DE2627143A1 - SEPARATOR FOR ELECTROCHEMICAL CELLS - Google Patents

Description

PATENT Attorney DIPL.-ING. H. STROHSCHÄNK 8000 MÜNCHEN 60 MUSÄUSSTRASSE 5 TELEPHONE (08 fl) 88 1608

1G.6.1976-33 (4) 290-14421

> on 14

Sepiv.-ator for electrochemical cells

-de Srfindun ;; ui refers to a Jeparabor l'ür elelctroc he ».lic ·, before cells; with a riepar ^ tor disc, which on both Sides with opposite in the electrochemical ropes LlektroGen is provided over'.ih? .Enden ^ stand elements.

I-'ieparaborai for accumulators and other electrochemical cells' ./erden often see with ab st and β elements in the form of bands ve ", which allow a julecbrolyte circulation and a gas extraction without disturbing the support function of the separator ο -in such separs From the point of view of the flow, the gate can be viewed as a bundle of channels combined in parallel let non-uniform flow distribution in ülektroIyträum, in ier at vSystemen with circumferential Slektro- LYTEN in the ^ RAXIS hardly ever a homogeneous distribution of iilektrolytstromes dor in the inlet region cells over the entire .querschnitt reach. Furthermore remain Crasblasen in the electrolyte _r space, uie beispielsv / otherwise they come from a line electrode in a metal / air cell, sf. '. ndig in an and the same xi-snal and ''"block i-.uf this way the passage of the electric current; set; it is in the form of stripes, -like 3chv / ierigke.iten

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or gob η even if the spacing elements of the separators -; ls special cords'or as specially shaped 'it I'ta trained on' ./or .-. en.

An anucre type of structural elements is known from 3./-AÜ 550 655, in which separator disks with an almost punctiform character, so-called fixed heels, are described, and are connected to a flexible separator sheet. Jiüse -.bsütze are arranged offset from one another on the two ueiteii of Separ-.torbluütes in such ..eise, to di.S ^ e ^ di.ue ratorblatt between adjacent electrodes entgegen- ^ caetzter ola;? Itut, where the ZXI ->. bs ^ sets alternating to .ril ::. ge koi'imen, v. 'shaped like a curve, whereby between each side of the separator blade and the electrode K-Jiüla opposite it stand for the slectrolvt circulation. The separator - '.. ^ ducation ernä & s of 3w ^r -AS 350 655 therefore aims to create channels au, through the lülektrol ^ t z v, ^r een cen electrodes Liann circulate rapidly through the. The above-mentioned divergence cannot be remedied in this way, however, there is often a non-uniform flow pattern in the electrolyte space, since no mass transport can develop between the channels obtained in the manner described. In addition, there is a great reduction in the use of solid heels due to the fact that they considerably increase the resistance in the electrolyte space.

The invention is based on the object of a separator of the type mentioned at the beginning in such a way - that he is without impermissible Resists, and increases a uniform flow rate. division in the electrolyte space is able to provide »

The task set -.-.- is achieved according to the invention by that as spacers vei'tikal and horizontal from each other separate raised portions of the separator disk are provided

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are that these raised areas run on both of the separator disc face each other at least partially and a curse of between 10 and 90% of the total Make up the separator surface, there is each of these raised Parts of one of the thickness of the separator disk at least equal Height above the separator disk is the largest dimension each of the raised areas is at least equal to the thickness of the separator disk, that is the garnet dimension of the separator disk in the vertical and in the horizontal direction is at most twenty times the thickness of the slice and that the smallest distance between two raised parts reaches at least the entire Sep-ratordickness.

The invention leads to a separator of a novel shape, which generates a uniform flow pattern in the entire electrolyte space, but is able to fulfill its supporting function to the fullest _o

Thanks to the new separator construction with raised parts, which are vertically and horizontally separated from each other and each other on both sides of the separator disc at least are partially opposite, the above-mentioned channel formation remains avoided. When equipping electrochemical cells with a separator designed according to the invention, the Electrolyte compartment functionally rather than having a single channel a homogeneous electrolyte flow over the entire cross-section, the average electrolyte velocity at the outer parts of the separator is therefore the same as the electrolyte velocity in the middle of the separator. The at least partially opposite position of the raised areas on both The sides of the separator disk are mutual as such position of these parts to understand that these parts overlap each other to such an extent that the elec Pressures exerted on the separator trap the separator disk can not deform, whereby a successive coupling of liquid and grass flows in a sideways direction.

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could be prevented. .! Be a preferred embodiment according to the invention, the raised areas are completely opposite one another on both sides of the separator disk, and in general it does not present any difficulty to the person skilled in the art, proceeding from the general information given above Teach the exact position of the raised areas on both sides of the separator disc for each individual application to be determined.

The mutual coupling of the positive and gas flows in a sideways direction can be made by a suitable position of the raised areas on both sides of the separator disc and through a suitable construction of these parts. According to a preferred embodiment of the invention these raised portions are arranged to force an upward flow into a zigzag flow path to follow, which can be achieved, for example, that the raised parts of the separator disc at Viewed from the top are arranged offset relative to one another or have different shapes. In another preferred embodiment of the invention the surfaces of the raised parts, through which the coupling paths result in the sideways direction, run under a certain angle to the horizontal plane, so that in contact Gas bubbles standing with these surfaces can easily move upwards. As suitable forms for the raised parts of the separator disk are, for example, the rice shape, the oval shape and the triangular shape with the tip of the triangle pointing downwards, but there are also all other types of polygon shapes in question, which result in a certain angle with the horizontal plane.

Decisive factors for the lateral deflection of the

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- and gas streams are, moreover, as the preceding description will be immediately clear, the wages of the raised parts and the smallest distance between adjacent such parts, io should, in order to achieve an immeasurably rapid discharge to be reached by gas bubbles from the electrolyte compartment, at least the height of the raised areas above the separator disk equal to their - ^ icke, while the upper limit is not critical for this height. usually this leaves Height in a range between 0.1 and 2.0 mm, preferably in a range between 0.2 and 1.0 mm, and in particular in a range between 0.3 and 0.6 mm. The shortest distance between two adjacent raised areas should be at least equal to the total thickness of the separator, i.e. the sum of the Thickness of the separator disc and the height of the raised areas be cUr separator disc on both sides, which size at the same time also represents the thickness of the sheet metal space, Practical values for this distance are in a range between 2 and 20 mm, preferably in a range between 3 and 10 mm, and in particular in a range between 4 and 8 mm.

The most important characteristic of a separator designed according to the invention is that the raised parts of the separator disk make up between 10 and 90 / ° of the entire separator surface. This measure simultaneously ensures that the desired flow distribution is generated and that the specified distances between the adjacent electrodes are maintained in a sufficiently reliable manner. A preferred range for the dimensioning of the surface of the raised parts of the separator disk is between 20 and 50> £, whereby particularly favorable results can be achieved for a range between 25 and 40 i * »

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The desired spacing also depends on the largest dimension of each raised section in the vertical and horizontal directions on the separator disk. This discharge should be chosen in such a way that these "dimensions" lie in a range between one and twenty times the thickness of the separator disk. This is generally synonymous with sizes from 2 to 20 mm. A preferred range is between 3 and 10 mm and in particular between A and 8 mm.

The above description of the invention shows that a further essential characteristic of a separator designed according to the invention is that the spacer elements are raised parts of the separator disk, which means that they actually form a rope of the separator itself. Since the separators in electrochemical cells ^{lie m} current paths between their two electrodes, it is necessary for the separator, including the electrolyte contained therein, to have the lowest possible electrical resistance. By designing the spacer elements as parts of the separator itself, a very low electrical resistance can be obtained for the separator, since the raised parts of the separator disk, which form the spacer elements, also absorb electrolyte, and at the same time this results in a Electrolyte reserve evenly distributed over the entire electrolyte space, which in turn ensures that the electrochemical punctures run very smoothly throughout the cell.

Most of the separator materials heretofore used for electrochemical cells also turn out to be useful for the production of separators in accordance with the invention Execution. However, for the purposes of the invention, these materials should be porous and at the same time

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gen be stable. These porous materials should also have good absorbency for the absorption of electrolyte and at the same time are resistant to corrosive agents Be agents as they exist in the electrolyte space and as they are for example from the combined effect of oxygen evolution, comparatively high temperature of a strongly alkaline electrolyte and the presence of catalytic active metals. All of these features together characterize the environmental conditions in the electrolyte compartment Metal / air battery. In principle, the material for the separator must be selected according to the type of electrochemical cell for which the respective separator is intended.

According to a preferred embodiment of the invention, a separator designed according to the invention can have a porosity in a range between 50 and 95 ° β> , which results in a good combination of dimensional stability and absorbency will be explained in detail below, the stated degree of porosity for the separator material relates to its state before embossing, in other words, to the porosity in the raised parts of the separator. As a result of the embossing, the material of the separator disk itself assumes a lower porosity than the raised parts. This lower degree of porosity can in some cases be less than $ 50. The porosity of the starting material used for the embossing should not be less than $ 50, otherwise the porosity in the actual disc body could become too low. On the other hand, a porosity of more than $ 95> may lead to inadequate stability with regard to compliance with the specified dimensions.

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Furthermore, the separators can be made from natural or synthetic polymers or from completely inorganic material such as asbestos, and yerbundra materials can also be used, with inorganic separators, for example, which consist of resistant minerals and oxides, which are supported by a stable Polymer like I-olyphenylene oxide (PPO) are held together. A useful natural polymer is, for example, wood, which has been used as a separator material in 31ei / 3-acid accumulators from the very beginning. Before the above description can be clearly recognized, a separator designed according to the invention must have considerable dimensional stability. Acidic materials, much more filthy or non-woven polypropylene, regenerated cellulose and derglo are therefore not particularly suitable for the presentation of the separators according to the invention. Dimensional stability results primarily from an isotropic structure of the separator. Fibrous materials are therefore only those in which the individual fibers have a good bond with one another, for example natural wood or in the case of the above-mentioned inorganic separators with, for example, asbestos as a filler from J.dl. In other fillings, such as, for example, glass fibers or other fibers, the shape stability must, so to speak, be incorporated into the interior, by defining the shape, for example, by adding large amounts of curable or vulcanizable resins. Separators, the porosity of which has been created with the help of so-called expansion means, such as the IPaIl in the case of microporous polyvinyl chloride, show good dimensional stability due to their isotropic structure and the pores in the separator material are largely spherical. However, its good dimensional stability can also be obtained with the aid of a material that is inherently dimensionally stable and exhibits good olfactory properties, as is often the case for polymers.

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According to a "preferred embodiment of the invention can through the separators. Embossing, for example, produced by separators of the type customary up to now. This Embossing also leads to a considerable improvement in the : - .; llgenie properties of the separator compared to the • ep-irators so far more common ..rt · So v / ground the mechanical Properties of the separators by the one produced by the embossing Stiffening improves, and most importantly, decreases the level of gas and liquid flows is considerable., while at the same time in the above, one Ye r evenly ·; inclination of the 3trö-nun ^ s picture results. The improved mechanical Sigcnschaftoii ("he show jeprajteri separators see especially in ^ orin an increased service life. 'Surprisingly crv / e ice - has shown itself -vusserdera, dasr ·; the olektriache In spite of the Zorapriüiiarun ^ the i-Iaterif-il only stood in vcrnachläöiji ^ bar small! lasse influenced xri.rd.

The separators designed according to the invention can be ciUGser-dem "iit i; ilfe mech .- .. ni3chur procedure> .vie 'ichnitt, a method v / ie. they .rUr. Sep? Xrators v.us porous wood before- 0U '.; T is, or can be made into a matrix or form, a method,. There are many, separators of the so-called inorganic 'Jyps "to the .nv / ending kournt» Ijin advantage of these raeohanicchen ii; r3tellungsv / ei '; en, v; ie cutting or casting »lies in that the raised parts of the separators are exactly the same The same two characteristics: they receive most of the remaining parts of the separators.

the separators made of pasern with a vulcanizing bear as 3indemit v / earthed, so they can be made by! reason ο ^. ^ v embossing in the ^ ev / ün. ciite «όγβι ge br ac lib become, \ / or .-. On the obtained structure d'-jin can be determined by hardening the ii-xraes.

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In the drawing, the invention is more preferred by hand Exemplary embodiments illustrated; show it:

1 shows a separator designed according to the invention in

a front view,

FIG. 2 shows a section through the illustration in FIG. 1 along the section line II-II in FIG. 1, 3 shows a detail shown on a larger scale

from Fig. 2,

4 shows a second exemplary embodiment for a separator designed according to the invention in a front view, Fig. 5 to 9 examples of different embodiments

of raised parts of the separator disk and FIG. 10 shows a section through the illustration of FIG. 7 the section line X-X in Fig. 7; 11 shows the arrangement of separators designed according to the invention in an electrochemical battery.

The separator shown in Fig. 1 has a separator disk 1 which is provided with raised portions 2 of circular shape. These parts 2 are each seen from the top of the disk 1 on straight lines. The largest dimension of the raised parts 2 in the vertical and horizontal directions is denoted by a .. in FIG. 1, while the smallest distance between two adjacent raised parts 2 is denoted by b. wearing. The resulting flow pattern for the electrolyte along the disk 1 is indicated in FIG. 1 by arrows. If gas bubbles 3 should block the flow path at one point, the flow looks for its way to the side into the free space 4 between the raised parts 2, as is also indicated in FIG. 1 by arrows.

The location of the raised areas 2 on both sides of the

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Disc 1, which in the example shown each other perfectly are opposite, can be seen from Fig. 2, while the representation in Fig. 3 in the form of further dimensions Definitions for the height h of the raised parts 2 above the pane 1 and the thickness t of the pane 1 brings.

The illustration in FIG. 4 shows a separator with raised portions 5 of triangular shape on a separator disk 6, the raised portions 5 being offset from one another when viewed from the top of the disk 6 appear. This arrangement of the raised parts 5 results in an upward flow being forced to Tracking a zxckzagformxgen flow path. The largest The dimensions of the raised parts 5 in the vertical and horizontal directions on the disc 6 are denoted by a "in FIG. 4, while the smallest distance between two adjacent raised parts 5 is designated b “.

The illustrations in FIGS. 5 to 9 show examples of various useful shapes for the raised areas, where these are diamond-shaped in FIG. 6, oval in FIG. 6 and in FIG. 7th 0 with! are. In Fig. 3, several circular raised portions are arranged in the form of a triangle next to one another, and 9 shows a hexagon obtained in an analogous manner. In FIG. 10, the embodiment of FIG. 7 is in cross-section shown, whereby the sloping edge areas are recognizable.

In the embodiment shown in Fig. 11 are Separators according to the invention built into a metal / air battery with a circulating electrolyte. The battery has metal anodes 7 and air cathodes 8. The air cathodes 3 are supplied with air via special air spaces 9. Between Metal anodes 7 and the air cathodes 8 are separators 10

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arranged, which act as flow distributors. From a storage container 11 becomes!. "Electrolyte by a pump 1 2 to a The inlet channel 13 is pumped and from there via distribution channels 14 forwarded to the individual ropes of the battery. The separators 10 exercise a dual function in that on the one hand, the electrolyte in the electrolyte spaces between the metallic anodes 7 and the air cathodes 8 uniformly Distribute over the entire electrode surface and help others to dissipate while the battery is charging wrapped * gas facilitate. The electrolyte comes out of the individual Ropes off the battery at overflows 15 and then returns to the reservoir 11 while the charge gases are up can escape from the ropes.

In order to better illustrate the advantages that can be achieved by the invention, two examples of its use will now be given of separators designed according to the invention in metal / air batteries and the experimental results obtained to be discribed.

example 1

A separator of the type illustrated in Figures 1 and 2 was made by embossing microporous polyvinyl chloride, with the raised parts making up 32% of the total surface and the remaining 68% of 0.7

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0.2 mm thick grain or iiai place v / urden. Measurements of the jider rate ύΑϋχβΐΐ separator before and after the embossing resulted in an increase of nuj? uen r & ktor C, 46 after pressing, which in view of the strong compression 'Is uber.casch.end is to be called small * ·

'Example 2 ■ ■

■ Λη according to Pig's cough. The embossed separator 1 and 2 were compared to a conventional, non-embossed separator, and it turned out that the maximum charging current in the embossed embodiment of the separator compared to the previously usual one. Factor 2 could be increased, which is mainly due to the improved gas flow.

Notwithstanding the description '-' of the invention in connection with Metal / liUft batteries eats the bins of those designed according to the invention Separators do not; limited to such batberies, Rather, these separators can be used in all types of electrochemical Use cells that contain separators, as is the case with lead / acid batteries, for example, with alkaline batteries Batteries, fuel cells and the like. Is the case. .Neither The choice of materials, the construction of the raised parts or the discovery of a custom, manufacturing method for the design of the separators offers for the expert starting any of the above description of specific cases Trouble.

Claims

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Claims (1)

Patent to the test (T.) Se Separator for electrochemical cells -with a separator disk which is provided on both sides with spacing elements which touch electrodes opposite in the electrochemical cells, characterized in that raised parts (2; 5) of the separator disk (1j 6 ) it is provided that these raised parts on both sides of the separator disk are at least partially opposite one another and make up a total area of zv / ischen 10 and 90 ρ of the entire separator surface, that each of these raised parts is at least the same height as the thickness (t) of the separator disk ( h) above the separator disk, has that the largest dimension (a ^ ja ₂ ) of each of the raised areas is at least equal to the thickness of the separator disk, that the largest dimension of the separator disk in the vertical and horizontal direction is at most twenty "before the disk thickness and that the smallest distance C b ₁ ; b ₂ ) reaches at least the entire separator thickness between two adjacent raised parts. 2. Separator according to claim 1, characterized in that _t the raised parts distributed over the separator disc are arranged. That for an upward flow of a flow path extending ziekzackförmig results. . _: 3. Separator. According to claim 2 ,. . there. du; rch characterized in that the raised parts of the separator disk are arranged offset relative to one another when viewed from above. _-::,: ■. ..-.- ■ -. 609882/1045 4. Separator according to one of claims 1 to 3, characterized in that the surfaces of the raised parts, along which there is a sideways derivation, an angle with the horizontal form. 5. Separator according to claim 4 »characterized that the raised areas are circular or oval, 6. Separator according to claim 4, characterized that the raised · ^ artia a polygonal Shape like in particular a triangular, a diamond-shaped one or have a hexagonal shape, 7. Separator according to one of claims 1 to 6, characterized in that the raised parts in have sloping edges in the vertical direction. 8. Separator according to one of claims 1 to 7 »dadur.ch characterized in that the height of the raised parts is in a range between 0.1 and 2.0 mm, preferably is in a range between 0 »2 and 1.0 mm and in particular in a range between 0.3 and 0.6 mm. 9. Separator according to one of claims 1 to 8, characterized in that the smallest distance between two adjacent raised parts is in a range between 2 and 20 mm, preferably in a range between 3 and 10 mm and in particular in a range between 4 and 8 mm - lies ο 10. Separator according to one of claims 1 .to 9, characterized marked that the raised parts 609882/1045 2627U3 Fine surface area from 2o to 50 -j, preferably from 10 to 45, J dor res harvest separately or ο bor flat out. 11 ο separator according to one of claims 1 to 10, characterized by the ;; the sublime. I have a maximum dimension in vertical and in have horizontal direction on the separator, within a .Bbereich between twice and twenty times due to the thickness of the disk. 12. Separator according to claim 11, characterized that the largest dimension of the raised areas in the vertical and in the horizontal direction on the Ceparator disc in a range between 2 and 20 mm, preferably in a range between 3 and 10 mm and in particular in. a range between 4 and 8 mm. 13. Separator according to one of claims 1 to 12, characterized in that it is made of a porous material with a porosity in a range between 50 and 95 ° . 14, separator according to claim 13, characterized that it has been preserved by embossing. 609882/1045