DE8230321U1 - ELECTROCHEMICAL ELEMENT - Google Patents

Description

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CENTRA-BÜRKLE GmbH + Co

7036 Schönaich.

Electrochemical element

The invention relates to an electrochemical 20

Element according to the preamble of the claim

A well-known electrochemical element of this type is the Daniell element ("Lexikon der Physik",

Franckh'sche Verlagshandlung Stuttgart, 2nd edition, 25

1959, page 199}, which the system Cu / CuS0 ₄ / ZnS0 ₄ / Zn

upstairs. The acidic zinc and copper sulphate solutions that form the two electrolytes, both of which have pH values below 7, are separated by an _ori porous clay wall. Bsi electricity delivery goes

Zinc of the zinc electrode forming the negative anode in solution, with the positive zinc ions being the negative SO ions through the porous clay wall pull over to you, · The released positive gg copper inner migrate to the second electrode, which the

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35

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, 5 forms positive cathode and is a copper plate. '^; The opposite reactions occur when charging

away. The Daniell element thus forms a secondary element. It has, inter alia. the disadvantage that its Energy density and therefore its capacity relative

I 10 is small because it serves as the second electrolyte I copper sulphate solution quickly becomes depleted because the

f S0 ₄ ~ ions of the copper sulphate

\ solution in the first electrolyte forming

“'' Zinc sulphate solution migrates more quickly with the result

15 exhaustion of this secondary element. Also, mixing of the two electrolytes inevitably occurs

I enter through the porous clay wall as it

I must have such permeability that the negative

I acid residues SO _{4 of} the second electrolyte as a carrier

I 20 of the negative charges in the first electrolyte

can immigrate. This necessary * permeability I for the acid residues "SO ₄ '^1" makes the porous

\ Clay wall necessarily also for the metal ions

'Zn and Cu of the electrolytes are permeable because these

: 25 lower atomic weight than the molecular

corresponds to the weight of the acid residue SO _4. The Danielll was therefore unable to do anything worth mentioning

into practice and essentially only played in the. Beginnings of electrical engineering the role of a voltage norcal.

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For the avoidance of impoverishment of the besdhriebeneri Kupfersülfatlösung a Meidinger element was known, was provided in which .the by a storage vessel with copper sulfate crystals for maintaining the concentration ¹ Kupfersülfatlösung of Daniell elemene tes. However, this is structurally complex and nevertheless does not prevent the element from being exhausted relatively quickly and its rapid self-discharge. with a given capacity (in Whi) it requires a relatively large volume.

It is therefore an object of the invention to provide an electrochemical element of the type mentioned at the beginning Art to create, which have low self-discharge, long service life and high energy density can.

This object is achieved according to the invention by an electrochemical element according to claim 1 .

This electrochemical element according to the invention exhibits only very little self-discharge. The second electrolyte is not exhausted _f because when discharging OH ions form the charge carriers and, if it is a secondary element, when charging H-KE ions form the charge carriers in the electrolyte, which migrate through the partition. The molecular weight of the OH ions is very low, namely 37 and

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25th

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the atomic weight of the unions is even only 3. In any case, this molecular weight or this atomic weight is smaller than the atomic weight of the metal ions in the second electrolyte, if / as preferred, the second electrolyte contains at least one metal compound in dissolved form. It is also possible to provide the second electrolyte in such a way that the chemical compound dissolved in it is not a metal compound but, for example, an aqueous ammonia solution. The ammonia NH ₄ Cl forms in the water with elimination of the chlorine NH ₄ OH molecules / whose molecular weight is 35, i.e. more than twice as large as that of the OH ions. It can therefore always be formed so that the dividing wall separating the first from the second electrolyte that they both the '. Metal ions contained in the first electrolyte, as well as metal ions contained in the second electrolyte or other molecules with larger molecular weights than that of OH molecules does not let through, but only the OH ions and of course the Η ions, as these have an even lower atomic weight. Furthermore, the partition can expediently be chosen so that the solvents of the electrolytes, which then have an identical chemical constitution, preferably water, can also pass through.

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The element according to the invention can also be used as a non-chargeable Primary element are formed. Also, in this case the partition wall must not be permeable his for the acid residues contained in the first electrolyte.

Another advantage of inventive elements that they can get very high energy density because they require only small amounts of electrolytes because they do not deplete during unloading. In general, the electrolytes can expediently be liquids, but optionally also have a paste-like character, or at least one electrolyte can be absorbed in a porous carrier medium.

The volume of an element according to the invention can be very small as a result of the low electrolyte requirement being held. Elements according to the invention can also be and are relatively inexpensive to manufacture In addition, it is environmentally friendly as it does not contain any toxic components, such as B. mercury and cadmium too need to contain.

The element according to the invention is distinguished in the case of its formation or its use as Secondary element is also characterized by the fact that it is subjected to very large numbers of charge and discharge cycles can be. In contrast to the known metal-oxygen secondary elements, which are mostly designed as metal-air secondary elements, no dendrites on the first when loading

I S472 = 14 "

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5 electrode. The invention thus remedies with one; Beat all of the previously known metal *

; Oxygen elements through the when loading at the

dendrites arising from the first electrode ] Difficulties affecting the practical use of the

iÖ well-known metal-oxygen elements prevented and at least the number of

I greatly reduce the available charge and discharge cycles,

I so that metal-oxygen secondary elements

; ■ "■ not yet against the much more expensive ones

| i 15 and less environmentally friendly elements of lead

and nickel / cadmium batteries were able to prevail. Thus, the invention also resolves this far in. '■ metal-oxygen secondary elements existing

basic difficulties in a simple way. 20th

* The when unloading the element according to the invention

immigrating from the second to the first electrolyte OH ions can interact with the metal

_{; i} first electrode or with. in the first electrolyte

,} ^ contained metal ions enter into at least one compound I, in particular metal hydroxide and / or

A metal oxide form, optionally from the first

'ύ Electrolyte is precipitated, but in the

^B first electrolyte-containing area of the element

30th

remains. When training the invention

As a secondary element, positive Η ions migrate through the charging from the second electrolyte Partition wall through into the first electrolyte

and reduce the 35 formed in it during unloading

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Metal compound or compounds too positive charged metal ions and water molecules. The metal ions then migrate to the first electrode and unite with the metal atoms already on it so firmly that the first electrode is a solid electrode, the thickness of which is continuously attached to it when it is charged Metal ions grows roughly evenly. In particular, no dendrites are formed and none either granular, easily wipeable deposits of to it arriving metal ions. This regression of the first electrode during charging to a turn massive, inherently solid electrode of approximately uniform thickness, very high numbers of chargers and discharge cycles. The invention thus in particular also creates the possibility of Metal-oxygen secondary elements with previously unattainable high numbers of charge and discharge cycles to accomplish. In the aforementioned dendrites, which are found in the known metal-oxygen secondary elements arise during charging and not in the case of metal-oxygen secondary elements according to the invention more arise, it is a needle-shaped structure that emerges from the first electrode during charging outgrowth and which can easily break off and which are also easy to short-circuit and generally right quickly lead to the secondary element becoming unusable.

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Under a metal-oxygen Element'ist also _he ä> case understood that it is, a so-called metal-air element is, in which therefore the oxygen supplied by the ambient atmospheric air. If necessary, it is also possible to take the oxygen from other sources, for example to provide pure oxygen or to take it from a reservoir, for example manganese dioxide, as is the case with the Leclanche element. The latter can in particular come into question if the element according to the invention is provided as a primary element, that is to say is not rechargeable. Compared to the known Leclanche element, which has a single electrolyte, a primary element with manganese dioxide as the oxygen carrier designed according to such a development of the invention has the advantage, among other things, that higher voltages can be provided instead of zinc for the first electrode , Preferably · * »aluminum. The first electrolyte is then an aluminum salt solution, for example an aqueous aluminum sulfate solution. An aluminum-oxygen element according to the invention (including an aluminum-air element) theoretically enables electrical voltages of approx. 2.7 volts, that is to say

^ ® are very high, regardless of whether it is used as a primary element or a secondary element. With such an aluminum-oxygen element, you can use batteries of a predetermined DC voltage with a smaller number of elements connected in series than with the most common today

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Lead -. 'Accumulators or. Nickel / cadmium batteries achieve.

When the element according to the invention is designed as a metal-oxygen element, the oxygen cathode ai _e forms the second electrode, which forms the positive pole of the element during discharge. As mentioned, the oxygen can preferably be supplied by atmospheric air. The oxygen catalyst can preferably contain activated carbon powder as a catalyst. In the active carbon powder

or directly adjacent to it, a metal perforated plate or grid in contact with the activated carbon «- be powder to which the positive pole of the element is galvanically connected. This positive pole can both the positive pole when discharging and the positive in the case of a secondary element Form a pole when charging. However, it is also possible and can preferably be provided that the element in the case of training as a metal-oxygen secondary element has a third electrode to which the positive pole of the charging current source is connected for charging, The third electrode is outside the active carbon powder but still inside the second Electrolyte is located., Dias has the advantage that it forms on the third electrode during charging

\ atomic oxygen is kept away from the activated carbon

jf can be, so does not need to get to her,

Atomic oxygen can do activated carbon

oxidize and thus prevent the aging of the element
to accelerate. Since the element according to the invention is very

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Can withstand many charging and discharging cycles, it ages very slowly and it is therefore particularly useful to also switch off the oxidation of the activated carbon, which is a source of aging, which can be done by the described measure of the third electrode, which is not changed during charging . The dividing wall separating the first and second electrolytes can be of any suitable configuration which gives the properties described in claim 1. In the simplest case, they may be ■ a single molecular sieve, the separation limit is greater than 17, so that OH ions can pass through them. The separation limit of a molecular sieve is understood to mean that it lets through molecules with a molecular weight less than the separation limit and does not let through molecules with a molecular weight greater than the separation limit. In the invention, the separation limit of the molecular sieve must therefore be greater than 37, but it must not be too large, but must be such that the metal ions of the first electrolyte participating in the electrochemical reactions taking place during discharge and, if necessary, also of the second electrolyte ^u does not let through, likewise not acid residues of the first electrolyte and undissociated hydroxide compounds present in the second electrolyte, such as. B * Potassium hydroxide if the second electrolyte is potassium hydroxide.
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The first electrolyte is preferably an acidic electrolyte, the pH of which is then less than is. However, it is also conceivable that in many cases its pH is expediently a-uch equal to 7 or et · ^ which can be greater than 7. A pH of 7 or something greater than 7 assumes that the first electrolyte does not only contain metal salt in solution, but at least one basic additive that brings its pH to 7 or a little above raises. This leads to the fact that the metal oxide detaches itself to an increased extent when discharging and, if that The solvent of the first electrolyte is water, less water in the metal hydroxide when discharging 'is bound. The water consumption during unloading is therefore lower and the water supply in the element can be given a correspondingly smaller volume and thus the element can have a somewhat smaller volume.

The second electrolyte can expediently have a pH value greater than 7, since this makes it relatively high Discharge currents of the element can be achieved. However, it is also possible in special cases to adjust the pH of the second electrolyte should be set to approximately 7 if relatively low discharge currents are sufficient. It it should also be mentioned here that the discharge currents can also be increased by using the second Forms electrode made of noble metal, but this is expensive and uneconomical. Preferably the The second electrode can be a cheap oxygen electrode or, if it is made of metal, it can

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expediently consist of a cheap metal that is positive towards the first electrode when discharging is.

Let us give an example of the range in which the separation limit of a molecular sieve must be if it alone forms the dividing wall: It is assumed that the first electrode is made of zinc and the second electrode is an air electrode. The first electrolyte is an aqueous zinc sulfate solution and the second electrolyte is potassium hydroxide solution, i. h an aqueous KOH solution, the partition should then be permeable to water, H and OH ions. On the other hand, it should not be permeable to the metal ions, KOH vind SO ^. The metal ions have atomic weights of 65.4 (zinc or 39.3 (potassium! * The acid residue SO ₄ has a molecular weight of 96, KOH of 56.1), so the separation limit of the molecular sieve must be greater than that of water and smaller than that of potassium , between 18 and 39.1. If the partition is designed as a single molecular sieve, the potassium ions of the second electrolyte must not be able to pass through the molecular sieve, since they have a strong affinity for the acid residue SO ₄ of the zinc sulfate and would therefore migrate into the first electrolyte and generate dendrites there during charging.

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Molecular sieves are more expensive, the smaller their separation limit is and the larger it is Resistance that they have to the ion migration when load or load opposite. It is therefore on

it is desirable to be able to use molecular sieves with a relatively large separation limit. This succeeds according to a Further education ··. in that the dividing wall is not formed from a single molecular sieve, but from two molecular sieves and a third electrolyte located between them consists. It is then possible, with the use of a suitable third electrolyte, to achieve that the separation limit of the two molecular sieves is greater than the atomic weight of those in the second electrolyte Can be metal ions, which can preferably be alkali metal ions, especially about potassium, sodium or lithium ions, and indeed such alkali metal ions have strong ones Affinity for the primarily possible acid residues of the first electrolyte, for example to SO .. However, this affinity cannot break out if the third electrolyte is selected in such a way that it contains the metal ions of the second Elektrcblytan lose their ability to do that between the third and the first electrolyte located molecular sieve to pass.for this purpose the third electrolyte should preferably be selected so that it has dissolved metal • salt contains, wherein the solvent can expediently correspond to the solvent of the first and the second electrolyte. The metal of the third

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Electrolyte dissolved metal salt can preferably corresponds to the metal of the second electrolyte and the acid residue corresponds to the acid residue of the first electrolyte.

If, for example, the first electrolyte consists of aqueous zinc sulfate solution and the second electrolyte consists of potassium hydroxide solution, the third electrolyte can expediently consist of potassium sulfate (K ^ SO.). It is sufficient if, in this example, the separation limit of the molecular sieves is less than the molecular weight of KOH (potassium hydroxide), although it may be greater than the atomic weight of potassium, ie greater than 39.1 and less than May be 56.1, for example the separation limit may be 50. Every molecular sieve is then permeable to the potassium ions per se, and of course to H, OH and H ₃ O, but not to KOH, Zn and SO .. Although the potassium ions themselves pass through the molecular sieves. however, at least they do not pass through the molecular sieve of a separation limit which separates the third electrolyte from the first electrolyte

39.1 and less than 56.1 through, because the in cTreit Potassium atoms in electrolytes at all ° 0 do not have the tendency through the third Separating electrolyte from the first electrolyte. Molecular sieve to migrate whatever to their bond to those in the third electrolyte

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SO.-ions should be attributed. To have *

the metal ions in the second electrolyte, e.g. B. potassium ions, normally high affinity for the acid residues in the first electrolyte, for example SO ₄ . By the described design of the partition, according to which it consists of two molecular sieves and the third. If there is an electrolyte, this affinity does not develop because the same acid residues are already present in the third electrolyte and the acid residues bound to these acid residues are already present

^ g metal ions then no longer have an affinity to the dei the same acid residues in the first electrolyte. In this way, one designed in this way acts Partition for metal ions of the second electrolyte, even if these two molecular sieves for these metal ions are per se permeable, like a barrier that their transition into the first electrolyte prevented. It is also conceivable that the acid residues in the first and third Electrolytes can be chemically different.

It is important that the partition, if its molecular sieves for metal ions or the like second electrolytes are permeable, which should not get into the first electrolyte, the third electrolyte, the affinity of these metal ions or the like for the acid residue in the first electrolyte so lowers or completely eliminates that these metal ions or the like from the third electrolyte do not migrate into the first electrolyte.

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Draw metal-oxygen elements formed according to the invention through very high energy densities, low weight and long service life, as well as in the case of training as a secondary element due to the large number of charging and discharging cycles that can be achieved.

Although it is preferred that the |

The electrochemical element is a metal-oxygen element, but it is also possible to train it so that its second electrode is also a metal electrode. This second The metal electrode must be designed in such a way that it forms the positive cathode when it is discharged. For example this second electrode could consist of nickel and the first electrode of zinc or aluminum. Other metals are also coming for the two metal electrodes. Important is that even with such an element having two metal electrodes, the second electrolyte is during the discharge OH ions continuously develop, which can migrate to the first electrode as charge transport carriers.

The first electrode of the element can in many cases be loaded with | An aluminum electrode is a particular advantage, as it has a particularly high electrical voltage of the new type Element allows. Aluminum is also inexpensive and lightweight, and is also trivalent. Aluminum thus enables the creation of elements with a particularly high energy density,

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struggle with weight and volume. However, other metals can also be used for the first electrode are, preferably zinc or magnesium> or, for example, iron, lithium or the like.

According to a further development of the invention it can be provided that the first electrode is alloyed with small amounts of alkaline earth metal and / or that the first electrolyte contains undissolved alkaline earth hydroxide, preferably calcium hydroxide, which is dissolved in the first electrolyte when the element is charged for the first time , so that the alkaline earth metal is then deposited on the first electrode together with the main metal of the electrode when it is charged for the first time. In the latter case, the procedure can be so that the massive first electrode is only formed by the first charge by placing a metallic carrier, e.g. B. a metal lid of the container ·, the element provides and in which the first electric

lyte containing chamber metal hydroxide, e.g. B.

in pasty form, from which the main metal for the first electrode is then split off during charging, which metal then migrates to the said metallic carrier and is here in massive, with the charging of the thicker layer precipitates as the first electrode. Less due to the addition Amounts of alkaline earth metal to the main metal of the first electrode can cause the deposition of the metal ions of the main metal on the first electrode

can be further improved when loading in accordance with 36

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even better uniformity of the deposition of the metal ions of the disassociated in the first electrolyte Metal salt to the first electrode when charging. The addition of alkaline earth metal can be small, be for example five percent by volume of the main metal of the first electrode. Of the The first electrolyte can contain exclusively or essentially only metal ions that correspond to the correspond to the metal salt dissolved in it. If it still contains at least one other metal dissolved in it, can do this in order to achieve special effects

, j- be provided, such as preferably the one described above Addition of small amounts of alkaline earth metal. The first electrolyte can be used as a metal salt suitably contain metal sulfate and / or metal nitrate and / or metal chloride in solution.

If several different metal salts are dissolved in the first electrolyte, their metal is 'Expediently the same metal, for example aluminum. If necessary, there are also other metal salts in question, for example Meta.l! bromide, metal iodide or the like. Preferably, the first electrolyte may contain a single metal salt.

At least one electrolyte can be an aqueous solution, i. H. contain water as a solvent. However, in some cases, other solvents are also used conceivable, preferably alcohols and their derivatives.

The second electrolyte can preferably be an aqueous one Be alkali. For example, the second 35

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The electrolyte is a potassium hydroxide solution which contains 20-45 percent by weight of potassium hydroxide. Electrochemical elements according to the invention can be designed or used in a position- ^{independent 1 or position-dependent manner.} If the element is completely closed to the outside, it can easily be designed as a position-independent element, be it as a primary element or as a secondary element.

If elements of the invention as secondary elements are rechargeable _t are such that no, in many cases

- _r know position-dependent text of the regression of its metal electrode or metal electrodes during recharging. This is explained using an example. If the first electrolyte is so affected that metal hydroxide is formed in it during discharge

2Q is made, then this superimposed at rest element according to gravity from * stands the element so that this metal accumulates at a position where the back split off from it be metal ions would not migrate evenly to ¹ the first electrode during charging , the first electrode can then be thickened in the vicinity of the accumulated metal hydroxide, which can become thick and thick in the course of several or many charging cycles. However, this is not a question of dendrites, so that such thickenings do not normally interfere and only after a large number of charging cycles, possibly.

5472 - 28 -

can disturb. However, if the risk of such thickening interferes, one can easily switch to the operating position of the element so that the metal hydroxide is uniform with respect to the first electrode deposited on the partition wall, in that the partition wall is approximately flat. extends approximately horizontally and vertical maintenance? which is arranged to it preferably approximately parallel to the first electrode. At im Operation of stationary elements, for example for elements that save Serving solar energy can be done without any problems. this approximately horizontal extension of the Provide a partition. Conversely, when the element is in a vehicle that is subject to fluctuations while driving is arranged in the frame of a battery, then the powdered deposited metal 1 is hydroxide during operation of the vehicle constantly by shaking and

^ ® shaking i ⁿ kept substantially uniform distribution and including loading is thus formed, the first electrode with approximately uniform thickness anwachsender back. The element can then be used in this case, despite the precipitation of metal hydroxide during unloading, practically independent of its position, provided that the metal hydroxide is largely kept in suspension by the shaking and shaking of the moving vehicle. If on the other hand, too.

when the vehicle is moving, the metal hydroxide

accumulates at a certain point on the element while walking or following the force of gravity,

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it is also appropriate _t it so

_ to arrange / that its partition wall in the rest area

condition of the vehicle is directed approximately horizontally.

It goes without saying that the invention is not based on an approximately planar design of the first electrode and the partition wall and possibly the second and / or ^ l * "» t + ör \ electrode is limited. Other trainings are also possible, e.g. concentric arrangement of electrodes and the partition.

Elements according to the invention can preferably be assembled to form batteries or accumulators, which because of their high energy density, their small volume and their low weight, inter alia. also excellent as accumulators for storage

solar energy and also suitable for use in motor vehicles.

As mentioned above, electrolyte is suitable for the second preferably alkali. In some cases, however, other solutions for the second electrolyte can also be used come into question, in particular solutions with a basic reaction, for example aqueous ammonia solution.

An exemplary embodiment of the invention is shown in the drawing.

The single figure shows a schematic representation of a longitudinal section through an electrochemical
Metal-air secondary element 10, which is a purpose

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Access of air to his hole bottom 18 on feet 18 'ste ¹ - ff
I has 5 existing, pot-shaped container 16 made of plastic;

I in the ceiling 44 a vent hole 4 5 and on its

( rigid, horizontally straightened, flat perforated plate

t> ended flat bottom hole 18, the air electrode 11

I is arranged »This air electrode 11 has a

> .Q horizontal, even layer of activated carbon powder 12

,; as a catalyst that works together with a

i · second liquid electrolyte 25 and one

flat, horizontally aligned perforated metal sheet 13

the space between one on the hole 15 Gas-permeable, but liquid-impermeable diaphragm 14 resting on the floor 18

and a gas- and liquid-permeable flat filter 15, for example a caustic ; · Be a durable non-woven fabric made of synthetic fibers

Ί 20 can and whose pore size is smaller than the grain size of the activated carbon powder 12 is filled.

The perforated metal plate 13, the holes of which are filled with the activated carbon powder 12, lies on the 25 diaphragm 14 open. The activated carbon powder 12 is sufficient

■ but over the perforated plate 13 also up to

■ ^fi to filter 15.

The perforated metal sheet 13 consists of a metal, 30 which reacts neither when charging nor when discharging the element 10, for example made of nickel. This perforated plate 13 is galvanically connected to the positive discharge terminal 19, that is, during discharging of the element 1O whose positive pole 19 forms. 35

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At a distance above the filter 15 extends a second, gas and liquid permeable, flat, metallic perforated plate 20 horizontally and parallel to it, which is galvanically connected to the positive charging pole 21 of the element 10 is connected. A positive charging voltage is applied to this positive charging pole 21 during charging created. At a short distance above this perforated plate 20, which forms a third electrode, is a flat and also horizontally extending partition, designated as a whole by 22 arranged, which consists of two spaced, flat, horizontally parallel to each other.

x5 mutually extending molecular sieves 23, 23 'and a third liquid electrolyte 24 filling the space between them.

The second electrolyte 25 fills the space between the diaphragm 14 and the molecular sieve 23 ' and can also be suitably liquid.

At a distance above the partition 22 is a plate-shaped, flat, also horizontal extending, massive first electrode 27 made of metal, which is arranged on a plate-shaped, flat support 2fa is. The carrier 26 consists of plastic, the underside with a vapor-deposited 'layer 2'6' a metal which does not participate in the electrochemical reactions and which makes contact with the electrode 27 is vaporized and is galvanically connected to the negative pole 30 of the element 10. The metal electrode 27 forms the negative one Anode.-of this element 10. A plastic line leads through the carrier 26 and the first electrode 27 37 containing the first electrolyte two chambers 36 'and 46> as shown / with one another connects.

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The container 16 as well as the carrier 26 take part in the electrochemical reactions

not part, so they are constantly inactive. The container and the plastic of the carrier 26 can for example Made of polyethylene, polypropylene, PVC or the like. Consist.

The space between the horizontal top of the partition 22 formed by the molecular sieve 23 'and the first electrode 27 is filled with a first liquid electrolyte 31, which is an aqueous metal salt solution, the metal of which is the metal or the main metal of the first electrode 27 corresponds. I.

The one between the two molecular sieves 23, 23 ' third electrolyte 24 of the partition wall 22 'is also an aqueous metal salt solution whose Acid residue is the acid residue in the first electrolyte

2Q '»31 dissolved metal salt can correspond. The second Electrolyte 25 can be an alkali, the alkali metal of which is the same as the metal in the third electrolyte dissolved metal salt can correspond. The alkali lye I is also an aqueous solution. The concen ~

trations of the in the three electrolytes 24, 25, 31 |

dissolved metal compounds are not critical, |

should, however, be matched to one another in such a way that none of the electrolytes has a tendency to become one To withdraw water to a disruptive extent from neighboring electrolytes, so that each electrolyte has the fills in the space assigned to it.

The volumes of the electrolytes 24, 25 and 31 remain essentially the same during charging and discharging. Under '

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Under certain circumstances, if the element 10 becomes overcharged, solvent can degrade electrolytically.

However, this can be seen from the increase in Ladeo

Detect voltage and, if necessary, ensure that charging is automatically terminated when the Increase in charging voltage indicates the risk of overcharging. Also other ways to -_ Avoidance of overloading exist.

The top and bottom of the ceiling 44 and the The uppermost chamber, which is bounded by the carrier 26, forms a compensation chamber 46 through which "'is ensured without any problems is that all electrolytes always fill the interior of the element 10 to the required extent by the equalization chamber 46 contains first electrolytes and the molecular sieves 23, 23 'for their water existing solvent are permeable.

20th

The two molecular sieves 23, 23 ′ of the dividing wall 22 are sealed on the peripheral wall of the container 16 attached, for example clamped in a manner not shown. The lower diaphragm 14 can be glued onto the perforated base 18, for example. The filter 15 is also on the peripheral wall of the container 16 sealed attached.

There is also a vent line 33 available, from the chamber 34 of the element 10 containing the second electrolyte 25 through the container peripheral wall through to the ceiling 44 to the outside leads to the discharge of oxygen produced in the second electrolyte 25 during charging, 35

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I. ₅ The layer 26 'consists of a metal that is not galvanic when the element 10 is charged and discharged

Tension to the perforated sheets 13,: 20 developed and therefore remains inactive. For example, it can be made of nickel and the two metallic

f 2.0 perforated sheets 13, 20 can then also expediently consist of% this metal, for example nickel

I exist »

!; In contrast, the metal of the first electrode 27 goes to

15 Discharge in solution until it is used up. ^D ^ ^e ξ layer 26. 'is unable to bring about an electricity delivery

I ren, so that the element 10 is then completely

; ';, load is. When reloading, the

'; first metal electrode 27 on metal layer 26 '

20 ^ ^{it from} carrier 26 again without dendrites being formed. The first metal electrode 27 which is forming again is also solid in itself and it is

There is no risk of metal breaking off

I from her.

I 25

1 The chamber containing the first electrolyte

'. 36 of the element in the chamber 4 6 leading line

can also be used to divert hydrogen, which occurs during charging in the first electrolyte tion remains unused, serve from the chamber 36.

It should be mentioned / that the molecular sieves 22, 23 'a

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5472 - 35 -

Ti'enngrert2e can / the oxygen-Mölekülfe (O ₂ ) lets through. Nevertheless, the oxygen that forms in the second electrolyte 25 during charging does not pass through the molecular sieve 23, but collects on it to form gas bubbles which can then escape to the outside through the vent line 33.

It should also be mentioned here that, for better discharge of the oxygen gas bubbles formed during charging in the second electrolyte and, if necessary, ^{the hydrogen gas bubbles formed in the} first electrolyte to the lines 33, 37, it can be expedient for the element 10 in the Operation is slightly inclined to the horizontal, which “can be achieved, for example, by slightly different heights of the feet 18 '. Or one can also provide that the partition 23 'and also the first electrode 27 with support 26 are inclined slightly to the horizontal and the other parts in the electrolyte, such as the molecular sieve 23, the diaphragm, etc., are aligned horizontally. If necessary, a slight curvature of the diaphragm 23 * and the first electrode 27 can also be provided, the vent lines 33, 37 then opening into the relevant chambers 36, 34 at the highest points of this curvature.

The mode of operation of this element is described using the following examined example: 35

• ■ · ι

I I I

I I <

I · ι 1 (M Il

ι ι · "·«

ι · 1 I I

I ι Ι

, 5472 - 36 -

The first electrode 27 consisted of the? Examination from zinc. The first electrolyte 31 consisted of aqueous zinc sulfate solution, pH value approx. 4-6 * The third electrolyte 24 consisted of aqueous calcium sulfate solution, pH value approx. 5-8. The second electrolyte 25 consisted of potassium hydroxide solution. The molecular sieves 23, 23 'each had a separation limit of 50, so that they could neither be used for zinc nor for SO. and KOH were permeable * In contrast, these molecular sieves are permeable to H, OH and H ₃ O * The third electrode and the perforated plate 13 consisted of nickel. -c When unloading the poles 19, 30 on the managerial ^one processing 40 and a load 41 connected to each other and then played the following operations when unloading from were:

A * ^{1 of} the ^{air cathode 11 beginning at the} diaphragm 14, the following reaction occurs in that air penetrates into it through the diaphragm 14:

2 H ₀ O + O ₀ + 4e ~ - »· 4 0H ~ The oxygen comes from the ambient air. The OH ions formed in this way migrate as charge carriers through the partition 22 into the first electrolyte 31 and the following reaction then takes place in it at the first electrode 27:

2 Zn + 4 OH "- ♦ 2 Zn (OH) ₀ + 4e ~

The zinc hydroxide Zn (OH) which formed was precipitated and sank onto the flat, horizontally oriented molecular sieve 23 ^! and deposited here in an even layer. Once all of the zinc '

5472 - 37 -

■ ■ · · t i · ί I

ι a I ι ι I I >

• lit ·· I ι ι ι t ι

of the first electrode 27 was consumed, this secondary element 10 was discharged.

After discharge, the member 10 has been loaded i by the positive pole of the charging voltage source to the Ladepol 21 and the negative pole has been the charging voltage source connected to the pole 30 in a manner not shown again. The charging voltage was approx. 1.8 V, whereby it should be mentioned that a voltage of approx. 1.2 to 1.3 V can easily be drawn from the element when it is discharged.

When charging, the following reaction takes place in the second electrolyte:

2 H ₀ O "4e ~ _ * ο t + 4 H ⁺

The third electrode 20 does not change.

The oxygen that is formed escapes through the vent line 33. The second Electrolyte 25 forming Η-ions migrate as charge carriers the third electrolyte 24 of the partition 22 and its molecular sieves 23, 23 'through into the first Electrolyte 31 and the following reaction takes place in it:

30th

Zn (OH) ₂ + 4 H ⁺ -r 2 Zn ⁺⁺ + 4 H., 0

The zinc ions released from the zinc hydroxide Zn (OH) _o turned out to be uniform,

massive zinc layer 27 on the metal layer 26'35

ii It ti I * t

«· ■» il · ι . ,. ι · ■> I .1

5472 - 38 -

I of the carrier 26 down. This created the first

I Electrode 27 again as solid / flat / when loading

ig g zirik layer of approximately the same thickness. It adheres to the * Trägerraetall very firm, can

So don't peel off. When the electrode 27 was re-formed, no dendrites were formed / so that a high number of charging and discharging cycles 10 can be achieved with this element 10.

It was found / that the potassium ions in the third electrolyte 24 ι neither during charging nor

\ when unloading, for the rest of the time by the

I _ 15 molecular sieve 23 passed though that

.; Separation limit was 50, so this molecular sieve 23 '

I as well as the molecular sieve 23 per se for potassium ^

1 ion was permeable. It can be assumed that this

I surprising effect is based on the fact that the potassium

'*. 20 ions in the third electrolyte 24 have no affinity for the acid in the first electrolyte 31 ^

'; left SO. had more because in the third electrical

lytes to the acid residues SO found in it. , were sufficiently firmly attached and these

j 25 bond K ₃ SO ₄ a molecular weight above the separation limit of the s-molecular sieve 23

.'f. of approximately 174 has. This thins the second

J and third electrolyte 25 and 24 are not irreversible.

I also found that self-discharge

30 öes secondary element 10 is extremely small, so that if no power is drawn, it will retain its charge for a very long time.

The mentioned separation limit of the molecular sieves 23, 23 ' 35 was smaller than the atomic weight of zinc and that

5472 - 39 -

• Molecular weight of SO, and of KQH so that they

neither zinc, nor the acid residue SO., nor potassium-5

let through hydroxide.

«I M rtii« ι> it If t

I Il I * * Il It *

ti ι I It

· Ίι

Claims (1)

Dr.-Ing. Dipl, Phya. OSCAR KING ' Approved representative at the Europälachen Pa: eatamt Telex: 07-22747 Koen Dtsi.iou.i. i ' -x-. , - Telephone: (07 U) 29 64 61 ^{Km; i0 N Γ ε} ' ^l · ^{; : c} Telegram: Koenlgpat 7000 STUTTGART-I, Klüpfelatraße 6 (BLZ. '*' ** ° " P.O. Box 61 5472 - 1 - Electrochemical element, which has a metallic first electrode, which forms its negative anode, and an electrolyte containing dissolved metal salt which reacts chemically with it during discharge having, wherein the metal of the dissolved metal salt corresponds to the metal of the first electrode, and further has a second electrode constituting the positive cathode which is a second electrolyte is assigned, which is separated from the first electrolyte by a porous partition, thereby characterized in that negative OH ions in the second electrolyte (25) when the element (10) is discharged are formed as charge carriers for which the partition (22) is permeable, and that the partition (22) as one the transfer of the metal and the acid residues of the metal salt dissolved in the first electrolyte (31) in the second electrolyte (25) preventing lock acts. 1 tii Uli ti - 2 - 2. Element according to claim 1, characterized / daö it is a rechargeable secondary element (10) and the partition (22) for during charging in the second electrolyte (25) forming, positively charged hydrogen ions is permeable, so that these can migrate into the first electrolyte (31). 3. Element according to claim 1, characterized in that it is a non-rechargeable primary element. 4. Element according to any one of the preceding claims, characterized in that the partition wall is a has the only molecular sieve whose separation limit is made so that it is suitable for the OH and for K ions and preferably also for the solvent, the electrolyte is permeable, but not for the other molecules contained in the second "electrolyte (25)". 5, element according to one of claims 1 to 3, characterized in that the partition (22) has two Molecular depths (23,23 ') between which there is a third electrolyte (24) such that the transfer of cations from the second electrolyte (25) is prevented in the first electrolyte (31) with the exception of hydrogen cations. ti Il IfM Il If I iii *. i ϊ t I * Il III * I * j «W ff * » t Ii 4lij «4 Ii Ii itt 4 '- 3 - 6. Element according to claim 5, characterized in that that the third electrolyte (24) contains dissolved metal salt, preferably alkali metal salt. 7. Element according to claim 6 _t, characterized in that that the acid residue of the metal salt dissolved in the third electrolyte (24) corresponds to the acid residue of the first Electrolyte (31) corresponds to dissolved metal salt * 8. Element according to claim 6 or 7, characterized in that that the metal of the metal salt dissolved in the third electrolyte (24) is the metal corresponds to a dissolved metal bond in the second electrolyte (25). 9. Element according to claim 6, 7 or 8, characterized in that that the acid residue of the metal salt of the third electrolyte (24) is one atomic weight above that Separation limit of the molecular structure separating the third electrolyte (24) from the second electrolyte (25) (23). 5472 10. Element according to one of the preceding claims, characterized in that the second electrode (11) is an oxygen cathode, preferably is a Lüftkatoce, which forms the positive pole (19) of the element (10) when discharging. 11th Element according to Claim 1o, characterized in that the second electrode (11) has activated carbon powder (12) as a catalyst. 12. Element according to claim 11, characterized in that the activated carbon (12) by a metal grid or the like (13) is contacted. 13. Element according to claim 11 or 12, characterized in that that it has a third electrode (20; which is connected to a positive Poles a charging current source serving to charge the element is used and that the third electrode outside the activated carbon powder (12) but still within the second electrolyte (25) is located. 14. Element according to claim 13, characterized in that that the activated carbon layer (12) by an impermeable to its activated carbon powder, however, for the second electrolyte (25) permeable filter (15) from the one above it Area of the second electrolyte, in which the third electrode (20) is located, is separated. I ί > I I - 5 - 15. Element according to any one of the preceding claims, characterized in that the second Electrolytes (25) are assigned a ventilation system (33) for oxygen that is formed during charging is. J ¹⁰
16. Element according to one of claims 1 to 9 / characterized in that the second electrode is also a metal electrode used in Discharge forms the positive pole. 17. Element according to any one of the preceding claims, characterized in that the second Electrolyte has a pH that is greater than 7. 20th .18. Element according to any one of the preceding claims, characterized in that the first electrolyte is a Entlüftungslextung (45) is assigned for those \ hydrogen which when in the Charging occurring in the first electrolyte chemical reduction remains unused. 19. Element according to one of the preceding claims, H characterized in that the first electrode (27) is an aluminum electrode. 35 It ·>> ι 5472 - 6 - Ψ 5 20. Element according to one of claims 1 to 18 / characterized in that the first electrode • i (27) is a zinc electrode * *: 21. element according to one of claims 1 to 18, I ¹⁰ characterized in that the first electrode I (27) is a magnesium electrode. ίί 22. Element according to one of the preceding claims, I characterized in that the first electrode -I ¹⁵ (27) small amounts of alkaline earth metal to- " I are alloyed and / or in the first electrolyte (31) \ before loading the element for the first time, a small I Amount of alkaline earth hydroxide, preferably calcium I contain hydroxide, which is the first time ■ ^ Charge dissolves in the first electrolyte and its Alkaline earth metal then attaches itself to the first electrode • (27) precipitates together with their main metal. 23. Element according to any one of the preceding claims, characterized in that the first electrolyte (31) exclusively or essentially only Contains metal ions that correspond to the metal of the metal salt dissolved in it. 30th 24. Element according to one of the preceding claims, characterized in that the first electrolyte (311 contains metal sulfate dissolved as the metal salt. 35 • · c ι - 7 - 25. Element according to any one of the preceding claims, characterized in that the first electrolyte contains dissolved metal nitrate as a metal salt. 26. Element according to any one of the preceding claims, characterized in that the first electrolyte (31) contains metal chloride dissolved as a metal salt. 27. Element according to any one of the preceding claims, characterized in that at least one Electrolyte is an aqueous solution. 28. Element according to claim 27, characterized in that the second electrolyte (25) is aqueous Alkali lye, which is preferably 20 to 45 Ge ψ contains weight percent alkali hydroxide. r 29. Element according to one of the preceding claims, | characterized in that its electrodes (11,27) jj and the partition (22 ) are arranged approximately flat and at a distance from one another and their operating positions are preferably approximately horizontal. 30. Element according to claim 29, characterized in that that the partition (22) is located vertically below the first electrode (27). i I ι ι - 8th - e, 31. Element according to one of the preceding claims, data characterized in that the solvents of the electrolytes (24,25,31) are the same chemical compound and the partition (22) is permeable to this solvent. 32. Element according to claim 28, characterized in that that the second electrolyte is potassium hydroxide and / or sodium hydroxide solution. 33. Element according to one of the preceding claims, * 5 characterized in that the first electrolyte (311 has a pH value of less than 7. 34. Element according to any one of claims 1 - 32, characterized in that the first electrolyte Ϊ " ⁶ ^ has a pH equal to or slightly greater than 7.