodic reaction zone and the cathodic reaction zone is attached. 6. Application of the electrolyte in a galvanic element according to claim 5, characterized characterized in that the anodic reaction zone is at a higher temperature and a higher Pressure is maintained as the cathodic reaction zone. 7. Application of the electrolyte according to claim 1 to 3 in an electrochemical process for Deposition of an alkali metal from a molten salt thereof, whereby the molten Salt in contact with the solid electrolyte is brought as a half-cell separating layer and an electrical potential difference between the Side of the separating layer that is in contact with the salt and the opposite side with such polarity is applied that there is a flow of the cations of the metal from the salt and results in one direction through the release liner. 8. Use according to claim 7, characterized in that the molten alkali salt a sodium salt is used. For this purpose 2 sheets of drawings