MXPA06004114A - Electrolyte capacitors having a polymeric outer layer and process for their production - Google Patents

Abstract

The invention relates to a process for the production of electrolyte capacitors having a low equivalent series resistance and low residual current, and which comprise a solid electrolyte of conductive polymers and an outer layer comprising conductive polymers applied in the form of a dispersion. Electrolyte capacitors produce d by this process and the use of such electrolyte capacitors are also provided.

Description

ELECTROLYTIC CAPACITORS THAT HAVE POLYMER EXTERIOR LAYER AND PROCESS FOR THEIR PRODUCTION FIELD OF THE INVENTION The invention relates to a process for the production of electrolytic capacitors having a low resistance in equivalent series and low residual current, which comprise a solid electrolyte of conductive polymers and an outer layer comprising conductive polymers, with the electrolytic capacitors produced by this process and with the use of these electrolytic capacitors. BACKGROUND OF THE INVENTION A solid electrolytic capacitor commercially available as a rule comprises a porous metal electrode, an oxide layer on the metal surface, an electrically conductive solid which is incorporated within the porous structure, an outer (contact) electrode, as, for example, a layer of silver, and other electrical contacts and an encapsulation. Examples of solid electrolytic capacitors are tantalum, aluminum, niobium, and niobium oxide capacitors with complexes with charge transfer, or solid electrolytes of pyrolusite or polymer. The use of porous bodies has the advantage that due to the large surface area it can achieve a very high capacitance density, that is, a high electrical capacitance can be achieved over a small space. The p-conjugated polymers are particularly suitable as solid electrolytes due to their high electrical conductivity. The p-conjugated polymers also called conductive polymers or synthetic metals. These are increasingly gaining economic importance, since polymers have advantages over other metals with respect to the ease of processing, weight and adjustment of the properties required by means of chemical modification.

Examples of known conjugated polymers-p are polypyrroles, polythiophenes, polyanilines, polyacetylenes, polyphenylenes and poly (p-phenylene-vinylenes), a particularly important polythiophene that is used industrially is poly-3, 4- (ethylene-1, 2 -dioxy) thiophene, often called poly (3, 4-ethylenedioxythiophene), since it has a very high conductivity in its oxidized form. The technological development in electronic components increasingly requires solid electrolytic capacitors that have very low equivalent series resistance (ESR). The reasons for this are, for example, the variable logic voltages, a higher integration density and the increase of the cycle frequencies in the integrated circuits. In addition, a low ESR also decreases energy consumption, which is particularly advantageous for uses operated with mobile batteries. Therefore, there is a desire to reduce the ESR of solid electrolytic capacitors to as low a value as possible. European Patent Specification EP-A-340 512 describes the preparation of a solid electrolyte of 3,4-ethylene-1,2-dioxythiophene and the use of its cationic polymer, prepared by oxidative polymerization, as a solid electrolyte in capacitors electrolytic Poly (3,4-ethylenedioxythiophene), as a substitute for manganese dioxide or charge transfer complexes in solid electrolytic capacitors, decreases the equivalent series resistance of the capacitor due to the higher electrical conductivity, and improves the frequency properties . In addition, modern solid electrolytic capacitors with low ESR require a low residual current and good stability towards external stress. During the production process, the high mechanical stress is increased during the encapsulation of the anodes of the capacitor, which can greatly increase the residual current of the anode of the capacitor. The stability towards the stress and therefore a low residual current can be achieved mainly by an outer layer with approximately 5-50 μm thickness of conductive polymers on the anode of the capacitor. This layer serves as a mechanical buffer between the anode of the capacitor and the contact on the cathode side. This prevents, eg, the silver (contact) layer comes into direct contact with the dielectric or this low mechanical stress is damaged, and as a result the residual current of the capacitor is increased. The conductive polymeric outer layer itself must have the so-called self-healing properties: relatively minor defects in the dielectric on the surface of the outer anode which increases despite the damping action are electrically isolated in this the conductivity of the layer outside in the defect is destroyed by the electric current. The formation of a thick polymeric outer layer by in situ polymerization is very difficult. In this context, the formation of the layer requires many coating cycles. Due to the high number of coating cycles, the outer layer becomes inhomogeneous, in particular the edges of the anode of the capacitor are often inadequately covered. Japanese Patent Application JP-A 2003-188052 reports that a homogeneous coating of the edges requires high cost coordination of process parameters. However, this makes the production process very susceptible to malfunction. In addition to the binder materials to accumulate the layers faster, it is also difficult, since the binder materials prevent oxidation polymerization in situ. In addition, the in situ polymerized layer as a rule must be free of residual salts by washing, as a result of which the orifices in the polymer layer are increased. A dense electrically conductive outer layer with good edge coverage can be achieved by electrochemical polymerization. However, the electrochemical polymerization requires the initial deposition of a conductive film on the insulating oxide layer of the anode of the capacitor and then the electrical connection of this layer is made for each of the individual capacitors. This embodiment of the contact is very expensive for mass production and can damage the oxide layer. The use of formulations comprising the powder of a conductive polymer and binder has, due to the high high-contact resistances between the individual powder particles, a very high electrical resistance for a possible production of solid electrolytic capacitors having a low ESR. In Japanese Patent Applications JP-A 2001-102255 and JP-A 2001-060535, a layer of polyethylenedioxythiophene / polystyrenesulfonic acid (PEDT / PSS), also called polyethylenedioxythiophene / polystyrenesulfonic acid complex or PEDT / PSS, for the protection of the oxide film and better adhesion of the solid electrolyte to the oxide film. The outer layer is then applied to this layer by means of in situ polymerization or by impregnation of the anode of the capacitor with the solution of the tetracyanoquinodimethane salt. However, this method has the disadvantage that the PEDT / PSS complex does not penetrate into the bodies of the porous anode having small pores. As a result, highly porous modern anode materials can not be used. US 6,001,281 describes, in the examples, capacitors having a solid electrolyte of polyethylendioxythiophene (PEDT) prepared in situ and an outer layer of the PEDT / PSS complex. An advantage of these capacitors, however, is that they have a high ESR of 130 mO and higher. In the still unpublished German Patent Application DE-A-10349112, a polymeric outer layer is produced by the application of a dispersion comprising at least one polymeric anion and at least one optionally substituted polyaniline and / or at least one polythiophene which has recurring units of the general formula (I), (II) or the recurring units of the general formula (I) and (II) Improved by this process, however, by this means the dense polymeric outer layers can not be reproduced reliably. Therefore, there continues to be a need for an improved process for the production of solid electrolytic capacitors having a low equivalent series resistance (ESR), whereby a simple and reliable reproduction of a dense polymeric outer layer with good coverage can be realized. the edges. Therefore the objective was to provide a process and the improved capacitors through this process. BRIEF DESCRIPTION OF THE INVENTION It has now been found, surprisingly, that dispersions comprising particles of a conductive polyaniline and / or, in particular, polythiophene having an average particle diameter in the range of 70-500 nm and a binder , meet these requirements.

The diameter distribution of the particles b) comprises a conductive polymer in the dispersions surprisingly has a considerable influence on the formation of the outer layers in the electrolytic capacitors. In particular, the edges and corners of the capacitor body can not be covered with a closed polymer film with dispersions comprising predominantly particles b) having an average diameter of less than 70 nm. The planned adjustment of the distribution of the particle diameter in the dispersions thus makes it possible to easily achieve a good coating of the corners and edges. The present invention therefore provides a process for the production of an electrolytic capacitor, wherein, on a capacitor body it comprises at least one porous body of the electrode of a material for the electrode, a dielectric, which covers the surface of the material for the electrode, a solid electrolyte comprising at least one electrically conductive material, preferably a conductive polymer, which completely or partially covers the dielectric surface, a dispersion a) is applied which comprises particles b) of an electrically conductive polymer which comprises at least one optionally substituted polyaniline and / or at least one polythiophene having the recurring units of the general formula (I) or the formula (II) or recurring units of the general formulas (I) and (II) wherein A represents an optionally substituted alkylene-Ci-Cs radical, R represents an optionally substituted straight or branched Ci-Ciß alkyl radical, an optionally substituted C5-C ?2 cycloalkyl radical, an aryl-C6-C radical? optionally substituted, optionally substituted C 7 -C 8 aralkyl radical, optionally substituted C 1 -C 4 hydroxyalkyl radical or a hydroxyl radical, x represents an integer from 0 to 8 and in the case where the different R radicals are attached to the A, these can be identical or different, and a binder c) and a dispersing agent d), and, for the formation of an electrically conductive polymeric outer layer, the dispersing agent d) is at least partially removed and / or the b) c) is cured, characterized in that the particles b) of the conductive polymer in dispersion a) have an average diameter of 70-500 nm. The general formulas (I) and (II) are understood to mean that the x's of the R substituents can be attached to the alkylene radical A. BRIEF DESCRIPTION OF THE FIGURES The invention is further illustrated by means of the following non-limiting drawings wherein: Fig. 1 is a schematic representation of the construction of a solid electrolytic capacitor; and Fig. 2 is an enlarged diagram in detail 10 of Fig. 1 and represents the construction of the schematic layer of the capacitor. . DETAILED DESCRIPTION OF THE INVENTION As used herein in the specification and claims, including as used in the examples and unless otherwise specified, all numbers may be read as if the term "approximately" is prefixed., even if the term does not appear expressly. Although, any numerical range recited herein is intended to include all sub-ranges included in a category herein. The diameter of the particles b) of the conductive polymer is related to a distribution of the particles b) in the dispersion a) as a function of the diameter of the particle. It is determined, for example, by means of ultracentrifugal measurement. In the process according to the invention, the particles b) of the conductive polymer in dispersion a) preferably have an average diameter of 90-400 nm, particularly preferably 100-300 nm. Preferably, the diameter distribution of the particles b) of the conductive polymer in the dispersion a) has a dio value greater than 50 nm and a value d90 lower than 600 nm, particularly preferably a dxo value greater than 70 nm and a value d90 less than 500 nm, particularly more preferably a value gave greater than 80 nm and a value d90 less than 400 nm. In this context, the value d? 0 of the diameter distribution states that 10% of the total weight of all particles b) of the conductive polymer in dispersion a) can be assigned to those particles b) having a diameter less than or equal to value given • The value d90 of the diameter distribution states that 90% of the total weight of all particles b) of the conductive polymer in dispersion a) can be assigned to those particles b) that have a diameter less than or equal to the value of d90 . In the electrolytic capacitor produced by the process according to the invention, the electrode material forms a porous body having a large surface area and is, for example, in the form of a porous sintered body or a rough film. In the following, this porous body is also called to reduce the electrode body's words. The body of the electrode covered with a dielectric also called oxidized electrode body to shorten in the following. The term "oxidized electrode body" also includes those electrode bodies that are covered with a dielectric that has not been prepared by oxidation of the electrode body. The body of the electrode covered with a dielectric and completely or partially with a solid electrolyte also called the body of the capacitor to shorten in the following. The electrically conductive layer which is prepared by means of the process according to the invention with the dispersion a) and which comprises at least one optionally substituted polyaniline and / or at least one polythiophene having recurring units of the general formula (I) or of the formula (II) or the recurring units of the formula (I) or (II) and at least one binder c), is called the polymeric outer layer. Preferably, the dispersion a) comprises at least one polymeric, organic binder c). Possible particularly preferred organic, polymeric c) binders are, for example, polyvinyl alcohols, polyvinyl pyrrolidones, polyvinyl chlorides, polyvinyl acetates, polyvinyl butyrates, polyacrylic acid esters, polyacrylic acid amides, polymethacrylic acid esters, acid amides. polymethacrylic, polyacrylonitriles, styrene / acrylic acid ester, vinyl acetate / acrylic acid ester and ethylene / virile acetate copolymers, polybutadienes, polyisoprenes, polystyrenes, polyethers, polyesters, polycarbonates, polyurethanes, polyamides, polyimides, polysulfones, resins of melamine / formaldehyde, epoxy resins, silicone resins or celluloses. Preferred possible polymeric organic binders c) are also those that are produced by the addition of crosslinking agents, such as, for example, melamine compounds, masked isocyanates, or functional silanes, such as, eg, 3- glycidoxypropyltrialkoxysilane, tetraethoxysilane, and tetraethoxysilane hydrolyzate, or crosslinkable polymers, such as, eg, polyurethanes, polyacrylates or polyolefins, and the subsequent crosslinking. These crosslinking products which are suitable as polymeric binders c) can also be formed, for example, by reaction of the crosslinking agent added with polymeric anions optionally contained in dispersion a). The preferred binders c) are those which have adequate heat stability in order to withstand the temperatures at which the finished capacitors are subsequently exposed, eg, the welding temperatures from 220 to 260 ° C. The solids content of the polymeric binder c) in the dispersion a) is 0.1-90% by weight, preferably 0.5-30% by weight and most preferably in particular 0.5-10% by weight. The dispersions a) may comprise one or more dispersing agents d). The following solvents can be mentioned as dispersing agents d) as an example medium: aliphatic alcohols, such as methanol, ethanol, i-propanol and butane; aliphatic ketones, such as acetone and methyl ethyl ketone; esters of aliphatic carboxylic acid, such as ethyl acetate and butyl acetate; aromatic hydrocarbons, such as toluene and xylene; aliphatic hydrocarbons, such as hexane, heptane and cyclohexane; chlorohydrocarbon, such as methylene chloride and dichloroethane; aliphatic nitriles, such as acetonitrile; aliphatic sulphoxides and sulphones, such as dimethylsulfoxide and sulfolane; amides of aliphatic carboxylic acid, such as methylacetamide, dimethylacetamide and dimethylformamide; and aliphatic and araliphatic ethers, such as diethyl ether and anisole. Water or a mixture of water with the organic solvents mentioned above can also be used as the dispersing agent d).

Preferred dispersing agents d) are water or other protic solvents, such as alcohols, eg, methanol, ethanol, i-propanol and butanol, and mixtures of water with these alcohols, water being the particularly preferred solvent. Where appropriate, the binder c) can also function as the dispersing agent d). In the context of the invention, the term polymer includes all compounds that have more than one identical or different recurring unit. The conductive polymers are understood to mean in the present in particular the class of conjugated polymers-p which have an electrical activity after oxidation or reduction. Preferably, the conductive polymers are understood to mean those conjugated polymers-p which have electrical conductivity of the order of at least 1 μS cm "1 after oxidation In the context of the invention, the prefix poly- is meant to mean that more than one identical or different recurring unit is contained in the polymer or polythiophene The polythiophenes contain a total of n recurring units of general formula (I) or formula (II) or of formulas (I) and (II), wherein n is an integer from 2 to 2,000, preferably 2 to 100. The recurring units of the formula (I) and / or (II) may in each case be identical or different within a polythiophene. - case identical recurring units of the general formula (s) (I), (II) or (I) and (II) The polythiophenes preferably carry H in each case in the final groups The solid electrolyte can comprise duct polymers optionally substituted polythiophenes, optionally substituted polypyrroles or optionally substituted polyanilines. The preferred conductive polymers of the solid electrolyte are the polythiophenes having recurring units of general formulas (I), (II) or recurring units of general formula (I) and (II), wherein A, R and x have the meaning given above for The general formulas (I) and (ID) are particularly preferred polythiophenes having recurring units of the general formula (I), (II) or recurring units of the general formulas (I) and (II) wherein A represents a optionally substituted C2-C3 alkylene radical and x represents 0 or 1. Poly (3,4-ethylenedioxythiophene) is particularly preferred as the solid electrolyte conductive polymer.C C-C5 alkylene radicals are preferably methylene, ethylene, n-propylene, n-butylene or n-pentylene In the alkyl L-CI8 R preferably represents the linear or branched C? -C? 8 alkyl radicals, such as methyl, ethyl, non-iso-propyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1-methylbutyl, 2-methyl l-butyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n- decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl, or n-octadecyl, the C5-C12 cycloalkyl radicals R represents, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl , the C3-C4 aryl radicals R represents, for example, phenyl or naphthyl, and C7-C8 aralkyl radicals R represents, for example, benzyl, o-, m-, p-tolyl, 2,3-, 2,4- , 2,5-, 2,6-, 3,4-, 3,5-xylyl or esityl. The above list serves to illustrate the invention as a means of exemplification and will not be considered as conclusive. Other possible substituents of the radicals A and / or radicals R are numerous organic groups, for example, the alkyl, cycloalkyl, aryl, aralkyl, alkoxy, halogen, ether, thioether, bisulfide, sulfoxide, sulphonate, sulfonate, amino groups, aldehyde, keto, carboxylic acid ester, carboxylic acid, carbonate, carboxylate, cyano, alkylsilane and alkoxysilane as well as the carboxamide groups.

Possible substituents for the aniline are, for example, the radicals A and R listed above and / or the other substituents of the radicals A and R. The unsubstituted polyanilines are preferred. The polythiophenes used as the solid electrolyte in the preferred process can be neutral or cationic. In preferred embodiments these are cationic, "cationic" is related only to the charges that are established in the main chain of polythiophene. Depending on the substituent on the radicals R, the polythiophenes can carry positive or negative charges in the structural unit, the positive charges are in the polythiophene backbone and the optionally negative charges are in the R radicals substituted by the sulfonate or carboxylate groups. In this context, the positive charges of the polythiophene backbone can be partially or completely satisfied by the anionic groups optionally present in the R radicals. Generally examined, the polythiophenes can be cationic, neutral or even anionic in these cases. However, in the context of the invention all are related as cationic polythiophenes, since the positive charges in the polythiophene backbone are decisive. The positive charges are not shown in the formulas, since their precise number and position can not be determined unambiguously. However, the number of positive charges is less than 1 and not greater than n, where n is the total number of all recurring units (identical or different) within the polythiophene. To compensate for the positive charge, if this has not been done for the sulfonate- or carboxylate- optionally substituted and therefore the R radicals are negatively charged, the cationic polythiophenes require anions as counter-anions. The counter-anions can be monomeric or polymeric anions, the latter are also called polyanions in the later. Polymeric anions for use in the solid electrolyte can be, for example, anions of polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acids or polymaleic acids, or polymeric sulfonic acids, such as polystyrenesulfonic acids and polyvinylsulfonic acids. These polycarboxylic and sulfonic acids can also be copolymers of vinylcarboxylic acids and vinylsulfonic acids with other polymerizable monomers, such as the esters of acrylic acid and styrene. Monomeric anions are preferably used for the solid electrolyte, since these penetrate better into the body of the oxidized electrode. The anions which serve as monomeric anions are, for example, those of C.sub.1 -C.sub.20 alkanesulfonic acids, such as methane-, ethane-, propane-, butane-, or higher sulfonic acids, such as dodecansulfonic acid, of aliphatic perfluorosulfonic acids, such as trifluoromethanesulfonic, perfluorobutanesulfonic or perfluorooctanesulfonic acid, of aliphatic C? -C20 carboxylic acids, such as 2-ethylhexylcarboxylic acid, of aliphatic perlfluorocarboxylic acids, such as trifluoroacetic acid or perfluorooctanoic acid and aromatic sulfonic acids optionally substituted by C? -C20 groups , such as benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid and cycloalkanesulfonic acids, such as camphorsulfonic acid, or tetrafluoroborates, hexafluorophosphates, perchlorates, hexafluoroantimonates, hexafluoroarsenates or hexachloroantimonates. The anions of p-toluenesulfonic acid, methanesulfonic acid or camphorsulfonic acid are preferred. Cationic polythiophenes containing anions as counter-ions for charge compensation are often also called polythiophene / (poly) anion complexes by persons skilled in the art. Further, to the conductive polymers and optionally also counter-ions, the solid electrolyte may comprise binders, cross-linking agents, surfactants, such as, eg, ionic or anionic surfactants or adhesion promoters and / or other additives. Adhesion promoters are, for example, organofunctional silanes or hydrolysates thereof, eg, 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane. The solid electrolyte preferably comprises the conductive polymer and the monomeric anions as the counter-ions. The solid electrolyte preferably forms a layer having a thickness of less than 200 nm, particularly preferably less than 100 nm, very particularly preferably less than 50 nm on the dielectric surface. The coating of the dielectric with the solid electrolyte can be determined as follows: The capacitance of the capacitor was measured at 120 Hz in the dry and wet state. The degree of coating in the ratio of the capacitance in the dry state to the capacitance in the wet state, expressed in percent. The dry state means that the capacitor has dried at high temperature (80-120 ° C) for several hours before being measured. The wet state means that the capacitor is exposed to an atmosphere saturated with moisture under high pressure, for example in a steam boiler under pressure, for several hours. During this procedure moisture enters the pores which are not covered by the solid electrolyte and acts as a liquid electrolyte. The coating of the dielectric by the solid electrolyte is preferably greater than 50%, particularly preferably greater than 70%, most preferably greater than 50%, particularly preferably greater than 80%. The polymeric outer layer is preferably, as shown schematically and as a means of exemplification in Figure 1 and Figure 2, in all or a portion of the outer surface of the capacitor body. The outer surface is understood to mean the outer surfaces of the capacitor body. Fig. 1 describes a schematic representation of the construction of a solid electrolytic capacitor with the example of a tantalum capacitor comprising 1 capacitor body 5 polymeric outer layers 6 layers of graphite / silver 7 contact wire with electrode body 2 8 external contacts 9 encapsulation 10 detail of the diagram Fig. 2 describes the enlarged detail 10 of the diagram of Fig. 1 which represents the construction of the schematic layer of the tantalum capacitor comprising the detail of the diagram 2 porous body of the electrode (FIG. anode) 3 dielectric 4 solid electrolyte 5 polymeric outer layer 6 graphite / silver layer The geometric surface area in the following is understood to mean the outer area of the capacitor body 1 which results in geometric dimensions. For the sintered bodies of rectangular parallelepipeds the geometric surface area is therefore: geometric surface area = 2 (L * B + L * H + B + H), where L is the length, B is the width and H is the height of the body and * is maintained for the multiplication symbol. In this context, only the part of the body of the capacitor 1 where the polymeric outer layer is present is considered.

If several capacitor bodies 1 are used in a capacitor, the individual geometric surface areas are added together to give a total geometric surface area. For solid electrolytic capacitors having, for example, a wound film as the porous body of the electrode, the dimensions of the uncoiled film (length, width) are used as the measurements. Instead of solid electrolytes comprising a conductive polymer, the solid electrolytic capacitors can also comprise solid electrolytes comprising a non-polymeric conductive material, such as, for example, charge transfer complexes, such as, for example, TCNQ (7, 7, 8, 8-tetracyano-1,4-quinodimethane), manganese dioxide or salts, such as, for example, those which can form ionic liquids. The polymeric outer layer also causes lower residual currents in such solid electrolytic capacitors. For the polythiophenes of particles b) of the electrically conductive polymer having recurring units of general formula (I), (II) or recurring units of general formula (I) and (II) which are in dispersion a), the same preferred structural characteristics as for the polythiophenes in the solid electrolyte. The polymeric or monomeric anions can function as the counter-ion for the polyanilines and / or polythiophenes of the particles b) having recurring units of the general formula (I), (II) or recurring units of the general formula (I) and (II) in the dispersion a). However, preferably, the polymeric anions serve as counterions in dispersion a). Polymeric anions can be, for example, anions of polymeric carboxylic acids, such as polyacrylic acids, polymethacrylic acids or polymaleic acids, or polymeric sulfonic acids, such as polystyrenesulfonic acids and polyvinylsulfonic acids. These polycarboxycarboxylic and -sulfonic acids may also be copolymers of vinylcarboxylic acids and vinylsulfonic acids with other polymerizable monomers, such as the esters of acrylic acid and styrene. An anion of a polymeric carboxylic or sulfonic acid is preferred as the polymeric anion in the aforementioned particles b). The anion of polystyrenesulfonic acid (PSS) is particularly preferred as the polymeric anion. The molecular weight of the polyacids that the polyanions provide is preferably 1,000 to 2,000,000, particularly preferably 2,000 to 500,000. The polyacids or their alkali metal salts are commercially available, eg, polystyrenesulfonic acids and polyacrylic acids or can be prepared by known processes (see, for example, Hoben Weyl, Methoden der organischen Chemie, Vol. E 20 Makromolekulare Stoffe, part 2, (1987), p.1141 et seq.). The dispersion a) may comprise the polymeric anion (s) and electrically conductive polymers in particular in a weight ratio from 0.5: 1 to 50: 1, preferably from 1: 1 to 30: 1, particularly in a preferred from 2: 1 to 20: 1. The weight of the polymers corresponds to the weight of the monomers used, assuming that the complete conversion takes place during the polymerization. The dispersion a) can also comprise monomeric anions. For monomeric anions, the same preferred anions apply as listed above for the solid electrolyte. The dispersion a) may further comprise other compounds, such as surface-active substances, eg, ionic and non-ionic surfactants or adhesion promoters, such as, eg, organofunctional silanes or hydrolysates thereof, eg, 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane. The thickness of the polymeric outer layer is preferably 1-1,000 μm, particularly preferably 1-100 μm, very particularly preferably 2-50 μm, especially and particularly preferably 4-20 μm. The thickness of the layer can vary on the outer surface. In particular, the thickness of the layer at the edges of the capacitor body may be thicker or thinner than on the side faces of the capacitor body. However, a virtually homogeneous layer thickness is preferred. The polymeric outer layer may have a homogeneous or inhomogeneous distribution with respect to its composition relative to the binder c) and the conductive polymer. Homogeneous distributions are preferred. The polymeric outer layer can be a constituent of a multilayer system that forms the outer layer of the capacitor body. Thus, one or more additional functional layers (eg, adhesion promoter layers) may exist between the solid electrolyte and the polymeric outer layer. However, the electrical function of the polymeric outer layer must not be damaged as a result. Other functional layers may also exist on the polymeric outer layer. In addition, there may be several polymeric outer layers on the capacitor body. Preferably, the polymeric outer layer is directly on the solid electrolyte. The polymeric outer layer preferably penetrates within the edge region of the capacitor body, in order to achieve a good electrical contact with the solid electrolyte and increase the adhesion of the capacitor body, but not within the depth of all the pores (Cf. Fig. 2 as means of exemplification). In a particularly preferred embodiment, the electrolyte capacitor produced by the novel process comprises a solid electrolyte comprising poly (3,4-ethylenedioxythiophene) (PEDT) and a polymeric outer layer comprising polystyrenesulfonic acid (PSS) and poly (3,4) -ethylenedioxythiophene), frequently the latter is also called PEDT / PSS or PEDOT / PSS in the literature. In a particularly preferred embodiment, the electrolytic capacitor produced by the novel process comprises a solid electrode of poly (3,4-ethylenedioxythiophene) and monomer counter-ions and a polymeric outer layer of PEDT / PSS and a binder c). A process for the production of electrolytic capacitors is characterized in that it is more preferred that the electrode material is a valve metal. In the context of the invention, the valve metal is understood to mean those metals from which the oxide layers do not provide current flow equally possible in both directions: if a voltage is applied to the anode, the oxide layers of the metals Valve blocks block the flow of current, while if a voltage is applied to the cathode, high currents are present, which can destroy the oxide layer. The valve metals include, Be, Mg, Al, Ge, Si, Sn, Sb, Bi, Ti, Zr, Hf, V, Nb, Ta and W as well as an alloy or compound of at least one of these metals with other elements. The best-known representatives of the valve metals are Al, Ta and Nb. Compounds having electrically comparable properties with a valve metal are those with metallic conductivity which can be oxidized and the oxide layers thereof having the properties described above. For example, the NbO has metallic conductivity, but in general it is not related to a valve metal. However, the oxidized NbO layers have the typical properties of the oxide layers of the valve metal, so the NbO or an alloy or compound of NbO with other elements are typical examples of these compounds that have comparable electrical properties to a metal valve. Therefore, the term "oxidizable metal" means not only metals but also an alloy or compounds of a metal with other elements, as long as they have metallic conductivity and can oxidize. Accordingly, the present invention particularly preferably provides a process for the production of electrolytic capacitors, characterized in that the valve metal or the compound having comparable electrical properties to a valve metal is tantalum, niobium, aluminum, titanium, zirconium , hafnium, vanadium, an alloy or compound of at least one of these metals "with other elements, NbO or an alloy or compound of NbO with other elements.

The dielectric preferably comprises an oxide of the electrode material. This optionally comprises other elements and / or compounds. The capacitance of the oxidized electrode body depends on the surface area and the thickness of the dielectric, as well as on the nature of the dielectric. The specific load is a measure of how much charge per unit weight of the oxidized electrode body can accumulate. The specific load is calculated as follows: Specific load - (capacitance * voltage) / body weight of the oxidized electrode.

The capacitance is obtained from the capacitance of the finished capacitor measured at 120 Hz and the voltage is the capacitor operating voltage (rated voltage). The body weight of the oxidized electrode is related to the pure weight of the porous electrode material covered with the dielectric, without polymer, contacts and encapsulations. Preferably, the electrolytic capacitors produced by the novel process having a specific charge greater than 10,000 μC / g, particularly preferably greater than 20,000 μC / g, very particularly preferably greater than 30,000 μC / g, extremely preferably higher of 40,000 μC / g. The solid electrolytic capacitor produced by the process according to the invention is distinguished by a low residual current and low equivalent series resistance. Since the outer polymer layer forms a dense layer around the body of the capacitor and the edges of these are covered very well, the capacitor body is strong against mechanical stress. In addition, the polymeric outer layer shows good adhesion to the capacitor body and high electrical conductivity, so that it can achieve low resistance in equivalent series. The present invention preferably provides electrolytic capacitors produced by the novel process which have an ESR, measured at 100 kHz, less than 50 mO. The ESR of the electrolytic capacitors produced by the novel process, measured with a frequency of 100 kHz, is particularly preferred less than 31 mO, very particularly preferred is less than 21 mO, extremely and particularly less than 16 mO is preferred. Particularly in the preferred embodiments of the electrolytic capacitors, the ESR is less than 11 mO. The equivalent series resistance of a solid electrolytic capacitor is inversely correlated with the geometrical surface area of the capacitor. The product of equivalent series resistance and geometric surface area therefore gives a parameter which is independent of the structural size. The present invention therefore also preferably provides electrolytic capacitors produced by the novel process wherein the product of equivalent series resistance, measured at 100 kHz, and the geometric surface area of the capacitor body is less than 4,000 mOmm2. the product of the equivalent series resistance and the geometric surface area is preferably particularly less than 3,000 mOmm 2, very particularly preferably less than 2,000 mOmm 2, extremely and preferably less than 1,000 mOmm 2. In the particularly preferred embodiments of the electrolytic capacitors, the product of the equivalent series resistance and the geometric surface area is less than mOmm2. In principle, such an electrolytic capacitor according to the invention can be produced as follows: First, eg, a valve metal powder having a large surface area is pressed and sintered to give a porous body of the electrode. In this process, an electrical contact wire of the same metal as the powder, eg, tantalum, is also conventionally pressed into the electrode body. Alternatively, the metal films can also be etched to strong water to obtain a porous film. The electrode body is then covered, for example by electrochemical oxidation, with a dielectric, that is, an oxide layer. Then a conductive polymer, which forms the solid electrolyte, is deposited chemically or electrochemically on the dielectric, eg, by means of the oxidation polymerization. For this reason, the precursors for the preparation of the conductive polymers, one or more oxidizing agents and optionally counter-ions are applied, together or successively, to the dielectric of the porous body of the electrode and subjected to chemical oxidizing polymerization, or the precursors for The preparation of the conductive polymers and counter ions are polymerized in the dielectric of the porous body of the electrode by means of electrochemical polymerization. After this, according to the invention, a layer comprising at least one optionally substituted polyaniline and / or a polythiophene having recurring units of general formula (I), (II) or recurring units of the general formula (I) and (II) and at least one binder c) is applied to the capacitor body from a dispersion a). Other layers are optionally applied to the polymeric outer layer. A coating with layers of good conductivity, such as graphite and silver, or a metal body of the cathode serves as the electrode for conducting the current. Finally, the capacitor is contacted and encapsulated. The precursors for the preparation of the solid electrolyte conducting polymers, also called precursors in the following, are understood to mean the corresponding monomers or derivatives thereof. The mixture of several precursors can also be used. Suitable monomer precursors are, for example, optionally substituted thiophenes, pyrroles, or anilines, preferably optionally substituted thiophenes, preferably 3,4-alkylenedioxythiophenes optionally substituted. The substituted 3,4-alkylenedioxythiophenes which may be mentioned as examples are the compounds of the general formula (III), (IV) or a mixture of thiophenes of the general formulas (III) and (IV). wherein A represents an optionally substituted C3-C5 alkylene radical, preferably an optionally substituted C2-C3 alkylene radical, R represents an optionally substituted, linear or branched, preferably linear or branched, C? -C? 8 alkyl radical, an alkyl radical C? -C optionally substituted, linear or branched, an optionally substituted C5-C? 2 cycloalkyl radical, an optionally substituted C6-C? 4 aryl radical, an optionally substituted C7-Ci8 aralkyl radical, a C? -C4 hydroxyalkyl radical optionally substituted, an optionally substituted C? -C hydroxyalkyl radical, or a hydroxyl radical, x represents an integer from 0 to 8, preferably from 0 to 6, particularly preferably 0 or 1 and in the case where several R radicals are attached to A, these can be identical or different. The optionally substituted 3,4-ethylenedioxythiophenes are the very preferred monomer precursors. The optionally substituted 3,4-ethylenedioxythiophenes which can be mentioned as exemplification are the compounds of general formula (V) where R and x have the same meaning for the general formulas (III) and (IV). In the context of the invention, the derivatives of these monomer precursors are understood to mean, for example, dimers or trimers of these monomer precursors. Derivatives of high molecular weight, ie, tetramers, pentamers, etc., derivatives of monomer precursors are also possible. The substituted 3,4-alkylene dioxythiophene derivatives which may be mentioned as exemplification are the compounds of general formula (VI) wherein n represents an integer from 2 to 20, preferably from 2 to 6, particularly preferably 2 or 3 and A, R and x have the meaning given for general formula (III) and (IV). The derivatives can be prepared with identical or different monomer units and can be used in the pure form and in a mixture with another and / or with the monomer precursors. The oxidized or reduced forms of these precursors are also included in the term "precursors" in the context of the invention, so that the same conducting polymers are formed during their polymerization as in the case of the precursors listed above. In the context of the invention, the C1-C5 alkylene radicals A are methylene, ethylene, n-propylene, n-butylene, or n-pentene. In the context of the invention, the R radicals of C? -C? 8 alkyl represent linear or branched C? -C? 8 alkyl radicals such as, for example, methyl, ethyl, n- or iso-propyl, n-, iso-, sec- or tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 1,1-dimethylpropyl, 1,2-dimethylpropyl, 2,2-dimethylpropyl, n- hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-hexadecyl or n-octadecyl, radicals R of C5-CX2 cycloalkyl represent, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, or cyclodecyl, aryl radicals C5-C4 represent, for example, phenyl or naphthyl, and the R radicals of aralkyl C7-Cis represent , for example, benzyl, o-, m-, p-tolyl, 2,3-, 2,4-, 2,5-, 2,6-, 3,4-, 3,5-xylyl or mesityl. The above list serves to illustrate the invention as a means of exemplification and is not considered conclusive. Other possible optional substituents of the radicals A and / or the radicals R are organic group numbers, for example the alkyl, cycloalkyl, aryl, aralkyl, alkoxy, halogen, ether, thioether, bisulfide, sulfoxide, sulphonate, sulfonate, amino groups, aldehyde, keto, carboxylic acid ester, carboxylic acid, carbonate, carboxylate, cyano, alkylsilane and alkoxysilane as well as the carboxamide groups. The possible substituents for the aforementioned precursors, in particular for the thiophenes, preferably for the 3, 4-alkylenedioxythiophenes, are the radicals mentioned for R in the general formulas (III) and (IV). Possible substituents for the pyrroles and anilines are, for example, the radicals A and R mentioned above and / or other substituents of the radicals A and R. The processes for the preparation of the monomer precursors for the preparation of the conducting polymers and derivatives of these are known to persons skilled in the art and are described, for example, in L. Groenendaal, F. Joñas, D. Freitag, H. Pielartzik & amp;; J.R. Reynolds, Adv. Matr. 12 (2000) 481-494 and the liture cited herein. The 3, 4-alkylenoxythiathiophenes of formula (III) required for the preparation of the polythiophenes to be used are known to persons skilled in the art or can be prepared by known processes (for example according to P. Blanchard, A. Cappon, E. Levillain, Y. Nicolás, P. Frére and J. Roncali, Org. Lett., 4 (4), 2002, pp. 607-609). The conductive polymers are preferably produced, in the body of the electrode covered with the dielectric, by means of the oxidative polymerization of the precursors for the preparation of the conducting polymers by a process wherein the precursors, the oxidizing agent and optionally the counions , preferably in the form of solutions, are applied to the dielectric of the electrode body either separately in succession or together and the oxidation polymerization is carried out until complete, optionally by heating the coating, depending on the activity of the oxidizing agent used. The application can be made in the dielectric of the electrode body directly or using an adhesion promo for example a silane, such as, for example, organofunctional silanes or hydrolysates thereof, eg, 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane, and / or one or more other functional layers. The oxidizing chemical polymerization of the thiophenes of the formula (s) (III) or (IV) is generally carried out at temperatures from -10 ° C to 250 ° C, preferably at temperatures from 0 ° C to 200 ° C. ° C, depending on the oxidizing agent used and the desired reaction time. The solvents which may be mentioned for the precursors for the preparation of conductive polymers and / or oxidizing agents and / or counions are all the following organic solvents which are inert under the reaction conditions: aliphatic alcohols, such as methanol, ethanol, i- propanol and butane; aliphatic ketones, such as acetone and methyl ethyl ketone; es of aliphatic carboxylic acid, such as ethyl acetate and butyl acetate; aromatic hydrocarbons, such as toluene and xylene; aliphatic hydrocarbons, such as hexane, heptane and cyclohexane; chlorohydrocarbon, such as methylene chloride and dichloroethane; aliphatic nitriles, such as acetonitrile; sulphoxides and aliphatic sulfones, such as dimethylsulfoxide and sulfolane; aliphatic carboxylic acid amides, such as methylacetamide, dimethylacetamide and dimethylformamide; and aliphatic and araliphatic ethers, such as diethyl ether and anisole. Waor a mixture of wawith the organic solvents mentioned above can also be used as the solvent. The oxidizing agents that can be used are all metal salts known to those skilled in the art which are suitable for the oxidative polymerization of thiophenes, anilines and pyrroles.

The salts of metals are the salts of metals of the main group or metals of the subgroup, the latter can also be called transition metal salts in the following, from the periodic table of the elements. The transition metal salts are, in particular, salts of an inorganic or organic acid or inorganic acid containing organic radicals with transition metals, such as, for example, with iron (III), copper (II), chromium (VI), cerium (IV), manganese (IV), manganese (VII) and ruthenium (III). The transition metal salts are those of iron (III). Conventional iron (III) salts are advantageously inexpensive and can be obtained easily and easily, such as, for example, iron salts (II) of inorganic acids, such as, for example, iron (III) halides (e.g., FeCl3) or iron salts (III) of other inorganic acids, such as Fe (C104) 3 or Fe (S04) 3 and the iron (III) salts of organic acids and inorganic acids containing organic radicals. Examples that may be mentioned of the iron (III) salts of inorganic acids containing organic radicals are the iron (III) salts of the monoesters of the alkali sulfuric acid L-C2O, P-eJ- / the iron salts (III) of lauryl sulfate. Particularly preferred transition metal salts are those of an organic acid, in particular iron (III) salts of organic acids. Examples that may be mentioned of the iron (III) salts of organic acids are: the iron (III) salts of C?-C20 sulf sulphonic alkane acids, such as methane-, ethane-, propane-, butane- or higher sulfonic acids , such as dodecylsulfonic acid, aliphatic perfluorosulfonic acids, such as trifluoromethanesulfonic acid, perfluorobutanesulfonic acid or perfluorooctanesulfonic acid, C? -C20 carboxylic acids, such as 2-ethylhexylcarboxylic acid, aliphatic perfluorocarboxylic acids, such as trifluoroacetic acid or perfluorooctanoic acid, and sulfonic acid compounds aromatics optionally substituted with C1-C20 alkyl groups, such as benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid or dodecylbenzenesulfonic acid, and cycloalkanesulfonic acids, such as, ca-sulfonic acid. Any of the desired mixtures of these iron (III) salts of organic acids mentioned above can also be employed. The use of the iron (III) salts of organic acids and inorganic acids containing organic radicals has a greater advantage than those that do not have a corrosive action. Particularly preferred as metal salts are iron p-toluenesulfonate (III), iron (III) o-toluenesulfonate, or a mixture of iron (III) p-toluenesulfonate and iron (III) o-toluenesulfonate. . Oxidizing agents that are most suitable are peroxo compounds, such as peroxodisulfates (persulfates), in particular alkali metal and ammonium peroxodisulfates, such as sodium and potassium peroxodisulfate, or alkali metal perborates - optionally in the presence of catalytic amounts of metal ions, such as iron, cobalt, nickel, molybdenum, or vanadium ions-and transition metal oxides, such as, for example, pyrolusite (manganese oxide (IV) or cerium oxide (IV)). For oxidative polymerization of the thiophenes of formula (III) or (IV), theoretically 2.25 equivalents of the oxidizing agent are required per mole of thiophene (see, eg, J. Polym, Sc. Part A of Polymer Chemistry Vol. , p.1287 (1988).) However, lower or higher equivalents of the oxidizing agent can also be used In the context of the invention, preferably one or more equivalents, particularly preferably 2 equivalents or more of the same are used. oxidizing agent per mole of thiophene. If the precursors, the oxidizing agents and optionally the counter-ions are applied separately, the dielectric of the electrode body is preferably coated initially with the solution of the oxidizing agent and optionally the counter-ions and then with the solution of the precursors. In the case of the preferred mutual application of the precursors, the oxidizing agent and optionally the counter-ions, the dielectric of the electrode body is coated only with a solution, mainly a solution containing the precursors, the oxidizing agent and optionally the counter-ions. In addition, other compounds may be added to the solutions, such as one or more organic binders which are soluble in organic solvents, such as polyvinyl acetate, polycarbonate, polyvinyl butyral, polyacrylic acid esters, polymethacrylic acid esters, polystyrene, polyacrylonitrile, polyvinyl, polybutadiene, polyisoprene, polyethers, polyesters, silicones or styrene / acrylic acid ester, vinyl acetate / acrylic acid ester and ethylene / vinyl acetate copolymers, or water soluble binders such as polyvinyl alcohols, crosslinking agents , such as melamine compounds, masked isocyanates, functional silanes - e.g., tetraethoxysilane, alkoxysilane hydrolysates, eg, based on tetraethoxysilane, epoxysilanes, such as 3-glycidoxypropyltrialkoxysilane - polyurethanes, polyacrylates or polyolefins dispersions, and / or additives such as, for example, surfactants, e.g., surfactants i nicos or nonionic or adhesion promoters, such as organofunctional silanes and hydrolysates of these, eg, 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane or octyltriethoxysilane. The solutions that will be applied to the dielectric of the electrode body preferably contain from 1 to 30% by weight of the thiophene of general formula (III) or of the thiophene mixture of general formulas (III) and (IV) and from 0 to 50% by weight of the binder, crosslinking agent and / or additives, both percentages by weight are based on the total weight of the mixture. The solutions are applied to the dielectric of the electrode body by means of known processes, eg, by impregnation, png, dipping, spraying, atomizing, knife coating, brushing, rotating coating or printing, for example, ink injection, sieving, contact or tampon printing. The elimination of the solvents after the application of the solutions can be carried out by simple evaporation at room temperature. However, to achieve higher processing speeds it is more advantageous to remove solvents at elevated temperatures, eg, with temperatures from 20 to 300 ° C,. preferably from 40 to 250 ° C. A subsequent heat treatment can be combined directly with the removal of solvents, or it can be done with a time subtracted from the production of the coating. The duration of the heat treatment is from 5 seconds to several h, depending on the nature of the polymer used for the coating. The temperature profiles with different temperatures and also can be used detention times for the thermal treatment. The heat treatment can be carried out, for example, by means of a process in which the body of the coated oxidized electrode is moved through the heating chamber, which is at the desired temperature, with a speed such that the time is achieved of desired stop at the chosen temperature, or is brought into contact for the desired dwell time with a hot plate which is at the desired temperature. In addition, the heat treatment can be carried out, for example, in a heating furnace or several heating furnaces each having different temperatures. After removal of the solvents (drying) and, where appropriate, after the heat treatment, it may be advantageous to wash excess excess oxidizing agent and residual salts out of the coating with a suitable solvent, preferably water or alcohols. The residual salts are understood to mean the salts of the reduced form of the oxidizing agent and, where appropriate, other salts present.For metal oxide dielectrics, such as, for example, the oxides of the valve metals, after the polymerization and preferably during or after the washing, it may be advantageous to re-form the oxide film electrochemically, a. In order to repair any defect in the oxide film and by means of this decrease the residual current of the finished capacitor. During this so-called new formation, the capacitor body is immersed within an electrolyte and a positive voltage is applied to the electrode body. The flowing current re-forms the oxide in the defects in the oxide film or the conductive polymer destroyed in the defects on which a high current flows. Depending on the nature of the oxidized electrode body, it may be advantageous to impregnate the oxidized electrode body with the mixture several times, preferably after a wash, in order to achieve thicker polymer layers. The polythiophenes of the solid electrolyte can also be prepared with the precursors by means of the electrochemical oxidation polymerization. In electrochemical polymerization, the electrode body coated with a dielectric can first be coated with a thin layer of a conductive polymer. After the application of a voltage to this layer, the layer comprising the conductive polymer grows on it. Other conductive layers can also be used as the deposition layer. Thus, Y. Kudoh et al., In Journal of Power Sourses 60 (1996) 157-163 discloses the use of a manganese oxide deposition layer. The electrochemical oxidation polymerization of the precursors can be carried out at temperatures ranging from -78 ° C to the boiling temperature of the solvent used. The electrochemical polymerization is preferably carried out at temperatures from -78 ° C to 250 ° C, preferably in particular from -20 ° C to 60 ° C. The reaction time is from 1 minute to 24 hours, depending on the precursor used, the electrode used, the temperature chosen and the specific current applied. If the precursors are liquid, electropolymerization can be carried out in the presence or absence of solvents which are inert under the conditions of electropolymerization; The electropolymerization of the solid precursors is carried out in the presence of solvents which are inert under the conditions of electrochemical polymerization. In certain cases it may be advantageous to use mixtures of solvents and / or to add solubilization agents (detergents) to the solvents. Examples that can be mentioned of the solvents that are inert under the electropolymerization conditions are: water; alcohols, such as methanol and ethanol; ketones, such as acetophenone; halogenated hydrocarbons, such as methylene chloride, chloroform, carbon tetrachloride and fluorohydrocarbons; esters such as ethyl acetate and butyl acetate; esters of carbonic acid, such as propylene carbonate; aromatic hydrocarbons, such as benzene, toluene and xylene; aliphatic hydrocarbons, such as pentane, hexane, heptane and cyclohexane; nitriles, such as acetonitrile and benzonitrile; sulfoxides such as dimethisulfoxide; sulfones such as dimethyl sulfota, phenyl methyl sulfota and sulpholana; liquid aliphatic amides, such as methylacetamide, dimethylacetamide, dimethylformamide, pyrrolidone, N-methylpyrrolidone and N-methylcaprolactam; mixed aliphatic and aromatic-aliphatic ethers, such as diethyl ether and anisole; and liquid ureas, such as tetramethylureas or N, N-dimethyl-imidazolidinone. For electropolymerization, electrolyte additions are made to the precursors or solutions thereof. The electrolyte additions that are preferably used are free acids or conventional conductive salts that have a certain solubility in the solvents used. The electrolyte additions which have proven to be suitable are, for example, free acids, such as p-toluenesulfonic acid and methanesulfonic acid, and also the salts with alkasulfonate, aromatic sulfonate, tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexafluoroarsenate and hexachloroantimonate, and alkali metals, alkaline earth metals or optionally alkylated oxonium and sulfonium, phosphonium, ammonium cations. The concentrations of the precursors can be between 0.01 and 100% by weight (100% by weight only in the case of the liquid precursor); the concentrations are preferably from 0.1 to 20% by weight. The electropolymerization can be carried out discontinuously or continuously. The specific currents for electropolymerization can vary within wide limits; specific currents are conventionally used from 0.0001 to 100 mA / cm2, preferably from 0.01 to 40 mA / cm2. Voltages are established from approximately 0.1 to 50 V for these specific currents. For metal oxide dielectrics, it may be advantageous to re-form the oxide film electrochemically after the electrochemical polymerization in order to repair any defect in the oxide film and thereby decrease the residual current of the finished capacitor (reforming). Suitable counter ions are monomeric or polymeric anions already listed above, preferably those of alkane- or cycloalkanesulfonic acids or aromatic, monomeric or polymeric sulfonic acids. Particular preference is given to alkane- or cycloalkane-sulphonic acid anions or monomeric aromatic sulfonic acids for use in the electrolytic capacitors according to the invention, since the solutions containing these are more suitable for penetrating the coating of the porous material of the invention. electrode with a dielectric, and thus a greater contact area can be formed between it and the solid electrolyte. Counter-ions are added to the solutions, for example, in the form of their alkali metal salts or as free acids. In the case of electrochemical polymerization, these counter-ions are optionally added to the solution or the thiophenes as additions of the electrolyte or conductive salts. The anions that can be present in the oxidizing agent used can also serve as counter-ions, so that in the case of chemical oxidation polymerization, an extra addition of counter-ions is not absolutely necessary. After preparation of the solid electrolyte, the polymeric outer layer is applied as described above. The addition of the binders c) to the dispersion a) has the great advantage that the adhesion of the polymeric outer layer to the capacitor body increases. In addition, the binder c) increases the solids content in the dispersion, so that the suitable thickness of the outer layer can be easily reached with an impregnation and the coating of the edges is significantly improved. The dispersions a) may further comprise crosslinking agents, surfactants, such as, for example, ionic or nonionic surfactants or adhesion promoters, and / or additives. The crosslinking agents, surfactants and / or additives that may be used are those listed above for solid electrolytes. The dispersions a) preferably comprise other additives which increase the conductivity, such as, for example, compounds containing ether groups, such as, for example, tetrahydrofuran, compounds containing the lactone group, such as? -butyrolactone and? -valerolactone, compounds containing amide or lactam groups, such as caprolactam, N-methylcaprolactam, N, N-dimethylacetamide, N-methylacetamide, N, N-dimethylformamide (DMF), N-methylformamide, N-methylformanilide, N-methylpyrrolidone (NMP), N-octylpyrrolidone and pyrrolidone, sulfones and sulfoxides, such as, for example, sulfolane (tetramethylene sulfota) and dimethyl sulfoxide (DMSO), sugars or sugar derivatives, such as, for example, sucrose, glucose, fructose, and lactose, sugar alcohols, such as, for example, sorbitol and mannitol, furan derivatives, such as, for example, 2-furancarboxylic acid and 3-furancarboxylic acid, and / or di- or polyalcohols, such as, for example, ethylene glycol, glycerol, and triethylene glycol. Tetrahydrofuran, N-methylformamide, N-methylpyrrolidone, ethylene glycol, dimethisulfoxide or sorbitol are particularly preferred as additives that increase the conductivity. The dispersions a) can have a pH of 1-14, and a pH of 1-8 is preferred. For dielectrics sensitive to corrosion, such as, for example, aluminum oxides, dispersions having a pH of 4-8 are preferred, so as not to damage the dielectric. The dispersions of the optionally substituted anilines, thiophenes of the general formula are prepared (II), (IV) or mixtures of thiophenes of the general formula (III) and (IV), for example, analogously to the conditions mentioned in EP-A 440 957 (US 5,300,575). The possible oxidizing agents and solvents are those already listed above. The diameter distribution of the particles b) can be adjusted, for example, via a high pressure homogenization. A preparation of the polyaniline / polyanion or polythiophene / polyanion complex and the subsequent dispersion or a new dispersion in one or more solvent (s) is also possible. The dispersions a) are applied to the capacitor body by means of known processes, eg by rotating coating, impregnation, pouring, dipping, spraying, atomizing, knife coating, brushing, or printing, for example, inkjet , sieving, contact or tampon printing. The viscosity of the dispersion a) may be between 0.1 and 100,000 mPa.s (measured with a cutting speed of 100 s "x), depending on the application method, Preferably, the viscosity is from 1 to 10,000 mPa.s, particularly preferably between 10 and 1,000 mPa.s, very particularly preferably between 30 and 500 mPa.s. In the case of the application of the dispersion a) to the body of the capacitor by means of impregnation, it may be advantageous to allow it to be form a thin film of higher viscosity on the surface of the dispersion a) before impregnation, if the capacitor body is subsequently immersed deeper in a dispersion a) in one or more cycles of impregnation and drying, the coating of the edges and corners of the capacitor body is significantly improved and the formation of bubbles in the dry polymer film is eliminated, this is only possible for the middle of the capacitor body, for example, to be impregnated in the dispersion a) in the first step and then it will dry. In a second impregnation step, the capacitor body can then be completely immersed in the dispersion a) and subsequently dried. The formation of the thinner film of higher viscosity on the surface of dispersion a) can be achieved, for example, by simply allowing it to remain in the open atmosphere. The formation of the film can be accelerated, eg by heating the dispersion a) or by heating the surface of the dispersion with hot air or radiant heat. Preferably, dispersions a) having a specific conductivity in the dry state of greater than 10 S / cm, particularly preferably greater than 20 S / cm, very particularly preferably greater than 50 S / cm, and extremely and particularly are used. preferably greater than 100 S / cm. The application of the polymeric outer layer can also be followed by drying, cleaning the layer by means of washing, re-forming and application of several times - as already described above for the preparation of the solid electrolyte. The dispersing agent d) is preferably removed during drying. However, at least some of the dispersing agent d) can also remain in the polymeric outer layer. Additional treatment step, such as, for example, curing or cross-linking with heat or light, may also be applied, depending on the binder or the cross-linking agent used. In addition, the additional layers can be applied to the polymeric outer layer. It has been found that for the metal oxide dielectrics, after the application and drying of the dispersion a) no further treatment steps on the layer are necessary in order to produce the solid electrolytic capacitors having a low ESR and low residual current . In other processes for the preparation of a polymeric outer layer, the oxide layer conventionally has to be formed again after the application of the conductive polymeric outer layer, to achieve low residual currents. The polymeric outer layer can be locally separated from the capacitor body, which is why it is formed again in an electrolyteAs a result of this the ESR is increased. If the process according to the invention is used, the new formation can be dispensed with without increasing the residual current. After preparation of the polymeric outer layer, other layers of good conductivity, such as, for example, gaffite and / or silver layers, are optionally applied to the capacitor, and the capacitor is contacted and encapsulated. The valve metals or compounds having comparable electrical properties listed above for the electrolytic capacitor are preferably used for the production of the electrode body. Therefore, preferred ranges apply. Oxidizable metals are sintered, for example, in powder form to give a porous body of the electrode, or a porous structure is printed on a metal body. The latter can be done eg. , by etching a film. The porous bodies of the electrodes are oxidized, for example, in a suitable electrolyte, such as, for example, phosphoric acid with application of a voltage. The level of this formation voltage depends on the thickness of the oxide layer that will be achieved or the ultimate use voltage of the capacitor. Preferred voltages are from 1 to 300 V, preferably in particular from 1 to 80 V. Preference is given to using metal powders having a specific charge of greater than 35,000 μC / g, particularly preferably having a higher specific charge. 45,000 μC / g, very particularly preferably having a specific charge of greater than 65,000 μC / g, extreme and particularly preferably having a specific load higher than 95,000 μC / g, for the preparation of the electrode body. In the preferred embodiments of the process according to the invention, metal powders having a specific charge higher than 140,000 μC / g are used. In this context, the specific load is calculated as follows: Specific load = (capacitansia * voltage) / weight of the oxidized body of the electrode.

In this context, the capacitance of the capacitance of the oxidized electrode body, measured at 120 Hz, is obtained in an aqueous electrolyte. The electrical conductivity of the electrolyte here is high enough for a drop in capacitance due to the electrical resistance of the electrolyte however it occurs at 120 Hz. For example, the aqueous sulfuric acid electrolyte at 18% concentration is used for the measurement. The voltage in the above formula corresponds to the maximum forming voltage (oxidation voltage). Solid electrolytic capacitors having a dense polymeric outer layer which has good edge coverage and adhesion can be produced particularly in a simple manner with the process according to the invention. At the same time, the capacitors are distinguished by low residual currents and low ESR. Based on their low residual currents and low ESRs, the electrolytic capacitors produced according to the invention are outstandingly suitable for use as a component in electronic circuits. The present invention also provides the use. Digital electronic circuits as they exist, for example, are preferred in computers, (desktop computer, personal computer, server), in portable electronic equipment, such as, for example, mobile phones and digital cameras, in electronic equipment for entertainment, as in, for example, CD / DVD players and computer game consoles, navigation systems and telecommunications equipment.

EXAMPLES Example 1 1. Production of the oxidized bodies of the electrode Tantalum powder having a specific capacitance of 50,000 μFV / g, with the inclusion of tantalum cable 7, was pressed into granules 2 and sintered to form a porous body of the electrode. 2 which has the dimensions of 4.2 mm * 3 mm * 1.6 mm. The sintered granules 2 (granules of the anode) were anodized in a phosphoric acid electrolyte at 30 V- 2. In situ chemical coating of anode granules A solution comprising one part by weight of 3,4-ethylenedioxythiophene (BAYTRON® M, HC Starck GmbH) and 20 parts by weight of an ethanolic solution of iron p-toluenesulfonate (III) was prepared ) with 40% concentration. The solution was used for the impregnation of 18 granules of the anode 2. The granules of the anode 2 were impregnated in this solution and then dried at room temperature (20 ° C) for 30 minutes. After this, they were thermally treated in a drying cabinet at 50 ° C for 30 minutes. The granules 2 were then washed in an aqueous solution of p-toluene with 2% concentration. The granules of the anode 2 were reformed in an aqueous solution of p-toluenesulfonic acid with 0.25% concentration for 30 minutes, then rinsed in distilled water and dried. The impregnation, drying, heat treatment and new formation described were performed twice more with the same granules 23. Preparation of a dispersion A according to the invention. Initially in a 2 L three-necked flask with an internal thermometer and stirrer were introduced 868 g of deionized water and 330 g of polystyrenesulfonic acid aqueous solution having an average molecular weight of 70,000. and a solids content of 3.8% by weight. The reaction temperature was maintained between 20 and 25 ° C. 5.1 g of 3,4-ethylenedioxythiophene were added with stirring. The solution was stirred for 30 minutes. Then 0.03 g of iron (III) sulfate and 9.5 g of sodium persulfate were added and the solution was stirred for another 24 hours. After the reaction was finished, 100 ml of a strongly acidic cation exchanger and 250 ml of a weakly basic anion exchanger were added to remove the inorganic salts and the solution was stirred for another 2 hours. The ion exchanger was filtered. The dispersion of poly (3, 4-ethylenedioxythiophene) / polystyrenesulfonate obtained had a solids content of 1.2% by weight and the following distribution of the particle diameter: dlO 100 n d50 141 nm d90 210 nm The diameter of the particles b) of the conductive polymer is based on a weight distribution of the particles b) in the dispersion as a function of the diameter of the particles. The determination was made by means of an ultracentrifuge measurement. 90 parts of this dispersion were poly (3,4-ethylenedioxythiophene) / polystyrenesulfonate, 4 parts of dimethylsulfoxide (DMSO), 4.2 parts of a sulphonated polyester (Eastek® 1200, solids content of 30% by weight in water, (S) Eastman) and 0.2 parts of surfactant (Zonyl FS 300, DuPont) to form a dispersion A according to the invention. 4. Preparation of a dispersion B with conductive particles b) having an average diameter of less than 70 nm (comparison) Initially a 2 L three-necked flask was introduced with an internal thermometer and stirrer, 868 g of deionized water and 330 g of solution Aqueous polystyrenesulfonic acid having an average molecular weight of 70,000 and a solids content of 3.8% by weight. The reaction temperature was maintained between 20 and 25 ° C. 5.1 g of 3,4-ethylenedioxythiophene were added with stirring. The solution was stirred for 30 minutes. Then 0.03 g of iron (III) sulfate and 9.5 g of sodium persulfate were added and the solution was stirred for another 24 hours. After the reaction had been completed, 100 ml of a strongly acidic cation exchanger and 250 ml of a weakly basic anion exchanger were added to remove the inorganic salts and the solution was stirred for a further 2 hours. The ion exchanger was filtered. The dispersion of 2,4-polyethylenedioxythiophene / polystyrenesulfonate without salts was homogenized with a high pressure homogenizer 4 x under 250 bar. The dispersion of 3,4-polyethylenedioxythiophene / polystyrenesulfonate obtained in this way had a solids content of 1.2% by weight and the following particle diameter distribution: dlO 10 nm d 50 31 nm d 90 66 nm 90 parts of this dispersion were stirred poly (3,4-ethylenedioxythiophene) / polystyrenesulfonate, 4 parts of dimethylsulfoxide (DMSO), 4.2 parts of a sulfonated polyester (Eastek * 1200, solids content of 30% by weight in water, Eastman) and 0.2 parts of surfactant (Zonyl) ® FS 300, DuPont) to form a dispersion B according to the invention.

. Preparation of a polymeric outer layer In each of the cases 9 granules of the anode 2 were then impregnated in the dispersion A according to the invention and another 9 granules 2 were impregnated in the dispersion B and then the granules were dried at 120 ° C. for 10 minutes. The impregnation and drying were repeated once again for all the granules 2. After the application of the polymeric outer layer 5, the granules of the anode were checked under an optical microscope. The granules of the anode 2 according to the invention with the polymeric outer layer 5 based on the dispersion A were covered with a dense film of the polymer on the entire external surface. The edges and corners also showed a continuous coating of the polymer film. The granules of the anode 2 with the polymeric outer layer 5 based on the dispersion B showed no coating with the polymer film in particular at the corners and upper edges of the anode. Finally, the granules 2 were covered with a layer of graphite and silver. Capacitors 9 averaged the following electrical residual currents in each case: The residual current was determined with a Keithley 199 multimeter three minutes after the application of a voltage of 10 V. Due to better coating with a polymeric outer layer 5, the capacitors produced with the process according to the invention using the particles b ) comprising the dispersions of a conductive polymer having an average diameter of 141 nm show significant decrease of the residual currents. In the process which is not according to the invention, with particles b) comprising the dispersion of a conductive polymer having an average diameter of 31 nm, the graphite and silver layer evidently comes into direct contact with the dielectric , so the high residual current is increased. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (3)

CLAIMS Having described the invention as above, the content of the following claims is claimed as property: 1. Process for the production of an electrolytic capacitor, characterized in that on the body of the capacitor it comprises at least one porous body of the electrode of a material for the electrode, a dielectric, which covers the surface of this material for the electrode, a solid electrolyte comprising at least one electrically conductive material, which completely or partially covers the dielectric surface, a dispersion is applied which comprises particles of an electrically conductive polymer the which comprises at least one optionally substituted polyaniline and / or a polythiophene having recurring units of the general formula (I) or the formula (II) or recurring units of the general formulas (I) and (II) wherein A represents an optionally substituted C 1 -C 5 alkylene radical, R represents an optionally substituted straight or branched C 1 -C 8 alkyl radical, an optionally substituted C 5 -C 20 cycloalkyl radical, an aryl C 3 radical C14 optionally substituted, an optionally substituted C7-C18 aralkyl radical, an optionally substituted hydroxyalkyl-C? -C radical or a hydroxyl radical, x represents an integer from 0 to 8 and in the case where the different R radicals are attached to the A, these may be identical or different, and a binder and a dispersing agent, and, for the formation of an electrically conductive polymeric outer layer, the dispersing agent is at least partially removed and / or the binder is cured, wherein the particles of the conductive polymer in dispersion a) have an average diameter of 70-500 nm. Process according to claim 1, characterized in that the value of the particle diameter distribution of the conductive polymer in the dispersion is greater than 50 nm and the d90 value of the diameter distribution of the particles is less than 600 nm. Process according to claim 1, characterized in that the polythiophene in the dispersion is poly (3,4-ethylenedioxythiophene). 4. Process according to claim 1 ', characterized in that the dispersion additionally comprises at least one polymeric anion. Process according to claim 4, characterized in that the polymeric anion is an anion of a polymeric carboxylic or sulfonic acid. 6. Process according to claim 1, characterized in that the binder contained in the dispersion a) is a polymeric organic binder. Process according to claim 1, characterized in that the dispersion comprises, as the dispersing agent, organic solvents, water or mixtures thereof. 8. Process according to claim 1, characterized in that the dispersion additionally comprises crosslinking agents and / or surfactants and / or other additives. Process according to claim 8, characterized in that the dispersion comprises other additive compounds containing ether, lactone, amide or lactam groups, sulfones, sulfoxides, sugars, sugar derivatives, sugar alcohols, furan derivatives and / or diols. - or polyalcohols. 10. Process according to claim 1, characterized in that in the case of a pH-sensitive dielectric, the dispersion is adjusted to a pH of 4-8. 11. Process according to claim 1, characterized in that the conductive material of the solid electrolyte is a conductive polymer. 12. Process according to claim 11, characterized in that the conductive polymer contained in the solid electrolyte is a polythiophene, polypyrrole or polyaniline, which are optionally substituted. Process according to claim 12, characterized in that the conductive polymer contained in the solid electrolyte is a polythiophene having recurring units of the general formula (I) or of the formula (II) or recurring units of the general formulas (I ) and (II) wherein the radicals A and R and the index x have the meaning given in claim 1. 14. Process according to claim 13, characterized in that the conductive polymer contained in the solid electrolyte is poly (3,4-ethylenedioxythiophene). 15. Process according to claim 1, characterized in that the solid electrolyte comprises monomeric anions. 16. Process according to claim 1, characterized in that the electrode material of the electrode body is a valve metal or a compound having comparable electrical properties to the valve metal. Process according to claim 16, characterized in that the valve metal or the compound having comparable electrical properties with a valve metal is tantalum, niobium, aluminum, titanium, zirconium, hafnium, vanadium, an alloy or compound at least of one of these metals with other elements, NbO or an alloy or compound of NbO with other elements. 18. Process according to claim 1, characterized in that the dielectric is an oxide of the valve metal or an oxide of the compound having comparable electrical properties with a valve metal. 19. Process according to claim 1, characterized in that after the application of the dispersion and the formation of the electrically conductive polymeric outer layer, the capacitor is optionally provided with other electrically conductive outer contacts, optionally in contact and encapsulated. 20. Electrolytic capacitor, characterized because it is produced by a process in accordance with the claim

1. 21. Electrolytic capacitor according to claim 20, characterized in that the average layer thickness of the polymeric outer layer is 1-100 μm. Electrolytic capacitor according to claim 20, characterized in that the electrolytic capacitor has a specific load of greater than 10,000 μC / g, based on the weight of the electrode body covered with a dielectric. 23. An electronic circuit, characterized in that it comprises the electrolytic capacitor according to claim 20.