DE102009037144A1 - Contact element for electrically contacting e.g. lithium ion accumulator to store current in cell and to discharge current from cell, has low temperature co-fired ceramic layer formed on side of two-dimensional lattice structure - Google Patents

Abstract

The element has a chemically inert, electrically conductive layer (1) laminarly and electrically contacting an electrode (5) such as cathode or anode of an electro-chemical cell (4). The layer is utilized as a part of the electrode. A two-dimensional lattice structure (2) is formed on one of sides of the layer and consists of metal and/or alloy. A low temperature co-fired ceramic layer (3) is formed on a side of the lattice structure, where the side lies opposite to the layer. The layer contains carbon fibers, graphite powder, graphite fibers and/or carbon nano-tubes. An independent claim is also included for a method for manufacturing a contact element.

Description

The The present invention relates to a contact element for electrical Contacting a power-generating electrochemical cell, in particular a fuel cell, a rechargeable battery or a battery, for Recording an electric current from this cell and for discharging the flow out of the cell. The present invention relates about that addition to arrangements comprising at least one such contact element and such an electrochemical cell as well as to manufacturing processes for contact elements according to the invention and / or orders.

contact elements for electrically contacting electrochemical cells or Power collection elements are used in a variety of technical, electrochemical Cells used, such as in lithium-ion batteries or in PEM fuel cells. Technically unproblematic is here the use of gold layers as a current collector, contrary to However, in particular the high price of such full-area current collectors. Other metals can due to a passivation (eg aluminum) or corrosion (for example, steel, copper, silver, etc.) by the often strongly corrosive conditions are not or only conditionally used. Also, carbon-containing polymers (for example, by injection molding or hot stamping can be) known as current collecting elements. However, these have a lower conductivity and thereby limit the achievable power of the electricity generating electrochemical cell. Especially in the field of miniaturized electrochemical cells prevents the comparatively high ohmic Resistance of the carbonaceous layers the use as a current collecting or contact element.

The object of the present invention is therefore to provide a conductive contact element for electrically contacting a current-generating galvanic cell, which has a sufficiently high electrical conductivity, which is light, which is sufficiently resistant to corrosion and in particular also for use with miniaturized electrochemical cells suitable is. The object of the present invention is also the description of a manufacturing method for such a contact element. In the context of the following description, a miniaturized electrochemical cell is understood as meaning, in particular, an electrochemical cell having a surface area of 0.01 cm ² to 500 cm ² and a thickness (perpendicular to the effective areas of the cell) of 100 μm to 1 cm.

Under Chemically inert, the following property is understood below: A chemically inert layer dissolves in technically relevant periods under typical operating conditions only in the order of magnitude of a few percent in the electrolyte adjacent to the layer or the gaseous or liquid Fuel up. About that In addition, chemical inertness should also be understood here. that next to a directly adjacent layer also underneath Layers are not dissolved by the electrolyte.

These Objects are achieved by a contact element according to claim 1, by an arrangement according to claim 15 and solved by a manufacturing method according to claim 17. advantageous Embodiments of the contact element, the arrangement and / or The manufacturing process can be found in each case the dependent claims.

The The present invention will be first in general, then described in the form of an embodiment. It must in the embodiment in combination with each other realized features in the context of present invention (the scope of which is defined by the independent claims is not realized in the configuration shown be, but can also independent be realized from each other. In particular, therefore, in the context of by the claims Given scope of individual features shown in the embodiment also be omitted or otherwise with others combined individual features are combined.

Basic The idea of the present invention is to make the contact element multi-layered with an electrically conductive, electrically non-conductive or semiconducting carrier layer (hereinafter also referred to as third layer), one arranged thereon metal-based (ie at least one metal and / or an alloy containing) second layer and one on the second layer arranged protective and discharge layer (hereinafter also referred to as first layer), which is a chemically inert, electrically conductive Layer containing a carbon-containing polymer or It consists of doing, acting, realizing.

The carrier layer and the protective and discharge layer are advantageously over the entire surface educated. The sandwich layer between these two layers arranged second layer (metal-based layer) may be formed over the entire surface, but usually, it is advantageous, especially from an economic point of view, this layer is not over the entire surface, so for example as a network and / or lattice structure form.

The The present invention thus relates to metal- and carbon-containing (or carbonaceous) layers on an electrically conductive, nonconductive or semiconductive carrier substrate.

When support material or material for the third layer can also electrically conductive materials such as metals, modifications of carbon (graphite, glassy carbon) or electric conductive composites (in particular: carbon-containing polymers) be used.

The inventive multilayer Contact element can then be flat with an electrode (cathode or anode) of an electrochemical Cell are connected or adjacent to such an electrode to be ordered. Advantageously, both at the anode as well as at the cathode of the electrochemical cell contact elements according to the invention used.

alternative but it is also possible the protective and dissipation layer (first layer) itself as an electrode (or as part of an electrode) to an electrochemical cell use.

• 1. Von dem Elektrolyten sehr gut benetzt werden, d. h. je nach verwendetem Elektrolyten (wässrig oder nicht-wässrig) muss die Oberfläche der Carbonschicht hydrophil oder hydrophob gestaltet werden.
• 2. An die spezielle Grenzflächenreaktion angepasst sein. Der Ladungsdurchtritt hängt neben der Benetzung stark von der elektronischen Struktur der Carbonschicht ab. Oftmals kann die Oberfläche viel Polymere enthalten, welches bspw. durch Behandlung in wässrigen Säuren, Basen oder Salzlösungen, bevorzugt in wässrigen Basen entfernt werden kann, so dass die Carbonpartikel in direkten Kontakt zum Elektrolyten treten können.

If the carbon layer or the first layer is used as the electrode, it should have the lowest possible resistance to the electron passage through the boundary layer of carbon layer electrolyte. For this the carbon layer should:

• 1. Be very well wetted by the electrolyte, ie, depending on the electrolyte used (aqueous or non-aqueous), the surface of the carbon layer must be made hydrophilic or hydrophobic.
• 2. Be adapted to the specific interfacial reaction. The charge passage depends not only on the wetting but also on the electronic structure of the carbon layer. Often, the surface can contain a lot of polymers, which can be removed, for example, by treatment in aqueous acids, bases or salt solutions, preferably in aqueous bases, so that the carbon particles can come into direct contact with the electrolyte.

The Carbon contents of the carbon layer or the first layer should preferably be high to high conductivity but there must still be enough polymer for adhesion to the substrate and a completely covering layer too guarantee. The carbon pastes used for the production of carbon layers contain from 10 to 99 percent by weight carbon particles. Preferably, the carbon pastes contain 70-90 weight percent carbon particles.

the One skilled in the art is aware of how he produces such carbon pastes (the pastes are commercially available). Attention is with the Making the current collector that the electrode material or the electrode advantageous with the not yet cured carbonaceous Polymer is brought into contact. This stands by the thermal Annealing the carbon-containing polymer a very good conductive compound with a minimized contact resistance.

The electrical conductivity should be as high as possible. It is essential in the invention that the current flows only a very short path through the carbon layer and is then absorbed by the (very good conductive) metal structure (second layer). Therefore, it is also possible to use less conductive carbon layers, which may have higher chemical inertness. Typical resistances of carbon paste are 1-100 Ω □ at layer thicknesses of 10-25 μm (which corresponds to resistivities of 10 × 10 ^-6 to 2500 × 10 ^-6 Ωm).

The Chemical inertness results from the low interaction of the chosen Paste material or the later Carbon layer with the electrolyte or the reactants (fuel). In the case of an acidic, aqueous Electrolytes (typical of a PEM fuel cell) the polymer should not contain hydrolyzable functional groups (eg polyester, polyamide). A high resistance against acidic aqueous phases have thermoplastics such. As polypropylene or polyvinylidene fluoride on.

The contact element according to the invention thus consists of the combination of at least one metal-containing layer with at least one carbon-containing polymer layer. The metal-containing layer can be applied over the entire area, but is preferably applied to the carrier substrate in a non-full-area coverage, preferably in the form of a grid. The carbon-containing polymer layer is advantageously full-surface is applied, whereby then a uniform decrease in the current from each point at the power-generating interface to the electrode of the electrochemical cell or to the actual electrochemical cell is ensured. The dissipation of the electric current from the electrochemical cell thus takes place through the suitably formed carbon-containing polymer layer (first layer), via the second layer (eg grid) and via external conductors that are in electrical contact with the second layer. The dissipation of the current is thus realized via the metal-based second layer under the carbon-containing polymer layer.

The second layer is advantageously based on electrically high conductive Metals (eg gold, copper, silver, nickel, aluminum etc.), which are preferably applied in lattice form on the carrier substrate. The metal-containing second layer can thereby taking into account of the chosen carrier substrate can be built from different starting materials: so can metal-containing Polymers are used to form the second layer. in the Case of ceramic carrier substrates can metal-containing thick-film pastes and / or metal-containing inks for Production of the metallic lattice structure can be used.

The Metal-containing polymers are preferred on substrates printed circuit board technology (PCB). These are epoxy resins, Phenolic resins with reinforcement through paper or fiberglass fabric.

The metallic constituents of the second layer can also be in the form of metal powder, Balls or platelets be educated.

The carbon-containing polymers or carbon-containing polymers of the first Layer can by filling of polymers with carbon fibers, graphite powders, graphite fibers, carbon blacks and / or Carbon nanotubes ("carbon nano tubes ") will be realized.

The carbon-containing polymer layer or first layer does not take in particular only an electrical line, but also a sealing function (Corrosion protection for the metallic second layer and for the underlying carrier substrate).

Not only for but the first layer containing the carbonaceous polymers also (in the case of using metal-containing polymers) for the second Layer can any polymers are used, for example, resins of various chemical composition (epoxy resin, polyester resin, ...) and under UV radiation curing or thermosetting Polymers.

The The above-described first and second layers can be almost arbitrary Carrier substrates or third Layers are realized: Particularly advantageous are ceramic Materials (such as high temperature fired ceramics, So HTCC ceramics or low-temperature fired ceramics, ie LTCC ceramics), Plastics such as polyimides (eg in film form) or semiconductors like silicon. It can also metals and electrically conductive substrates such as graphite or carbonaceous composites are used.

The Coating of the carrier substrate with the second layer and the subsequent application of the protective and Ableitschicht or first layer on the composite of the second and third layer can with a variety of coating methods (in particular by printing process): screen printing, roller printing (English: roll coating), mask printing, aerosol printing, inkjet printing, gravure printing, Pad printing, and / or dispensing printing; all these printing methods are possible. It is essential that the second and the third layer as separate layers on the carrier layer applied or applied.

For the production the corrosion resistant Protective layer (first layer), In addition to the above-mentioned (printing) procedures, the following procedures can be used: spin coating, painting or spray painting.

The Protection and dissipation layer (first layer) is preferred with the aforementioned method applied or spin coating, varnishing or spray painting. The mentioned printing or coating methods usually require different rheological and thermal Properties of the carbon-containing polymers.

The contacting of the protective and discharge layer (first layer) to the electrode or to the (solid state) electrolyte can be done by mechanical fixation of the components and pressing and bonding at high pressures. Preferably, the electrode or the (solid state) electrolyte is brought into contact with the not yet cured carbon layer, so that the viscous carbon layer intimately with the electro connect the denmaterial and the thermal annealing results in a particularly conductive connection with a low contact resistance.

The Contact element is thus constructed according to the invention in layers; With the layer application can (especially with respect to the second layer) also a geometric structuring by the local application take place (so the second layer in the form of interconnected Conductor tracks and / or grid structures are applied, as well it is basically also possible, to structure the protective layer appropriately).

By suitable design of the carrier substrate (eg foil or thin Ceramic layer), the applied second layer and the applied, polymer-based protective and Ableitschicht can realize very thin contact elements which have a total layer thickness of all three layers of 50 μm and below can have. It can planar contact elements as well as curved (eg cylindrical) contact elements will be realized.

The can be described contact elements are preferably used in PEM fuel cells, as they do without further Modification can be used.

The leaves described contact element when selecting a suitable (chemically resistant) polymer also for the methanol fuel cell, the phosphoric acid fuel cell or the use alkaline fuel cell. The polymer may be in the Fuel (methanol) or the electrolyte (aqueous potassium hydroxide or Phosphoric acid) do not dissolve.

The following 1 shows an example of a contact element according to the invention in a cross section perpendicular to the layer plane of the individual layers or to the active surfaces of the electrochemical cell connected to the contact element.

On a carrier substrate in the form of an LTCC ceramic 3 became a two-dimensional lattice structure by one of the above-described printing methods and based on a conductive ink 2 applied. This two-dimensional lattice structure 2 (from which in the figure, the cross sections through the grid lines in one of the two spatial directions can be seen) was after its application to the carrier layer or third layer 3 by means of a printing or coating process (screen printing, roller printing, aerosol printing, mask printing ink jet printing, pad printing, dispenser printing, spin coating, painting, spray painting) with a carbon nanotube-filled, ie carbon-containing polymer layer covered (first layer 1 ).

The layer system thus produced from the three directly adjacent layers 1 to 3 was then after its preparation at the surface of the first layer 1 with an electrode 5 a fuel cell 4 connected. The connection of the shift system 1 to 3 with the electrode 5 can be done by stacking, pressing and mechanical fixation or gluing. The layer 1 is z. B. in the liquid state on the carrier 3 respectively. 2 and 3 and is then preferably cured by a thermal treatment at up to 170 ° C. It is possible the electrode 5 or the on layer 3 adjacent layer 5 already in the still liquid layer 3 immerse and then perform the annealing process. This increases the mechanical connection of the layer 1 and layer 5 and it reduces the electrical contact resistance.

The layer thickness d3 of the carrier substrate layer 3 here is about 100 microns, the layer thickness d2 of the grid lines and the second layer is d2 = 12 microns and the layer thickness of the protective and dissipation layer 1 (Layer thickness d1 from the top of the lattice structure 2 to the interface with the fuel cell 4 or their electrode 5 ) is d1 = 25 microns.

An essential point of the present example (and the present invention) is the use of a non-conductive carrier substrate 3 in that the carbon-based polymer layer 1 alone (due to its small thickness of here 25 microns, but this can also be reduced to, for example, 10 microns) is not able to produce sufficient electrical conductivity. Therefore, between the carbon-based polymer layer 1 and the non-conductive support 3 the structured grid metal layer 2 educated. In combination with the carbon-based polymer layer, it is then sufficient not to form this layer over the entire surface but in a structured manner, which has economic advantages, in particular when using precious metals. Because the carbon-based polymer layer 1 has a comparatively small thickness d1, the current path through this (comparatively poorly conductive) layer is sufficiently low, so that the corresponding power losses are minimal.

The minimum thickness d1 of the carbon-based polymer layer 1 results from their function as a corrosion layer for the underlying, buried second metal-based layer 2 , The thickness d1 must be at least so great that a tightness of the layer 1 with respect to the corresponding reactants (gases or liquids) of the electrochemical cell is ensured.

Based on a 1 According to the invention carried out contact element could be shown that with a silver-containing, 12 micron high lattice structure under a 25 micron thick, fully applied carboniferous polymer layer, a lower total resistance (11.3 mΩ) compared to a full-area gold-containing current derivative (17.6 mΩ) achieved can be. Structure 1 Resistance R [mΩ] Proportion of % Structure 2 Resistance R [mΩ] Proportion of % Au layer 17.6 100 C layer 1.8 15.9 total 17.6 100 Ag Network 9.5 84.1 total 11.3 100

The The table above shows that only a small proportion of the total resistance exceeds the carbon-based polymer layer falls off. Because the electricity is only one short path through the significantly worse conductive carbon layer needed results in the low total resistance.

The table thus shows a comparison of the total resistances of a contact element from a full-surface, gold-containing coating on the above-described carrier substrate and a contact element of a silver mesh and a carbon-containing polymer layer on this carrier substrate. The dimensions of the contact elements in the layer plane were 19 × 23 mm ² , the spacing of adjacent grid lines in the rectangular silver grid was 1.4 mm (for the 19 mm long side) and 1.6 mm (for the 23 mm long side), the middle one Cross section of a grating line of the silver grating was 200 μm in width and 12 μm in height.

The materials used had the following resistivities: gold layer according to the prior art ρ = 6 × 10 ^-8 Ωm, silver layer: ρ = 2.97 × 10 ^-8 μm, carbon-containing polymer layer: ρ = 4.5 × 10 ^-4 μm ,

• • Mittels des vorbeschriebenen Konstruktionsschemas lassen sich dünne, stabile und kostengünstige, jedoch dennoch elektrisch gut leitfähige Kontaktelemente ausbilden.
• • Im Gegensatz zu einer vollflächigen Kontaktierung mit einem Edelmetall wie Gold werden deutlich verringerter Mengen eines elektrochemisch unedleren und günstigeren Metalls (z. B. Silber) zur Kontaktierung benötigt. Es ergeben sich somit verringerte Materialkosten.
• • Die flächige Abdeckung der metallhaltigen Struktur zur Stromableitung durch die kohlenstoffhaltige bzw. karbonbasierte Polymerschicht kann einer Korrosion des verwendeten Metalls vorbeugen. Hierdurch können neben Silber auch unedle Metalle (beispielsweise Kupfer) verwendet werden, wodurch die Materialkosten weiter verringert werden, ohne dass die Funktion der Stromableitung an der elektrochemischen Zelle beeinträchtigt wird.
• • Für elektrochemische Zellen, die bisher ausschließlich über karbonhaltige Polymere kontaktiert wurden, ergibt sich eine deutliche Verbesserung der Leitfähigkeit bei der Stromabnahme. Für bisher durch Metallgitter kontaktierte Elektroden kommt es zu einer Absenkung des Kontaktwiderstandes zwischen dem Kontaktelement und der Zellelektrode, da die dünnen Schichten der karbonhaltigen Polymere eine größere Oberfläche aufweisen.

Compared with the contact elements known from the prior art, the contact elements according to the invention thus have a number of significant advantages:

• • By means of the above-described design scheme, thin, stable and cost-effective, but still highly electrically conductive contact elements can be formed.
• • In contrast to a full-surface contact with a precious metal such as gold, significantly reduced amounts of an electrochemically less noble and cheaper metal (eg silver) are required for contacting. This results in reduced material costs.
• The areal coverage of the metal-containing structure for current discharge through the carbon-based or carbon-based polymer layer can prevent corrosion of the metal used. As a result, in addition to silver and base metals (such as copper) can be used, whereby the material costs are further reduced, without the function of the current dissipation is impaired at the electrochemical cell.
• • For electrochemical cells, which were previously contacted exclusively by carbon-containing polymers, there is a significant improvement in the conductivity during current collection. For previously contacted by metal mesh electrodes there is a reduction of the contact resistance between the contact element and the cell electrode, since the thin layers of the carbonaceous polymers have a larger surface area.

Claims (21)

Contact element for electrically contacting a current-generating electrochemical cell ( 4 ), for receiving an electrical current from the cell and for discharging this current from the cell, comprising: a chemically inert, electrically conductive first layer ( 1 ), which contains or consists of a carbon-containing polymer, with which a planar electrical contact to an electrode ( 5 ), ie to the cathode or to the anode, of an electrochemical cell ( 4 ) and / or that as at least a part of an electrode ( 5 ) an electrochemical cell ( 4 ), a second layer ( 2 ) on the side of the first layer ( 1 ), on which the electrical contact to the electrode ( 5 ), opposite side of the first layer ( 1 ) and / or on the cell-remote side of the first layer ( 1 ) and contains or consists of a metal and / or an alloy, and a third layer ( 3 ) on the first layer ( 1 ) opposite side of the second layer ( 2 ) is arranged. Contact element according to the preceding claim, characterized in that the third layer ( 3 ) contains or consists of an electrically conductive, an electrically non-conductive or a semiconducting and / or a chemically inert material. Contact element according to one of the preceding claims, characterized in that the first layer ( 1 ) contains a thermoset, a thermoplastic and / or a resin, in particular an epoxy resin, and / or a composite material of at least one of the aforementioned materials. Contact element according to one of the preceding claims, characterized in that the first layer ( 1 ) Contains carbon fibers, graphite powder, graphite fibers, carbon black and / or carbon nanotubes. Contact element according to the two preceding claims characterized characterized in that the carbon fibers, the graphite powder, the Graphite fibers, the carbon black and / or the carbon nanotubes even within thermoset, thermoplastic, resin and / or composite is distributed / are. Contact element according to one of the preceding claims, characterized in that the second layer ( 2 ) seen in its layer plane is not formed over the entire surface and / or structured, in particular two-dimensionally structured, and / or as a grid and / or network structure, in particular as a regular and / or rectangular or square grid and / or network structure is formed. Contact element according to one of the preceding claims, with the exception of the immediately preceding claim, characterized in that the second layer ( 2 ) is formed over its entire surface seen in its layer plane. Contact element according to one of the preceding claims, characterized in that the first layer ( 1 ) and / or the third layer ( 3 ) seen in their respective layer plane is formed over the entire surface / are. Contact element according to one of the preceding claims, characterized in that the second layer ( 2 ) one on the first layer ( 1 ) and / or the third layer ( 3 ) is printed layer. Contact element according to one of the preceding claims, characterized in that the second layer ( 2 ) Contains or consists of Cu, Ag, Ni, Al and / or Au and / or an Ag-Pd alloy and / or that the metal and / or the alloy in the second layer ( 2 ) in the form of powder, spheres, platelets and / or metal-containing polymers is / are. Contact element according to one of the preceding claims, characterized in that the third layer ( 3 ) a resin, a plastic, in particular in the form of a plastic film, a ceramic and / or silicon, in particular a polyimide, a phenolic resin, an epoxy resin, a silicone resin, a polyester resin, a low-temperature fired ceramic and / or a high-temperature penetration Contains or consists of ceramic. Contact element according to one of the preceding claims, characterized in that for the layer thickness d1 of the first layer ( 1 ): 1 μm ≤ d1 ≤ 250 μm, preferably 10 μm ≤ d1 ≤ 50 μm; and / or that for the layer thickness d2 of the second layer ( 2 ): 1 μm ≤ d2 ≤ 100 μm, preferably 5 μm ≤ d2 ≤ 25 μm; and / or that for the layer thickness d3 of the third layer ( 3 ): 50 μm ≤ d3 ≤ 4000 μm, preferably 100 μm ≤ d3 ≤ 500 μm. Contact element according to one of the preceding claims, characterized in that the first, the second and the third layer ( 1 . 2 . 3 ) form a layer system of three stacked, directly and flat adjoining layers. Contact element according to one of the preceding claims characterized characterized in that the electrochemical cell is a galvanic Cell, in particular a fuel cell, preferably a PEM fuel cell, a battery, in particular a redox battery or a rechargeable battery, in particular a lithium-ion accumulator, is. Arrangement comprising an electrochemical cell ( 3 ), in particular a fuel cell, a battery, in particular a redox battery or a rechargeable battery, and at least one contact element according to one of the preceding claims, wherein with the first layer ( 1 ) of the contact element, a planar electrical contact to an electrode ( 5 ) of the electrochemical cell ( 4 ) and / or wherein the first layer ( 1 ) of the contact element as at least a part of one of the electrodes ( 5 ) of the electrochemical cell ( 4 ) is trained. Arrangement according to the preceding claim marked by two contact elements according to one of the preceding contact element claims, in which with the first layer of the first contact element, a planar electrical Contact is formed to the anode of the electrochemical cell and / or wherein this first layer is formed as at least a part of this anode is and wherein with the first layer of the second contact element a plane formed electrical contact to the cathode of the electrochemical cell is and / or wherein this first layer as at least a part of this Cathode is formed. Manufacturing method for a contact element for electrically contacting a current-generating electrochemical cell ( 4 ), for receiving an electrical current from the cell and for discharging this current from the cell, comprising the steps of providing an electrically nonconductive or semiconductive and preferably also chemically inert carrier layer ( 3 ), imprinting a second layer containing or consisting of a metal and / or an alloy ( 2 ) on the top of the carrier layer ( 3 ), applying a chemically inert, electrically conductive, a carbonaceous polymer-containing or consisting of protective layer and protective layer ( 1 ), if the second layer ( 2 ) over the entire surface of the top of the carrier layer ( 3 ) was printed on the carrier layer ( 3 ) facing away from the second layer ( 2 ), or, if the second layer ( 2 ) not on the entire surface on the top of the carrier layer ( 3 ) was printed on the exposed top portions of the carrier layer ( 3 ) and on top of the layer ( 2 ). Production method according to the preceding method claim characterized in that a contact element and / or an arrangement according to one of the preceding device claims. Manufacturing method according to one of the preceding method claims, characterized in that the printing of the second layer ( 2 ) is carried out by screen printing, gravure printing, inkjet printing, pad printing, dispenser printing, aerosol printing, mask printing or by roller coating. Manufacturing method according to one of the preceding method claims, characterized in that the printing of the second layer ( 2 ) is performed using an electrically conductive thick film paste or an electrically conductive ink. Manufacturing method according to one of the preceding method claims characterized in that with the second layer facing away from the surface of the protective and discharge layer ( 1 ) a planar electrical contact to an electrode ( 5 ), ie to the cathode or to the anode, of an electrochemical cell ( 4 ) and / or that the protective and dissipation layer ( 1 ) is formed so as to be at least part of an electrode ( 5 ) an electrochemical cell ( 4 ) is usable.

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