DE3125525A1 - Solid-electrolyte body - Google Patents

Abstract

A solid electrolyte (1) for electrochemical cells consists of an only single-layered layer of particles of an ion-conducting solid electrolyte powder and of a curable industrial resin (3) as a binder which fills the gaps between the densely packed solid electrolyte particles (2) which extend from layer surface to layer surface. To prepare the layer, particles are used from a sieve fraction whose size exceeds the intended layer thickness by approximately 1.3 times. As a result of the fully cured casting-resin embedment being ground down subsequently, all the particles receive fresh facets (4) which ensure good electronic contact with the cathode or anode material to be applied subsequently. <IMAGE>

Description

Solid electrolyte body

The invention relates to a solid electrolyte for an electrochemical Cell in the form of a thin layer.

Solid-state electrochemical cells are preferred in sandwich construction manufactured in such a way that cathode, solid electrolyte and anode in tablet form one form a cylindrical stack. In the course of the advancing miniaturization of solid-state cells, For example, for use in electronic wristwatches, the aim is to this development trend with ever flatter components or

to adapt to thinner tablets or discs.

The manufacture of the solid electrolyte tablets is particularly important here Trouble. The usual procedures, namely the sintering of finely ground solid electrolyte powder into a ceramic body or the shaping of Powder compacts and re-sintering fail below a critical layer thickness, because the molding can no longer properly detach from the tool or crumble. The cutting out of thin slices from a solid solid electrolyte body, e.g. a single crystal, on the other hand, can only be achieved with a great deal of technical effort.

The invention is therefore based on the object for miniaturized Solid-state cells make an extremely thin-layer solid electrolyte body available make the similar demands in terms of dimensional accuracy and strength as inclined for larger solid tablets.

The object is achieved in that it consists of a Ion-conductive solid electrolyte powder and a binder is made, with the size of the individual solid electrolyte particles is dimensioned so that each particle is continuous extends from one surface of the layer to the other surface It lies in the frame the invention that the solid electrolyte depending on the structural conditions of the Cell can be shaped in many ways, usually as disks or platelets, at times but also as a cup or vessel. It is essential that the layer thickness of the general flat solid electrolyte body is very small and only a few tenths Millimeters.

The structure of the solid electrolyte body is based on its Production process described. This takes place in such a way that a polycrystalline, powdery solid electrolyte material initially a sieve fraction with a very narrow grain spectrum wins. The average grain size of the solid electrolyte powder should be be about 30% larger than the desired thickness of the solid layer to be produced.

The powder is mixed with a binder that is used during processing is liquid and hardens later. Hardenable technical resins are used as binders such as unsaturated polyesters, epoxy resins or crosslinkable hydrocarbon casting resins in question.

Many of these types of resins are used in metallography as embedding media used or form the basis of two-component adhesives. Condition for the The only purpose of the invention is that the binder is alkali-resistant.

The amount of binder should be such that, if possible, in one dense single layer of solid electrolyte particles between all spaces the particles are filled and each powder particle with its neighboring Powder particles are bound by the binder.

The mixture is now spread on a surface that is not with the Binder glued together so that the particles of the solid electrolyte form a single layer form, allow to harden and punch a disc of the desired size. the end. the Solid electrolyte particles now touch both surfaces of the pane, but are still largely enveloped by the binder at this stage, so that the exposed portion of the solid electrolyte in the surface, based on the The amount of binder in the surface is very small.

The conductivity across the wafer is correspondingly low.

The solid electrolyte can now be exposed to a greater extent, that one grinds the surfaces by about 15% of the total thickness of the disc.

Figure 1 shows a thin-layer solid electrolyte according to the invention on average.

Like the natural dimensions of the disk I shown here 10 mm in diameter and 0.2 mm in thickness. The original thickness of the Disc as well as the contours of the solid electrolyte particles 2 are before grinding shown in dashed lines.

The solid electrolyte particles 2, their original size in the sieve fraction has fluctuated by about 0.26 mm, are as dense as possible in the single layer packed while the binding agent 3 fills the gaps in the packing exactly. The fresh Ground surfaces 4 of the electrolyte particles 2 make one in this way considerable part of the disc surfaces and thus ensure a good electronic contact with the cathode or anode tablet to be applied. But above all, each individual grain makes by moving from surface to surface extends across the disc, one unobstructed and one relatively large Line cross-section favored ion transport possible.

The embedding of the solid electrolyte particles in the synthetic resin binder also gives the finished molded body a certain ductility, which makes it is advantageous from a comparable sintered ceramic product that is brittle is different.

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Claims (3)

Claims 1! Solid electrolyte for an electrochemical cell in the form of a thin layer, characterized in that it consists of an ion-conducting Solid electrolyte powder and a binder is made, the size of each Solid electrolyte particle is dimensioned so that each particle is continuously from one surface of the layer extends to the other surface. 2. Solid electrolyte according to claim 1, characterized in that the Binder is a curable engineering resin. 3. A method for producing a solid electrolyte according to the claims 1 and 2, characterized in that an ion-conducting solid electrolyte powder a sieve fraction is provided, the grain size spectrum of which is within very narrow limits by about 1.3 times the amount of the layer thickness desired for the solid electrolyte body fluctuates that the sieve fraction mixed with hardenable binder on one Pad is spread out to a single-layer particle layer that after Curing of the binding agent. Punched out platelets of the desired shape and size and that the surfaces of the platelet on each side by about 15% of the platelet thickness be sanded off.