Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0561—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of inorganic materials only
  • H01M10/0563—Liquid materials, e.g. for Li-SOCl2 cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/665—Composites
  • H01M4/667—Composites in the form of layers, e.g. coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/028—Positive electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/002—Inorganic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/36—Selection of substances as active materials, active masses, active liquids
  • H01M4/48—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides
  • H01M4/485—Selection of substances as active materials, active masses, active liquids of inorganic oxides or hydroxides of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/661—Metal or alloys, e.g. alloy coatings
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/66—Selection of materials
  • H01M4/663—Selection of materials containing carbon or carbonaceous materials as conductive part, e.g. graphite, carbon fibres
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/64—Carriers or collectors
  • H01M4/70—Carriers or collectors characterised by shape or form
  • H01M4/80—Porous plates, e.g. sintered carriers
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T29/00—Metal working
  • Y10T29/10—Battery-grid making

Definitions

• Rechargeable battery cell that can be operated at normal temperature
• the invention relates to a rechargeable battery cell that can be operated at normal temperature and has an electrolyte system based on SO 2 .
• the electrolyte system of rechargeable battery cells usually contains a salt, the ions of which form the charge carriers of the electrolytic line (conductive salt) and a transport medium which ensures the required mobility of the ions of the conductive salt in the electrolyte system.
• the invention is particularly directed to cells whose electrolyte system contains a conductive salt that contains halide ions. Chloride-containing conductive salts are particularly common.
• the transport medium which ensures the required mobility of the ions of the conductive salt in the electrolyte system, is often organic (as is usual in particular with lithium-ion cells).
• the invention relates specifically to cells in which the electrolyte system is based on sulfur dioxide.
• S0 2 rendes electrolyte system (S0 2 -based electrolyte system) "are systems in which the mobility of the ions of the conductive salt is at least partially guaranteed by the S0 2 ', S0 2 is therefore a functionally essential component of the transport medium of the electrolyte system.
• S0 2 electrolyte system suitable with the present invention is described in German patent application 10110716.1, filed on March 7, 2001 or the corresponding international patent application PCT / DE02 / 00789.
• a fundamental problem with rechargeable batteries is their limited lifespan. Therefore, an important goal of battery development is to develop batteries that are available for as large a number of charge and discharge cycles as possible without their usable capacity decreasing significantly. This property is commonly referred to as cycle stability.
• the capacity and thus the usability of rechargeable batteries does not only deteriorate due to repeated charging and discharging, but also if the battery is stored in an unused state. This problem is particularly pronounced in the case of the lithium-ion cells that have recently become more common, particularly for portable telephones and video cameras, the capacity of which has usually decreased significantly after just one year.
• the internal resistance of the cell is another parameter that deteriorates over the course of the battery life.
• the increase in internal resistance means that the maximum current that can be drawn decreases or the battery voltage assumes inadmissibly low values when connecting relatively low-resistance consumers.
• the active material when the batteries are in operation, the active material can disintegrate into relatively small, mechanically non-interconnected particles which detach from the electrode surface and are therefore no longer available for the electrochemical process required to operate the battery cell.
• the electrical or electrochemical connection of parts of the active material to one of the electrode conductor elements can be lost.
• the mechanical connection between the electrode discharge element and the active mass can be lost, so that the active mass falls off the discharge element.
• the object of the invention is to achieve an increase in the service life of rechargeable battery cells with an electrolyte system based on SO 2 .
• a battery cell in which an electronically conductive discharge element of at least one electrode in a surface layer serves as a reaction protection material to protect the discharge element against undesired reactions, an alloy of chromium with another metal and / or a protection metal selected from the Group consisting of rhodium, tungsten, rhenium, tantalum, platinum, iridium, osmium and technetium in pure form, as a component of an alloy or as a component of a compound and / or a carbide, nitride or phosphide of titanium, nickel, cobalt, molybdenum , Contains iron, vanadium, zircon or manganese.
• an electronically conductive discharge element of at least one electrode in a surface layer serves as a reaction protection material to protect the discharge element against undesired reactions
• an alloy of chromium with another metal and / or a protection metal selected from the Group consisting of rhodium, tungsten, rhenium, tantalum
• the discharge element is the part of the electrodes of battery cells that is usually made of metal and serves to enable the required electronically conductive connection.
• the discharge element is in contact with an active material which is involved in the electrode reaction of the respective electrode and which can in principle be solid, gaseous or liquid.
• the electrode reaction with the participation of the active material leads to the formation or consumption of free electrons, which are discharged via the discharge element during discharge (negative electrode) or supplied (positive electrode).
• the discharge element consists of a metal (for example nickel, cobalt, copper, stainless steel or aluminum).
• Discharge elements made of carbon or conductive plastics are also used.
• Use- Surface structures with a very large surface area compared to their thickness are preferred, with perforated structures (grids, perforated sheets) and in particular highly porous materials such as expanded metals or metal foam materials being preferred.
• a particulate active material can be mixed with a suitable binder (e.g. polytetrafluoroethylene) and connected to the discharge element by pressing (see U.S. Patent 5,213,914).
• a suitable binder e.g. polytetrafluoroethylene
• methods are also known in which the required connection of the active material to the discharge element is produced without the use of organic binders (cf. US Pat. No. 5,656,391).
• the invention is partly based on a proposal published in 1990 in US Pat. No. 4,892,796. It describes an alkali metal cell with an electrolyte based on S0 2 and a CuCl 2 cathode.
• the lead element of the cathode referred to there as the “current collector”, contains a chromium foil plated onto a nickel core.
• the chrome foil is preferably applied to the nickel core by hard chrome plating in a thickness of 2.5 ⁇ m to 50 ⁇ m (0.1 to 2 mil). This is intended to inactivate the surface of the current collector. It is reported that the battery capacity of the cells remains largely stable over a larger number of charge and discharge cycles when the cathode drain element is coated with the chrome foil.
• Chromium diffusion layer within which the concentration of chromium decreases in the direction leading away from the surface.
• this additional chrome layer is not a relatively thick hard chrome layer, but rather a very thin shiny chrome layer (decorative plate) with a layer thickness of less than 5 ⁇ m, preferably at most 2.5 ⁇ m and particularly preferably at most 1 ⁇ m.
• a protective metal selected from rhodium, tungsten,
• C a carbide, nitride or phosphide of titanium, nickel, cobalt, molybdenum, iron, vanadium, zircon or manganese.
• reaction protection materials can also be combined with one another.
• surface layer is not to be understood as restrictive in that it must be a discrete layer with a homogeneous composition.
• a lot of- This term more specifically denotes that region of the discharge element which is close to the surface and which determines its reaction behavior (in particular with regard to reactions with the electrolyte) and in which at least one of the reaction protection materials mentioned must be localized in order to achieve the desired protective effect.
• the surface layer is defined by the
• the measures according to the invention achieve a substantial improvement in the life of the battery cells.
• the invention is of very special importance in connection with cells which reach very high cell voltages (more than 4 volts) during charging. This applies in particular to lithium cells. Overcharge reactions can take place in such cells at relatively high charging voltages, which are very advantageous for the function of the cell. Further details are described in international patent application WO 00/79631 AI. However, according to the inventors' findings, the high cell voltages of more than 5 volts associated with these advantageous overcharging reactions lead to reaction conditions with regard to the discharge element of the positive electrode, which are particularly problematic (for example because of the formation of reactive chlorine).
• the present invention makes it possible to charge these cells in the above-mentioned high potential range without impairing their service life. It is therefore particularly in connection with the battery cell described in WO 00/79631 AI applicable.
• the content of this publication is made by reference to the content of the present application.
• Another advantage of the invention is the increased mechanical resilience (especially compared to US Pat. No. 4,892,796).
• the invention is particularly directed to cells whose negative electrode contains an active metal A in the charged state, which is selected from the group consisting of the alkali metals, the alkaline earth metals and the metals of the second subgroup of the periodic table.
• active metals are lithium, sodium, calcium and zinc.
• alkali metal cells whose active metal preferably sodium and particularly preferably lithium are distinguished by particularly advantageous for practical application properties, especially .a low weight and - in conjunction with conventional appropriate positive electrodes - a high 'cell voltage (hence a very high Energy density), off.
• the high cell voltage leads to the special corrosion problems mentioned.
• the reaction protection material is present in a surface layer of the discharge element.
• the inside of the discharge element can. consist of another material, which is referred to below as the core material. Materials based on nickel, copper, stainless steel, aluminum or carbon are suitable, for example.
• a relatively thin surface layer is sufficient, which preferably encloses the entire surface of the discharge element that is in contact with the electrolyte system. loading it should preferably be designed such that it is impermeable to the components of the electrolyte system (in particular halide ions contained therein).
• a few atomic layers are sufficient, depending on the reaction protective material used, so that it may suffice if the protective protective material is present on the surface in a layer thickness of 0.5 nm.
• a somewhat larger layer thickness of at least 10 nm, preferably at least 100 nm and particularly preferably at least 0.5 ⁇ m is advantageous.
• the protective metals can be contained in the surface layer in pure form, as a component of an alloy or as a component of a compound.
• alloys of the protective metals with one another and with other metals are suitable.
• a particularly advantageous protective effect has been observed for a surface layer which is an oxide of one of the named
• Carbides, nitrides and phosphides of the protective metals or the compounds of the reaction protection material type C can be used as further examples of compounds.
• the surface layer consists entirely of one or more of the reaction protection materials of types B and C mentioned.
• the content of reaction protection materials of these types should in any case be higher than 20 mol%.
• reaction protection material The choice of a suitable manufacturing process depends on the choice of the reaction protection material. Provided that a galvanic separation of the reaction protective material is possible, this method is open to the invention 'suitability net.
• the used for the reaction protection material of type A Chromium that is used can be applied well to a conductor element, the interior of which consists of a different metal, in particular nickel, using galvanic chromium plating methods which are customary for other purposes.
• galvanic order is also possible for rhodium and platinum, although these materials are currently less preferred due to their high price.
• reaction protection materials mentioned cannot be applied or can be applied only with great difficulty in a thin surface layer on a core material. They are preferably used in constructions in which the discharge element consists entirely (ie not only of its surface layer) of a uniform material (for example one of the protective metals). In many cases, however, such materials, in particular protective metals of type B, can also be used to produce thin layers by means of deposition from the gas phase (for example by sputtering). A surface layer with a type A reaction protection material can also be advantageously produced in this way.
• the manufacturing process includes a step in which a sheet Ableitelementmaterial containing at least on its surface already chromium or one of the protective metals of type B, is additionally annealed in a preferably inert or reducing gas atmosphere.
• a chromium diffusion layer can also be produced in another way, for example by depositing chromium on the surface of the diverter element material by a method associated with heating the surface, in particular by sputtering. The chromium atoms diffuse into the surface without the need for special annealing.
• the above-mentioned formation of the oxide of the protective metal in the reducing atmosphere should be due to the fact that nickel oxide present on the surface of the nickel material is reacted with the chromium (with reduction to metallic nickel) to form chromium oxide. It is particularly surprising that the formation of a metal oxide Layer, which in its pure form is less conductive than the pure metal, does not contribute to deterioration, but rather improves the properties of the discharge element.
• the desired protective reaction effect can also be achieved by tempering an alloy containing one of the metals mentioned at elevated temperature in order to increase the concentration of the metal on the surface by the heat treatment process to such an extent that a sufficient protective effect is ensured.
• a metal composite can be produced mechanically.
• a surface layer containing a reaction protection material which contains an organic or inorganic binder, to the core material by means of the binder in such a way that a protective layer having the properties required in the context of the present invention is formed.
• the discharge element with the surface layer containing the reaction protection material is preferably used for the positive electrode of the cell because, according to the inventors' observations, the risk here is more disruptive Surface reactions due to the electrochemical conditions prevailing at the positive electrode is particularly large. However, it can also make sense to provide the negative electrode discharge element with a surface layer that contains one of the reaction protection materials mentioned. For example, it has been observed that in batteries consisting of several cells, when the cells are charged together in a series connection, operating states can occur in which a disturbing surface reaction takes place predominantly on the positive electrode on the negative electrode lead-off element in a manner similar to what is otherwise the case.
• the positive electrode of which is a composite electrode, in which - as described above - the conductor element forms a substrate for an active mass firmly connected to it.
• An intercalation compound consisting of an alkali metal (as active metal A of the cell), a transition metal M with the atomic number 22 to 28 and oxygen is particularly preferred.
• the alkali metal is preferably lithium.
• cobalt and nickel are particularly preferred.
• Binary and ternary metal-oxide intercalation compounds which contain two or three different transition metals in the lattice structure, such as, for example, lithium-nickel-cobalt oxide (cf.
• FIG. 2 shows a cyclic voltamogram when using a deflecting element, in the surface layer of which rhodium is contained; 3 shows a cyclic voltamogram when using a discharge element with a chromium diffusion layer; 4 shows a cyclic voltamogram when using a tungsten conductor element; Fig. 5 shows the course of the discharge capacity and the internal resistance depending on the number of
• FIG. 6 shows the variation of the discharge capacity and the internal resistance as a function of the number of charge and discharge cycles at a Inventions' proper cell according to the prior art
• 7 shows an EDX line scan of a surface cross section of a diverter element with an electroplated chrome plating
• 8 shows an EDX line scan of a surface cross section of a diverter element with a chromium diffusion layer.
• the effect of the invention was examined with the aid of cyclic voltamograms.
• a three-electrode arrangement with lithium as the reference and counter electrode and the respective investigated discharge element as the working electrode was used.
• the test cell was filled with an electrolyte system that contained iAlCl4 as a conducting salt and • S0 2 as a transport medium (in a ratio of 1: 1.5).
• the potential was between 3.5 volts and 5.5 volts vs. Li / Li + varies with a potential forward speed of 20 mV / s.
• Figure 1 shows a cyclic voltamogram when using a diverter element of untreated nickel '.
• Curve A shows the first cycle in which a current flows from about 5 volts, which is caused by a reaction on the surface of the discharge element.
• B the current flow is considerably lower because a disturbing reaction (according to the inventors' knowledge, above all a formation of nickel chloride) has taken place on the surface of the discharge element. The surface layer thus formed prevents the desired overloading reaction.
• Curve C shows the fifth cycle in which practically no current flows.
• FIG. 2 shows a cyclic voltamogram with a diverting element based on a nickel sheet, which was galvanically coated with a protective layer of rhodium approximately 2 ⁇ m thick.
• the thick curve A is the voltamogram of the first cycle
• the thin curve B is the voltamogram of the hundredth cycle. It can be clearly seen that the two cycles practically do not differ. From this result it can be deduced that the desired overloading reaction takes place in practically unchanged form even after several hundred cycles.
• FIG. 3 shows corresponding results for a discharge element based on a nickel sheet, on which chromium was first deposited galvanically with a thickness of approx. 0.5 ⁇ m (bright chrome plating). The discharge element was then heated under protective gas with slightly reducing properties (argon / hydrogen) to 800 ° C within about six hours, this temperature a Held for an hour and then cooled. The figure shows the first cycle (thin line A) and the three hundredth cycle (thick line B). Here, too, there is almost complete agreement, ie the surface properties of the diverter element have remained practically unchanged over the three hundred cycles.
• FIG. 4 shows a corresponding test result for a diverter element, which overall consists of a uniform material, in the case shown of solid tungsten.
• the voltamogram of the first cycle is shown as a thick curve A, the hundredth cycle as a thin curve B.
• the result shows that even massive metals, e.g. Tungsten, can be used as a conductor element, the electrochemical properties of which remain stable. In this case, the reaction current not only does not decrease after more than a hundred cycles, but actually increases.
• FIGS. 5 and 6 show the typical course of the discharge capacity C (curve A in each case) and the internal resistance R (curve B in each case) as a function of the number n of charge and discharge cycles.
• FIG. 5 shows that, in the case of cells designed according to the prior art, the capacity initially remains largely stable, but then rapidly drops to values at which the cell is practically no longer usable. The resistance increases accordingly. This rapid deterioration in the Zeil parameters can be explained by the fact that the increase in resistance leads to an increase in the necessary charging voltage, which in turn leads to an increase in disturbing surface reactions of the discharge element.
• FIG. 6 shows that this effect does not occur with a cell designed according to the invention and both the capacity and the internal resistance remain largely stable over a large number of cycles.
• the EDX line scans shown in FIGS. 7 and 8 show the distribution of the metals chromium (Cr) and nickel (Ni) and the content of oxygen atoms (O) i in the surface layer of a discharge element.
• the concentration is plotted in arbitrary units depending on the depth below the surface in ⁇ m, the zero point of the abscissa being chosen arbitrarily.
• the carbon concentration (C) also shown is due to the fact that epoxy resin was used to embed the investigated fine sanding.
• FIG. 7 shows that an electroplated chrome plating creates a discrete chrome layer which is practically completely separated from the nickel base material.
• the slight overlap of the curves is due to the limited depth resolution of the investigation method (spot width approx. 1 ⁇ m).
• a look at the cross section in a scanning electron microscope shows that the galvanic bright chrome plating is not crack-free, but has cracks that extend to the nickel base material. _.
• FIG. 8 shows the corresponding results after the material has been annealed (as described in connection with FIG. 3).
• the result is a transition region that is several ⁇ m wide, in which the concentration of chromium gradually decreases away from the surface and the concentration of nickel increases accordingly.
• the layer thickness of the chromium has decreased significantly due to the material migrating into the chromium diffusion layer, but the cracks are largely closed.
• the experimental results presented illustrate a total that one, excellent improving the quality of electrochemical 'cells can be achieved with a bright chrome, as has been commonly used for decorative purposes only, if the surface layer of the discharge is generated, a chromium diffusion layer •.
• the surface layer which is effective to protect against unwanted reactions, is only a few ⁇ m thick.
• the invention can therefore be used particularly advantageously in the above-mentioned discharge elements made of highly porous materials such as expanded metals and in particular metal foams, in which the reaction-protecting surface layer not only protects the outer surface, but the entire inner surface of the porous material.

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• 2001
  • 2001-06-15 DE DE10128970A patent/DE10128970A1/de not_active Withdrawn
• 2002
  • 2002-06-10 AU AU2002316775A patent/AU2002316775A1/en not_active Abandoned
  • 2002-06-10 JP JP2003506031A patent/JP4518791B2/ja not_active Expired - Fee Related
  • 2002-06-10 EP EP02745133A patent/EP1415359A2/de not_active Withdrawn
  • 2002-06-10 WO PCT/DE2002/002112 patent/WO2002103827A2/de not_active Ceased
  • 2002-06-10 US US10/480,489 patent/US7244530B2/en not_active Expired - Fee Related
  • 2002-06-10 DE DE10292678T patent/DE10292678D2/de not_active Withdrawn - After Issue

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