Polymer Capacitor Manufacturing Process for High Reliability Applications

Abstract

The present invention relates to a process for manufacturing a capacitor, the process comprising the following process steps: a) providing a porous electrode body (1) made of an electrode material (2), wherein a dielectric (3) at least partially covers the surface of said electrode material (2); b) introducing a liquid composition comprising a conductive polymer and a dispersant into at least a portion of said porous electrode body (1) provided in process step a), wherein a conductive layer made from said liquid composition has a conductivity of less than 100 S / cm; c) forming a solid electrolyte layer (4) at least partially covering the surface of the dielectric (3). To achieve this, the process comprises the steps of at least partially removing the dispersing agent from the porous electrode body (1) obtained in process step b), d) filling at least some of the pores (5) of the porous electrode body (1) obtained in process step c) with an impregnation solution comprising at least one impregnation solvent, the at least one impregnation solvent having a boiling point (measured at 1013 hPa) of at least 150°C, e) encapsulating the porous electrode body (1) obtained in process step d), and f) heating the encapsulated electrode body obtained in process step e) at a temperature above 50°C for more than 10 minutes. The present invention also relates to the use of capacitors, electrolytic capacitors and electronic circuits produced by this process.

Description

[Technical Field]

[0001] The present invention relates to a process for manufacturing a capacitor, to a capacitor obtainable by this process, to the use of such a capacitor, and to an electronic circuit.

[0002] A standard electrolytic capacitor generally consists of a porous metal electrode, an oxide layer disposed on the metal surface, a generally solid conductive material introduced into the porous structure, an external electrode (contact) such as a silver layer, and other electrical contacts and encapsulants. One frequently used electrolytic capacitor is the tantalum electrolytic capacitor, in which the anode electrode is made of the valve metal tantalum, on which a uniform dielectric layer of tantalum pentoxide is anodized (also called "formed"). A liquid or solid electrolyte forms the cathode of the capacitor. Aluminum capacitors, in which the anode electrode is made of the valve metal aluminum, on which a uniform, electrically insulating aluminum oxide layer is anodized as the dielectric, are also frequently used. Again, a liquid or solid electrolyte forms the cathode of the capacitor. Aluminum capacitors are generally implemented as wound or stacked capacitors.

[0003] Considering their high electrical conductivity, π-conjugated polymers are particularly suitable as solid electrolytes in the above-mentioned capacitors. π-conjugated polymers are also called conductive polymers or synthetic metals. Compared to metals, polymers have advantages in terms of processing, weight, and the ability to selectively adjust properties through chemical modification, so conjugated polymers are becoming increasingly important commercially. Examples of known π-conjugated polymers include polypyrrole, polythiophene, polyaniline, polyacetylene, polyphenylene, and poly(p-phenylene-vinylene). Poly(3,4-ethylene-dioxythiophene) (PEDOT) is a particularly important polythiophene used technically due to its very high electrical conductivity in the oxidized form.

[0004] In the prior art, alternative methods have been developed for producing solid electrolytes based on conductive polymers in electrolytic capacitors. For example, German Patent Application No. 102005043828 (A) describes a process for producing a solid electrolyte in a capacitor in which a dispersion containing already polymerized thiophene, such as the PEDOT / PSS dispersion known from the prior art, is applied to an oxide layer, and then the dispersion medium is removed by evaporation.

[0005] However, it has been observed that the electrical properties of capacitors used in electronic circuits deteriorate over their lifetime, especially due to the switching on and off processes of the electronic circuits or due to exposure to high temperatures over time. This is especially true for the capacitance of capacitors whose solid electrolyte layer is based on PEDOT / PSS.

[0006] The present invention was based on the object of overcoming the drawbacks arising from the prior art in relation to capacitors, preferably in relation to solid electrolytic capacitors, more preferably in relation to capacitors known from the prior art which comprise a solid electrolyte layer based on a π-conjugated polymer such as PEDOT, even more preferably in relation to capacitors known from the prior art which comprise a solid electrolyte layer based on PEDOT / PSS.

[0007] In particular, the invention is based on the object of providing a process for manufacturing capacitors, which makes it possible to produce capacitors that, when used in electronic circuits, exhibit electrical properties that are as constant as possible over as long a period as possible, in particular a capacitance that changes as little as possible.

[0008] It was also an object of the present invention to provide a capacitor having low equivalent series resistance (ESR) and high reliability, particularly in terms of capacitance at high temperatures.

[0009] The advantageous capacitor manufacturing process described above is also further characterized in that it makes it possible to manufacture these capacitors in the simplest possible way, in particular with as few process steps as possible.

[0010] A contribution to at least partially solving at least one, preferably two or more of the above mentioned objects is made by the independent claims. The dependent claims provide preferred embodiments that contribute to at least partially solving at least one of the objects.

[0011] |1a| At least one of the objects according to the present invention is a process for manufacturing a capacitor, preferably an electrolytic capacitor, comprising the following process steps: a) providing a porous electrode body made of an electrode material, wherein a dielectric material at least partially covers a surface of the electrode material; b) i) a liquid composition A, preferably dispersion A, comprising a conductive polymer and a dispersant, wherein a conductive layer made from liquid composition A has a conductivity of less than 100 S / cm, preferably less than 25 S / cm, more preferably less than 10 S / cm, even more preferably less than 4 S / cm, and most preferably less than 1 S / cm; or ii) a liquid composition B, preferably dispersion B, comprising a conductive polymer and a dispersant, wherein liquid composition B comprises less than 3% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, even more preferably less than 0.1% by weight and most preferably less than 0.01% by weight of a high-boiling solvent, in each case based on the total weight of liquid composition B, the high-boiling solvent having a boiling point (measured at 1013 hPa) of at least 150° C., preferably at least 170° C., more preferably at least 185° C., and it is particularly preferred that liquid composition B is essentially free, preferably free, of high-boiling solvents, or iii) a liquid composition C, preferably a dispersion C, comprising a conductive polymer and a dispersant, wherein the liquid composition C comprises less than 3% by weight, preferably less than 1% by weight, more preferably less than 0.5% by weight, even more preferably less than 0.1% by weight and most preferably less than 0.01% by weight of a high-boiling solvent, in each case based on the total weight of the liquid composition C, the high-boiling solvent having a boiling point (measured at 1013 hPa) of at least 150°C, preferably at least 170°C, more preferably at least 185°C, and wherein a conductive layer made from the liquid composition C has a conductivity of less than 100 S / cm, preferably less than 25 S / cm, more preferably less than 10 S / cm, even more preferably less than 4 S / cm and most preferably less than 1 S / cm, and it is particularly preferred that the liquid composition C is essentially free, preferably free, of high-boiling solvents, introducing into at least a portion of the porous electrode body provided in process step a), c) at least partially removing the dispersant from the porous electrode body obtained in process step b) to form a solid electrolyte layer at least partially covering the surface of the dielectric; d) filling at least some of the pores of the porous electrode body obtained in process step c) with an impregnation solution comprising at least one impregnation solvent, the at least one impregnation solvent having a boiling point (measured at 1013 hPa) of at least 150°C, preferably at least 170°C, more preferably at least 190°C, e) encapsulating the porous electrode body obtained in process step d), wherein it is preferred that less than 20% by weight, preferably less than 10% by weight, more preferably less than 1% by weight of the impregnation solution used in process step d) to fill a portion of the pores of the porous electrode body evaporates before encapsulating the porous electrode body, and it is even more preferred that essentially the entire amount, most preferably the entire amount, of the impregnation solution used in process step d) to fill a portion of the pores of the porous electrode body remains in the porous electrode body before it is encapsulated, A contribution to the solution is made by a first embodiment of the manufacturing process, comprising: f) heating the encapsulated electrode body obtained in process step e) at a temperature above 50°C, more preferably above 75°C, even more preferably above 100°C, for a period of more than 10 minutes, preferably more than 20 minutes, more preferably more than 30 minutes.

[0012] As used herein, the term "high-boiling solvent having a boiling point of at least 150° C. (measured at 1013 hPa)" preferably refers to a compound that actually boils (i.e., changes its state of aggregation from a liquid state to a gaseous state) at a temperature of at least 150° C. The term preferably does not include compounds that do not actually boil, but that decompose at high temperatures and then boil (such as polyethylene glycol 400).

[0013] The combination of process steps b) and c) can be carried out only once or can be repeated several times, for example 2, 3, 4, 5, 6, 7, 8, 9 or at least 10 times.

[0014] According to a first most preferred variant of the process according to the invention, in process step b), a liquid composition A, preferably a dispersion A, is introduced into at least a portion of the porous electrode body provided in process step a). In this connection, it is also preferred that the conductive layer made from liquid composition A has a conductivity of 0.1 S / cm or more, preferably 0.2 S / cm or more. Preferably, the conductive layer made from liquid composition A has a conductivity in the range of 0.1 S / cm to less than 10 S / cm, even more preferably in the range of 0.1 S / cm to less than 4 S / cm, most preferably in the range of 0.1 S / cm to less than 1 S / cm.

[0015] According to a second variant of the process according to the invention, in process step b), a liquid composition B, preferably a dispersion B, is introduced into at least part of the porous electrode body provided in process step a).

[0016] According to a third variant of the process according to the invention, in process step b), a liquid composition C, preferably a dispersion C, is introduced into at least a portion of the porous electrode body provided in process step a). In this connection, it is also preferred that the conductive layer made from liquid composition C has a conductivity of at least 0.1 S / cm, preferably at least 0.2 S / cm. Preferably, the conductive layer made from liquid composition C has a conductivity in the range of 0.1 S / cm to less than 10 S / cm, even more preferably in the range of 0.1 S / cm to less than 4 S / cm, most preferably in the range of 0.1 S / cm to less than 1 S / cm.

[0017] The liquid composition A, B, or C used in process step b) can be in the form of a solution or dispersion. However, the transition here can be fluid. Therefore, hereinafter, no distinction is made between the terms "dispersed" and "dissolved." Similarly, no distinction is made between "dispersion" and "solution" or between "dispersant" and "solvent." Rather, these terms are used interchangeably. However, the liquid composition A, B, or C is preferably in the form of a dispersion in which the conductive polymer is dispersed in the dispersant.

[0018] |2a| According to a preferred embodiment of the process according to the invention, the electrode material is aluminum and the dielectric is aluminum oxide, preferably Al2O3. This preferred embodiment is a second embodiment of the method according to the invention, which is preferably dependent on the first embodiment.

[0019] |3a| According to a further preferred embodiment of the process according to the invention, the liquid composition A, B or C used in process step b), preferably liquid composition A, comprises particles of a conductive polymer. In this context, the particles have a diameter d in the range of 1 to 100 nm, preferably in the range of 1 to less than 70 nm, preferably in the range of 1 to 50 nm, particularly preferably in the range of 1 to 40 nm, more particularly preferably in the range of 5 to 30 nm. 50It is particularly preferred that the particle diameter is determined by ultracentrifugation. This preferred embodiment is a third embodiment of the method according to the invention, which is preferably dependent on the first or second embodiment.

[0020] According to a further preferred embodiment of the process according to the invention, the conductive polymer comprises at least one polymer selected from the group consisting of polythiophene, polypyrrole, polyaniline, and a mixture of at least two thereof. This preferred embodiment is the fourth embodiment of the process according to the invention, and preferably depends from any one of the first to third embodiments.

[0021] |5a| According to a further preferred embodiment of the process according to the invention, the conductive polymer is poly(3,4-ethylenedioxythiophene) or a derivative thereof. This preferred embodiment is a fifth embodiment of the process according to the invention, which preferably depends from any one of the first to fourth embodiments.

[0022] According to a further preferred embodiment of the process according to the invention, the liquid compositions A, B or C used in process step b), preferably liquid composition A, further comprise at least one polymeric anion. This preferred embodiment is the sixth embodiment of the process according to the invention, which is preferably dependent on any one of the first to fifth embodiments.

[0023] |7a| According to a further preferred embodiment of the process according to the invention, the polymer anion is polystyrene sulfonic acid or a derivative thereof. In this connection, it is particularly preferred that the conductive polymer in liquid composition A, B or C, preferably liquid composition A, used in process step b) is present in the form of a polythiophene / (poly)anion complex, the polythiophene being poly(3,4-ethylenedioxythiophene) and the polyanion being the anion of polystyrene sulfonic acid. This preferred embodiment is a seventh embodiment of the process according to the invention, which is preferably subordinate to the sixth embodiment.

[0024] |8a| According to a further preferred embodiment of the process according to the invention, liquid composition A, B or C, preferably liquid composition A, used in process step b) has a pH value (measured at 25°C) in the range from 2.5 to 8.0, preferably in the range from 2.5 to 7, more preferably in the range from 3 to 6. This preferred embodiment is an eighth embodiment of the process according to the invention, which is preferably dependent on any one of the first to seventh embodiments.

[0025] According to a further preferred embodiment of the process according to the invention, in process step d), at least 25% by volume of the open pore volume of the porous electrode body obtained in process step c) is filled with the impregnation solution, more preferably at least 30% by volume, even more preferably at least 40% by volume, even more preferably at least 50% by volume, even more preferably at least 75% by volume, and most preferably at least 90% by volume. This preferred embodiment is a ninth embodiment of the process according to the invention, which is preferably dependent on any one of the first to eighth embodiments.

[0026] According to a further preferred embodiment of the process according to the invention, the impregnation solution used in process step d) has an ionic conductivity of less than 1000 μS / cm, preferably less than 100 μS / cm, even more preferably less than 10 μS / cm, most preferably less than 1 μS / cm. This preferred embodiment is a tenth embodiment of the process according to the invention, which is preferably dependent on any one of the first to ninth embodiments.

[0027] According to a further preferred embodiment of the process according to the invention, the impregnation solution used in process step d) comprises a mixture of at least two impregnation solvents. This preferred embodiment is an eleventh embodiment of the process according to the invention, which is preferably dependent on any one of the first to tenth embodiments.

[0028] |12a| According to a further preferred embodiment of the process according to the invention, the impregnation solution used in process step d) comprises at least one impregnation solvent in an amount of at least 50% by weight, preferably at least 75% by weight, even more preferably at least 90% by weight, and most preferably at least 95% by weight, in each case based on the total weight of the impregnation solution. In the case of two or more impregnation solvents, these amounts refer to the total amount of impregnation solvents. This preferred embodiment is a twelfth embodiment of the process according to the invention, which is preferably dependent on any one of the first to eleventh embodiments.

[0029] |13a| According to a further preferred embodiment of the process according to the invention, at least one impregnation solvent in the impregnation solution used in process step d) has a melting point below 15° C., preferably below 5° C., even more preferably below −5° C. This preferred embodiment is a thirteenth embodiment of the process according to the invention, which is preferably dependent on any one of the first to twelfth embodiments.

[0030] |14a| According to a further preferred embodiment of the process according to the invention, at least one impregnation solvent in the impregnation solution used in process step d) has a boiling point (measured at 1013 hPa) of at least 200° C. and below 330° C. This preferred embodiment is a 14th embodiment of the process according to the invention, which is preferably dependent on any one of the 1st to 13th embodiments.

[0031] |15a| According to a further preferred embodiment of the process according to the invention, at least one impregnation solvent in the impregnation solution used in process step d) contains at least one hydroxy group and has a molecular weight in the range of 70 to 195 g / mol, preferably 70 to 180 g / mol. In this context, it is further preferred that at least one impregnation solvent in the impregnation solution used in process step d) is a compound containing two hydroxy groups or a compound containing one hydroxy group and one ether group, preferably one alkyl ether group. This preferred embodiment is a 15th embodiment of the process according to the invention, which preferably depends from any one of the first to fourteenth embodiments.

[0032] According to a further preferred embodiment of the process according to the invention, at least one impregnation solvent in the impregnation solution used in process step d) is a compound containing two hydroxy groups or a compound containing one hydroxy group and one ether group, preferably one alkyl ether group, with polyglycols having 2 to 4 repeating units being particularly preferred as impregnation solvents. This preferred embodiment is a 16th embodiment of the process according to the invention, which is preferably dependent on any one of the 1 to 15 embodiments.

[0033] According to a further preferred embodiment of the process according to the invention, at least one impregnation solvent in the impregnation solution used in process step d) is selected from the group consisting of diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures of at least two thereof, with diethylene glycol and triethylene glycol being particularly preferred. This preferred embodiment is a 17th embodiment of the process according to the invention, which is preferably dependent on any one of the 1 to 16 embodiments.

[0034] |18a| According to a further preferred embodiment of the process according to the invention, the liquid composition A, B, or C used in process step b), preferably liquid composition A, the impregnation solution used in process step d), or both, preferably the impregnation solution used in process step d), further comprises a stabilizer. This preferred embodiment is the 18th embodiment of the process according to the invention, preferably dependent on any one of the first to seventeenth embodiments. Preferred stabilizers are the compounds mentioned in WO 2012 / 041507 A1, with aromatic compounds containing at least two OH groups and one additional functional group having a heteroatom different from carbon being particularly preferred. Examples of suitable stabilizers are 3,4,5-trihydroxybenzoic acid and its derivatives, such as 3,4,5-trihydroxybenzoic acid esters (gallic acid esters), in particular alkyl esters, alkenyl esters, cycloalkyl esters, cycloalkenyl esters, and aryl esters, preferably having 1 to 15 C atoms in each case in the aryl or alkyl group of the ester. Particularly preferred are gallic acid and sugar-esterified gallic acid, often referred to as tannins or gallotannins (see Rompp Chemie, 10th Edition (1999), p. 4391). Suitable stabilizers include the "hydroxyl-containing aromatic compounds" mentioned in paragraph

[0049] of EP 1 798 259 A1, the "antioxidants" mentioned in paragraph

[0025] of EP 1 043 720 A1, and the "aromatic compounds containing at least two hydroxyl groups, excluding sulfo groups" mentioned on pages 10 and 11 of WO 2008 / 055834 A1. In this context, it is also preferred to use stabilizers in concentrations ranging from 0.1% to 60% by weight, preferably from 1% to 25% by weight, and particularly preferably from 2% to 10% by weight, based on the total weight of the impregnation solution. If the liquid composition A, B or C used in process step b), preferably liquid composition A, comprises a stabilizer, it is preferred to use the stabilizer in a concentration in the range of 0.1% to 20% by weight, preferably in the range of 0.5% to 10% by weight, particularly preferably in the range of 1% to 5% by weight, based on the total weight of the liquid composition.

[0035] |19a| According to a further preferred embodiment of the process according to the invention, the process does not comprise a process step in which at least a portion of the impregnation solution comprising at least one impregnation solvent having a boiling point (measured at 1013 hPa) of at least 150°C, preferably at least 170°C, more preferably at least 190°C, used to fill at least a portion of the pores of the porous electrode body is removed before the porous electrode body is encapsulated in process step e). This preferred embodiment is a 19th embodiment of the process according to the invention, which is preferably dependent on any one of the 1 to 18 embodiments.

[0036] |1b| A contribution to solving at least one of the objects according to the invention is made by a first embodiment of a capacitor which can be obtained, preferably obtained, by a process according to the invention, preferably by a process according to any one of the first to nineteenth embodiments.

[0037] |2b| According to a further preferred embodiment of the capacitor 1 according to the invention, the capacitor has a rated voltage in the range of 1 to 250 V, preferably in the range of 6 to 100 V, more preferably in the range of 10 to 63 V. This preferred embodiment is a second embodiment of the capacitor 1 according to the invention, which is preferably dependent on the first embodiment.

[0038] |1c| A contribution to solving at least one of the objects according to the invention is made by the use of a capacitor according to the first or second embodiment in an electronic circuit, for example as a smoothing capacitor ("filter capacitor") or as a suppression capacitor ("decoupling capacitor"). The electronic circuit can be found, for example, in computers (desktop, laptop, server), in computer peripheral devices (for example PC cards), in portable electronic devices such as mobile phones, digital cameras, chargers or consumer electronics, in consumer electrical equipment such as CD / DVD players and computer game consoles, in navigation systems, in long-range communication devices such as base stations for mobile communications, in household appliances in medical technology such as defibrillators, in power supplies such as those based on renewable energy or in power supplies for automotive electronics such as hybrid or electric vehicles.

[0039] |1d| A contribution to solving at least one of the objects according to the invention is made by an electronic circuit comprising a capacitor according to the first or second embodiment.

[0040] Process step a) In process step a) of the process according to the invention, a porous electrode body made of an electrode material is provided, the dielectric at least partially covering the surface of this electrode material.

[0041] In principle, a porous electrode body can be manufactured by compressing and sintering a valve metal powder having a large surface area to form the porous electrode body. In this regard, an electrical contact wire, preferably made of a valve metal such as tantalum, is conventionally compressed into the porous electrode body. The porous electrode body is then coated with a dielectric, i.e., an oxide layer, for example, by electrochemical oxidation. Alternatively, to obtain an anode film with a porous region, a metal film can be etched and coated with a dielectric by electrochemical oxidation. In the case of a wound capacitor, the anode film and cathode film with a porous region that form the electrode body are separated by a separator and wound.

[0042] Within the scope of the present invention, metals whose oxide coatings do not allow current to flow uniformly in both directions are considered valve metals. When a voltage is applied to the anode, the oxide layer of the valve metal blocks the flow of current, while when a voltage is applied to the cathode, a large amount of current is generated, which may destroy the oxide layer. Valve metals include Be, Mg, Al, Ge, Si, Sn, Sb, Bi, Ti, Zr, Hf, V, Nb, Ta, and W, as well as alloys or compounds of at least one of these metals with other elements. The most well-known representatives of valve metals are Al, Ta, and Nb. Combinations of electrical properties equivalent to valve metals have metallic conductivity and can be oxidized, resulting in an oxide layer that provides these properties. For example, NbO exhibits metallic conductivity but is generally not considered a valve metal. However, an oxidized NbO layer exhibits typical properties of a valve metal oxide layer, and as a result, NbO or an alloy or compound of NbO is a typical example of a compound with electrical properties equivalent to a valve metal. Electrode materials made of tantalum, aluminum, and electrode materials based on niobium or niobium oxide are preferred, with aluminum being particularly preferred as the electrode material.

[0043] To produce a porous electrode body, which often has porous regions, the valve metal can be sintered, for example, in powder form to provide a generally porous electrode body, or alternatively, the porous structure can be imprinted onto the metal body, the latter of which can be done, for example, by etching the film.

[0044] Hereinafter, for simplicity, a body having a porous region will also be referred to as porous. For example, an electrode body having a porous region will also be referred to as porous electrode body. On the one hand, a porous body can be perforated with multiple channels and therefore has a sponge-like structure. This is often the case when tantalum is used to construct a capacitor. On the other hand, pores can only be present on the surface, and the region located below the surface pores can be solid. This is often observed when aluminum is used in capacitor construction.

[0045] The porous electrode body thus produced is then oxidized by applying a voltage, for example in a suitable electrolyte, such as an aqueous solution of phosphoric acid or ammonium adipate, to form a dielectric. The magnitude of this formation voltage depends on the thickness of the oxide layer to be achieved and, correspondingly, on the subsequent operating voltage of the capacitor. Preferred formation voltages are in the range of 1 to 1000 V, particularly preferably in the range of 10 to 200 V, more particularly preferably in the range of 15 to 100 V, and more preferably in the range of 20 to 50 V.

[0046] The porous electrode body used preferably has a porosity of 10 to 90%, preferably 30 to 80%, particularly preferably 50 to 80% and an average pore diameter of 10 to 10000 nm, preferably 50 to 5000 nm, particularly preferably 100 to 3000 nm.

[0047] According to a particular embodiment of the process of the present invention, the electrolytic capacitor to be manufactured is an aluminum-wound capacitor. In this case, in process step a), a porous aluminum film as the electrode material is applied to the anode, whereby an aluminum oxide coating is applied as the dielectric. The aluminum film thus obtained (anode film) is then provided with a contact wire and wound around it, and a further porous aluminum film (cathode film) is also provided with a contact wire, with these two films being separated from each other by one or more separator papers, for example, based on cellulose or preferably synthetic paper. After winding, the thus obtained anode body is fixed, for example, with adhesive tape. The separator paper can be carbonized by heating in an oven. Methods for manufacturing anode bodies for aluminum-wound capacitors are well known in the prior art and are described, for example, in U.S. Pat. No. 7,497,879 (B2).

[0048] Process steps b) and c) In process step b) of the process according to the invention, liquid composition A, B or C as described in connection with the first embodiment of the process according to the invention, preferably liquid composition A (hereinafter simply referred to as liquid composition), preferably in the form of a dispersion comprising a conductive polymer and a dispersing agent, is introduced into at least a portion of the porous electrode body provided in process step a). Then, in process step c), the dispersing agent is at least partially removed to form a solid electrolyte at least partially covering the surface of the dielectric.

[0049] The liquid composition is introduced into the porous region using known processes, such as immersion, dipping, pouring, dripping, injecting, spraying, spreading, painting, or printing, such as inkjet printing, screen printing, or pad printing. The introduction is preferably carried out by immersing the porous electrode body provided in process step a) into the liquid composition and impregnating it accordingly with this liquid composition. The immersion or impregnation into the liquid composition is preferably carried out for a duration ranging from 1 second to 120 minutes, particularly preferably from 10 seconds to 60 minutes, and most preferably from 30 seconds to 15 minutes. The introduction of the liquid composition into the anode body can be facilitated, for example, by increasing or decreasing pressure, vibration, ultrasound, or heat.

[0050] The liquid composition can be introduced into the porous electrode body directly or with the aid of an adhesion promoter, e.g., a silane such as an organofunctional silane or a hydrolyzate thereof, e.g., 3-glycidoxy-propyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyl-trimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, or octyltriethoxysilane, and / or one or more other functional layers.

[0051] By introducing the liquid composition, it is preferably achieved that the liquid composition tends to cover the pores of the porous region to a lesser extent with a layer. To be precise, the surfaces of the pore cavities are at least partially coated with the liquid composition. In this way, not only do the particles present in the liquid composition form a layer that covers the openings of the pores, but at least a portion of the surface of the pores, and in many cases even the entire area, is covered with a layer of particles of the liquid composition.

[0052] The term "polymer", as used within the scope of the present invention, includes all compounds within the realization of the present invention having two or more identical or different repeating units.

[0053] The term "conductive polymer" as used herein refers specifically to a class of compounds, π-conjugated polymers, that have electrical conductivity after oxidation or reduction.

[0054] The conductive polymer in the liquid composition is preferably selected from the group consisting of optionally substituted polythiophenes, polypyrroles, and polyanilines.

[0055] Particularly preferably, the conductive polymer comprises a polythiophene having repeating units selected from the group consisting of general formula (I), general formula (II), or general formula (III), or a combination of at least two thereof. In the following possible variant, the conductive polymer in the dispersion comprises at least one polythiophene having repeating units of general formula (I), general formula (II), or general formula (III), or repeating units of formulas (I) and (II), or repeating units of formulas (I) and (III), or repeating units of formulas (II) and (III), or repeating units of formulas (I), (II), and (III).

[0056] [ka] (In the formula, A represents an optionally substituted C1-C5-alkylene residue, R is a straight or branched chain optionally substituted C-C18 -Alkyl residue, optionally substituted C5-C 12 -cycloalkyl residue, optionally substituted C-C 14 -aryl residue, optionally substituted C7-C 18 - represents an aralkyl residue, an optionally substituted C1-C4-hydroxyalkyl residue or a hydroxyl residue, x represents an integer of 0 to 8, If several residues R are attached to A, they may be the same or different).

[0057] General formulas (I) and (II) should be understood such that x substituents R can be attached to the alkylene residue.

[0058] Particularly preferred are polythiophenes having repeating units of the general formula (I) or (II) or repeating units of the general formulae (I) and (II), where A represents an optionally substituted C2-C3-alkylene residue and x represents 0 or 1. Optionally substituted poly(3,4-ethylenedioxythiophene) is very particularly preferred as the conductive polymer of the solid electrolyte.

[0059] Within the framework of the present invention, the prefix "poly" is understood to mean that two or more identical or different repeating units are contained in the polymer or polythiophene. Polythiophenes contain a total of n repeating units of general formula (I) or (II) or (III), or general formulas (I) and (II), or general formulas (I) and (III), or general formulas (II) and (III), or general formulas (I), (II), and (III), where n is an integer from 2 to 2000, preferably from 2 to 100. The repeating units of general formula (I) or general formula (II) or general formula (III), or the repeating units of general formulas (I) and (II), or the repeating units of general formulas (I) and (III), or the repeating units of general formulas (II) and (III), or the repeating units of general formulas (I), (II), and (III), may be identical or different in each instance within one polythiophene. Polythiophenes having the same repeating units of general formula (I), (II), or (III), or the same repeating units of general formulas (I and II), or the same repeating units of general formulas (I and III), or the same repeating units of general formulas (II) and (III), or the same repeating units of general formulas (I), (II), and (III) are preferred. Polythiophenes having the same repeating units of general formula (I) or (II), or the same repeating units of general formulas (I and II), are particularly preferred.

[0060] The polythiophene preferably has an H at each end group.

[0061] Within the scope of the present invention, the C1-C5-alkylene residue A is preferably methylene, ethylene, n-propylene, n-butylene or n-pentylene. 18The alkyl residue R is preferably a linear or branched C-C alkyl group such as methyl, ethyl, n- or isopropyl, 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. 18 - denotes alkyl residues, C5-C 12 - the cycloalkyl residue R denotes, for example, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or cyclodecyl, C5-C 14 the aryl residue R denotes, for example, phenyl or naphthyl, and C7-C 18 -Aralkyl residue R denotes, 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 is provided for the purposes of exemplary illustration of the invention and should not be considered as exclusive.

[0062] As optional further substituents of residue A and / or residue R, numerous organic groups are considered within the scope of the present invention, such as alkyl groups, cycloalkyl groups, aryl groups, aralkyl groups, alkoxy groups, halogen groups, ether groups, thioether groups, disulfide groups, sulfoxide groups, sulfone groups, sulfonate groups, amino groups, aldehyde groups, keto groups, carboxylic ester groups, carboxylic acid groups, carbonate groups, carboxylate groups, cyano groups, alkylsilane groups, and alkoxysilane groups, as well as carboxylamide groups.

[0063] The above-listed residues A and R and / or further substituents of residues A and R come into consideration, for example, as substituents of polyaniline or polypyrrole. Unsubstituted polyaniline is preferred.

[0064] The scope of the present invention includes all of the general residue definitions, parameters, and descriptions presented above and listed below, or listed in the preferred ranges, together with each other, i.e., in any combination between the respective ranges and preferred ranges.

[0065] The polythiophenes used in the preferred process as solid electrolytes can be neutral or cationic. In preferred embodiments, they are cationic, with "cationic" referring only to the charge provided on the main polythiophene chain. Depending on the substituents on the residues, polythiophenes can carry positive and negative charges within the structural units, with the positive charge located on the main polythiophene chain and the negative charge located on the residue R, which is optionally substituted by a sulfonate or carboxylate group. Thus, the positive charge of the polythiophene main chain can be partially or completely compensated by an anionic group optionally present on the residue R. Generally, in these cases, the polythiophene can be cationic, neutral, or even anionic. However, within the scope of the present invention, all polythiophenes are considered cationic polythiophenes, since the positive charges on the main polythiophene chain are clearly important. The positive charges are not shown in the formula because their exact number and location cannot be precisely determined. However, the number of positive charges is at least 1 and at most n, where n represents the total number of all repeat units (same or different) within the polythiophene.

[0066] To compensate for the positive charge, cationic polythiophenes require anions as counterions, provided that this is not already done through optionally sulfonate- or carboxylate-substituted and therefore negatively charged residues R.

[0067] The counterions can be monomeric or polymeric anions, the latter hereinafter also referred to as polyanions. Polymeric anions are preferred over monomeric anions because they contribute to film formation and, due to their size, result in thermally more stable conductive films.

[0068] The polymeric anions herein can be, for example, the anions of polymeric carboxylic acids, such as polyacrylic acid, polymethacrylic acid, or polymaleic acid, or polymeric sulfonic acids, such as polystyrene sulfonic acid and polyvinyl sulfonic acid. These polycarboxylic and polysulfonic acids can also be copolymers of vinyl carboxylic and vinyl sulfonic acids with other polymerizable monomers, such as acrylic esters and styrene.

[0069] Anions of polymeric carboxylic or sulfonic acids in the particles mentioned are preferred as polymeric anions.

[0070] Particularly preferred as polymer anions are poly(3,4-ethylenedioxythiophene) complexed with polystyrene sulfonic acid (PSS), which is present in the use of polythiophenes, and in particular the anions of poly(3,4-ethylenedioxythiophene) known from the prior art, preferably in the form of a PEDOT / PSS complex. Such complexes can be obtained by oxidative polymerization of thiophene monomers, preferably 3,4-ethylenedioxythiophene, in aqueous solution in the presence of polystyrene sulfonic acid.

[0071] The molecular weight of the polyacid providing the polyanion is preferably 1,000 to 2,000,000, particularly preferably 2,000 to 500,000. Polyacids or their alkali salts are commercially available, for example, polystyrene sulfonic acid and polyacrylic acid, but can also be produced using known processes (see, for example, Houben Weyl, Methoden der organischen Chemie, Vol. E20 Makromolekulare Stoffe, Part 2, (1987), [Methods of Organic Chemistry, Macromolecular Substances], p. 1141 et seq.).

[0072] The polymeric anion and the conductive polymer may be present in the liquid composition in a weight ratio of, in particular, 0.5:1 to 50:1, preferably 1:1 to 30:1, particularly preferably 1.5:1 to 20:1, where the weight of the conductive polymer corresponds to the weighed amount of the monomers used, assuming complete conversion during polymerization.

[0073] As the monomer anion, for example, C1-C 20 Alkanesulfonic acids, such as methane-, ethane-, propane-, butane-, or higher sulfonic acids, such as dodecanoic acid sulfonic acid; aliphatic perfluorosulfonic acids, such as trifluoromethanesulfonic acid, perfluorobutanesulfonic acid, or perfluorooctanesulfonic acid; aliphatic C1-C 20 Carboxylic acids, such as 2-ethylhexylcarboxylic acid, aliphatic perfluorocarboxylic acids, such as trifluoroacetic acid or perfluorooctanoic acid, and C-C 20 Aromatic sulfonic acids, optionally substituted with alkyl groups, such as benzenesulfonic acid, o-toluenesulfonic acid, p-toluenesulfonic acid, or dodecylbenzenesulfonic acid, and cycloalkanesulfonic acids, such as camphorsulfonic acid, or monomeric onions of tetrafluoroborate, hexafluorophosphate, perchlorate, hexafluoroantimonate, hexafluoroarsenate, or hexachloroantimonate, can be used. The anions of p-toluenesulfonic acid, methanesulfonic acid, or camphorsulfonic acid are preferred as monomeric anions.

[0074] Cationic polythiophenes contain anions as counterions for charge compensation and are often referred to in specialist circles as polythiophene / (poly)-anion complexes.

[0075] Also suitable as polythiophenes that can be used to form the solid electrolyte layer in process steps b) and c) are self-doped polythiophenes, which preferably comprise repeat units of formula (I) to an extent of at least 50%, even more preferably to an extent of at least 75%, even more preferably to an extent of at least 95%, and most preferably to an extent of 100%.

[0076] [ka] [In the formula, X and Y are the same or different and are O, S, NR 1 indicates R 1 is C1-C 18 - represents alkyl or hydrogen, Z is at least an anionic substituent, preferably -SO3 - M + represents an organic residue having a group, and M + indicates a cation].

[0077] According to a preferred embodiment of the repeat unit of formula (I): Z is -(CH2) m -CR 2 R 3 -(CH2) n - indicates (In the formula, R 2 is hydrogen, -(CH2) s -O-(CR 4 2) p -SO3 - M + , or -(CH2) p -SO3 - Indicates M, R 3 is -(CH2) s -O-(CR 4 2) p -SO3 - M + , or -(CH2) p -SO3 - M + indicates, m and n are the same or different and represent an integer of 0 to 3, R 4 is hydrogen or C1-C 10 represents an alkyl group, preferably a methyl group, s represents an integer from 0 to 10, p represents an integer of 1 to 18; In the above formula, R 1 , R 2 , R 3 , and R 4 may be the same or different).

[0078] The above percentage values ​​are in this context intended to represent the numerical content of units of structural formula (I) in the total number of monomer units in the self-doped conductive polymer.

[0079] Suitable cations M + For example, H + , Li + , Na + , K. + , Rb + , Cs + , and NH4 + A particularly preferred cation is Na + and K. + is.

[0080] Particularly preferred monomers of formula (I) are X and Y represent O, Z is -(CH2) m -CR 2 R 3 -(CH2) n - indicates R 2 is hydrogen or -(CH2) s -O-(CH2) p -SO3 - M + , -(CH2) p -SO3 - M + , or -(CH2) s -O-(CH2) p -CHR 4 -SO3 - M+ indicates, R 3 is -(CH2) s -O-(CH2) p -SO3 - M + , -(CH2) p -SO3 - M + , or -(CH2) s -O-(CH2) p -CHR 4 -SO3 - M + indicates, M + indicates a cation, m and n are the same or different and represent an integer of 0 to 3, R 4 represents hydrogen, a methyl group, or an ethyl group; s represents an integer from 0 to 10, p represents an integer of 1 to 18;

[0081] Highly preferred monomers of structural formula (I) are X and Y represent O, Z is -(CH2)-CR 2 R 3 -(CH2) n - indicates R 2 indicates hydrogen, R 3 is -(CH2) s -O-(CH2) p -SO3 - M + , -(CH2) p -SO3 - M + , -(CH2) s -O-(CH2) p -CH(CH3)-SO3 - M + , or -(CH2) s -O-(CH2) p -CH(CH2CH3)-SO3 - M + indicates, M + Na + or K+ indicates, n represents 0 or 1; s represents 0 or 1, p represents 2, 3, 4, or 5.

[0082] Suitable examples of self-doping polymers that can also be used to form the solid electrolyte layer in process steps b) and c) are disclosed in WO 2014 / 048562A and U.S. Patent Application Publication No. 2015 / 0337061A. Specific examples of very particularly preferred self-doping conductive polymers include poly(4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]propane-1-sulfonic acid), poly(4-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]butane-1-sulfonic acid) (PEDOT-S), poly(4-[(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)methoxy]butane-2-sulfonic acid), or mixtures thereof.

[0083] Preferably, the conductive polymer in the liquid composition used in process step b) is in the form of particles, particularly preferably in the form of swollen gel particles of a polythiophene / (poly)-anion complex, such as PEDOT / PSS. The particles preferably have a specific conductivity of less than 100 S / cm. The specific conductivity of the particles in this context is the specific conductivity of the dry film formed from the particles upon drying of the dispersion. Preferably, a liquid composition is used, the particles of which have a specific conductivity of less than 25 S / cm, more preferably less than 10 S / cm, even more preferably less than 4 S / cm, and most preferably less than 1 S / cm. In this context, it is also preferred that the particles have a specific conductivity of 0.1 S / cm or more, preferably 0.2 S / cm or more. Most preferably, the particles have a specific conductivity in the range of 1 S / cm to less than 10 S / cm, even more preferably in the range of 0.1 S / cm to less than 4 S / cm, and most preferably in the range of 0.1 S / cm to less than 1 S / cm.

[0084] If the conductive polymer in the liquid composition used in process step b) is present in the form of particles, the particles preferably have a diameter d in the range of 1 to 100 nm, preferably in the range of 1 to 70 nm, preferably in the range of 1 to 50 nm, particularly preferably in the range of 1 to 40 nm and more particularly preferably in the range of 5 to 30 nm. 50 The particle diameter is determined by ultracentrifuge measurement. The particles of the conductive polymer in the liquid composition have a diameter of less than 150 nm, particularly preferably less than 100 nm, more particularly preferably less than 50 nm. 90 It is further preferred that the particles of the conductive polymer in the liquid composition have a diameter distribution of d greater than 1 nm, particularly preferably greater than 3 nm, more particularly preferably greater than 5 nm. 10 It has a diameter distribution of values.

[0085] The liquid composition used in process step b) preferably comprises the purity with respect to metals and transition metals as set out in the published document 2010 / 003874(A2) on page 6, lines 10 to 29. The low concentration of metals in the liquid composition has the major advantage that the dielectric is not damaged during the formation of the solid electrolyte and during the subsequent operation of the capacitor.

[0086] The liquid composition used in process step b) further comprises at least one dispersant, with water, an organic solvent or a mixture of an organic solvent and water being preferred as dispersant.

[0087] The following solvents can be mentioned as examples of dispersants: aliphatic alcohols such as methanol, ethanol, i-propanol, and butanol; aliphatic ketones such as acetone and methyl ethyl ketone; aliphatic carboxylic acid esters such as acetic acid ester and acetic acid butyl ester; aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane, heptane, and cyclohexane; chlorinated hydrocarbons such as dichloromethane and dichloroethane; aliphatic nitriles such as acetonitrile, aliphatic sulfoxides and sulfones such as dimethyl sulfoxide and sulfolane; aliphatic carboxylic acid amides such as methylacetamide, dimethylacetamide, and dimethylformamide, aliphatic and araliphatic ethers such as diethyl ether and anisole. Furthermore, water or a mixture of water and the above organic solvents can also be used as the dispersant.

[0088] Preferred dispersants are water or other protic solvents such as alcohols, for example, methanol, ethanol, i-propanol, and butanol, as well as mixtures of water with these alcohols. A particularly preferred dispersant is water.

[0089] The liquid composition used in process step b) can further comprise additional components such as surface-active substances, for example, organofunctional silanes or their hydrolysates, such as ionic and nonionic surfactants or adhesion promoters, such as 3-glycidoxypropyltrialkoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, or octyltriethoxysilane, melamine compounds, blocked isocyanates, crosslinking agents such as functional silanes—for example, epoxy silanes, such as tetraethoxysilane, alkoxysilane hydrolysates, for example, those based on tetraethoxysilane, 3-glycidoxypropyltrialkoxysilane-polyurethane, polyacrylate, or polyolefin dispersions. The liquid composition used in process step b) can also comprise one or more organic binders soluble in organic solvents, as described on page 12, lines 16-34 of WO 2009 / 141209 A1. The liquid composition may have a pH value of 1 to 14, with a pH value of 1 to 8 being preferred. For corrosion-sensitive dielectrics such as aluminum oxide or niobium oxide, a liquid composition having a pH value of 2.5 to 8, more preferably 2.5 to 7, and most preferably 3 to 6 is preferred to avoid damage to the dielectric.

[0090] To adjust the pH value, for example, bases or acids described in WO 2010 / 003874(A2) on page 4, lines 13 to 32 can be added to the liquid composition. Preferred additives that do not impair the film formation of the liquid composition and are not volatile at relatively high temperatures, for example at soldering temperatures, but remain in the solid electrolyte under these conditions include, for example, the bases 2-dimethylaminoethanol, 2,2'-iminodiethanol, or 2,2',2''-nitrilotriethanol and the acid polystyrene sulfonic acid.

[0091] The viscosity of the liquid composition used in process step b) can be between 0.1 and 1000 mPa × s (at 20 °C and 100 s), depending on the application process. -1(Measured with a rheometer at a shear rate of 1000 kJ / s). Preferably, the viscosity is 1 to 200 mPa×s, particularly preferably 10 to 150 mPa×s, and even more particularly preferably 10 to 100 mPa×s.

[0092] The solids content of the liquid composition used in process step b) is preferably in the range of 1 to 30% by weight, particularly preferably in the range of 1 to 20% by weight, most preferably in the range of 1 to 10% by weight, in each case based on the total weight of the liquid composition. The solids content is determined by drying the dispersion at a temperature high enough to remove the dispersant but not to decompose the solid material.

[0093] After impregnation of the porous electrode body with the liquid composition, the dispersant is at least partially removed in process step c) to form a solid electrolyte layer which partially or completely covers the dielectric. In this connection, the coverage of the dielectric by the solid electrolyte layer preferably reaches at least 50%, particularly preferably at least 70%, most preferably at least 80%, and measurement of the capacitance of the capacitor under dry and wet conditions at 120°C allows the determination as described in DE 10 2005 043 828 (A).

[0094] The removal of the dispersant is preferably carried out by removing the porous electrode body from the liquid composition used in process step b) and subsequently drying, the drying being preferably carried out at a temperature in the range of 20°C to 200°C, particularly preferably in the range of 50°C to 180°C, and more preferably in the range of 80°C to 150°C. The drying conditions (i.e., drying time, drying pressure, and drying temperature) are preferably adjusted so as to be within a range that ensures the removal of at least 50% by weight, more preferably at least 75% by weight, even more preferably at least 90% by weight, even more preferably at least 95% by weight, and most preferably at least 99% by weight of the total amount of dispersant when forming the solid electrolyte layer. In a particularly preferred embodiment of the process according to the invention, the drying conditions are adjusted so as to be within a range that ensures the complete removal of the dispersant when forming the solid electrolyte.

[0095] Process step d) In process step d) of the process according to the invention, at least some of the pores of the porous electrode body obtained in process step c) (i.e. the porous electrode body whose dielectric is at least partly covered with a solid electrolyte layer) are filled with an impregnation solution comprising at least one impregnation solvent.

[0096] Immersion in the impregnation solution or, correspondingly, impregnation with the impregnation solution is preferably carried out for a duration ranging from 1 second to 120 minutes, particularly preferably from 10 seconds to 60 minutes, most preferably from 30 seconds to 15 minutes. Immersion is preferably carried out by at least partially immersing the porous electrode body obtained in process step c) in the impregnation solution or by injecting the impregnation solution into the porous electrode body and thereby impregnating it with this impregnation solution. The introduction of the impregnation solution into the porous electrode body can be facilitated, for example, by increasing or decreasing pressure, vibration, ultrasound, or heat.

[0097] When the pores of the porous electrode body are impregnated with the impregnation solution in process step d), it is preferable to ensure that impregnation is achieved to the extent that at least 50% by volume, more preferably at least 75% by volume, and even more preferably at least 90% by volume of the open pore volume of the porous electrode body obtained in process step c) is filled with the impregnation solution, which preferably comprises at least one impregnation solvent in an amount of at least 50% by weight, preferably at least 75% by weight, even more preferably at least 90% by weight, and most preferably at least 95% by weight, in each case based on the total weight of the impregnation solution. In order to prevent further evaporation of the impregnation solvent from the pores in process step d), it is particularly preferable to achieve this filling amount just before carrying out process step e), i.e., before encapsulating the porous electrode body. Thus, the impregnation solution applied in process step d) remains at least to some extent, preferably completely, in the pores of the porous electrode body before encapsulation.

[0098] Preferred impregnation solvents used in the process according to the invention satisfy at least one of the following properties, and more preferably both of these properties: (β1) They have a boiling point (measured at 1013 hPa) of at least 200°C and less than 330°C; (β2) They have a melting point below 15°C, preferably below 5°C, even more preferably below -5°C.

[0099] In this context, it is particularly preferred that the at least one impregnation solvent is a compound containing two hydroxy groups or a compound containing one hydroxy group and one ether group, preferably one alkyl ether group; more preferably the at least one impregnation solvent is a mono-, di-, tri- or tetra-alkylene glycol, preferably diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol or tripropylene glycol, a mono-, di- or trialkylene glycol monoether, preferably diethylene glycol monomethyl ether, diethylene glycol monoethyl ether or diethylene glycol monobutyl ether, an alkanediol or an alkanediol monoether, Preferred alkanediols are 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,3-hexanediol, 2,4-hexanediol, 2,5-hexanediol, 3,4-hexanediol, 1,2-heptanediol, 1,3-heptanediol, 1,4-heptanediol, 1,5-heptanediol, 1,6- Heptanediol, 1,7-heptanediol, 2,3-heptanediol, 2,4-heptanediol, 2,5-heptanediol, 2,6-heptanediol, 3,4-heptanediol, 3,5-heptanediol, 1,2-octanediol, 1,3-octanediol, 1,4-octanediol, 1,5-octanediol, 1,6-octanediol, 1,7-octanediol, 1 The alkanediol is selected from the group consisting of 2,8-octanediol, 2,3-octanediol, 2,4-octanediol, 2,5-octanediol, 2,6-octanediol, 2,7-octanediol, 3,4-octanediol, 3,5-octanediol, 3,6-octanediol, 4,5-octanediol, and any further alkanediols having a molecular weight in the range of 70 to 180 g / mol. Also suitable as impregnation solvents are derivatives of the above alkanediols in which one hydrogen atom bonded to a carbon atom is replaced by an alkyl group, such as a methyl or ethyl group.

[0100] Particularly preferred are polyglycols having 2 to 4 repeating units. More preferably, the at least one impregnation solvent is selected from the group consisting of diethylene glycol, triethylene glycol, tetraethylene glycol and mixtures of at least two thereof, with diethylene glycol and triethylene glycol being most preferred.

[0101] In addition to the impregnation solvent, the impregnation solution may contain further components such as stabilizers (such as those mentioned above) and / or further solvents, in particular low-boiling solvents having a boiling point (determined at 1013 hPa) below 150° C., preferably below 120° C. However, it is preferred that the impregnation solution used in process step d) comprises at least one impregnation solvent in an amount of at least 50% by weight, preferably at least 75% by weight, and even more preferably at least 90% by weight, in each case based on the total weight of the impregnation solution. In the case of two or more impregnation solvents, these amounts refer to the total amount of impregnation solvent.

[0102] Encapsulation in process step e) In process step d), after at least some of the pores of the porous electrode body obtained in process step c) have been filled with the impregnation solution, the electrolytic capacitor can be completed, and in particular encapsulated, in a manner known to those skilled in the art. In this connection, it is preferred that less than 20% by weight, preferably less than 10% by weight, more preferably less than 1% by weight of the impregnation solution used in process step d) to fill some of the pores of the porous electrode body evaporates before encapsulating the porous electrode body, and it is even more preferred that essentially the entire amount, most preferably the entire amount, of the impregnation solution used in process step d) to fill some of the pores of the porous electrode body remains in the porous electrode body before it is encapsulated.

[0103] In the case of tantalum electrolytic capacitors, the capacitor body can be coated with a graphite layer and a silver layer, as is known, for example, from DE 102005043828(A), and in the case of aluminum wound capacitors, which correspond to the teachings of US Pat. No. 7,497,879(B2), the capacitor body is constructed in an aluminum cup, provided with a rubber seal and mechanically tightly closed by flanging.

[0104] The encapsulation is preferably achieved by sealing the capacitor body with a resin, such as an epoxy resin or a thermoplastic resin, such as those disclosed in EP 0 447 165 A2. In the case of aluminum electrolytic capacitors, the encapsulation is preferably achieved by providing the porous electrode body obtained in process step e) with an aluminum cup and closing it with a sealing rubber.

[0105] Heat treatment in process step f) In process step f), the encapsulated electrode body obtained in process step e) is heated at a temperature above 50°C, more preferably above 75°C, even more preferably above 100°C for more than 10 minutes, preferably more than 20 minutes, more preferably more than 30 minutes. In this connection, it is also preferred that the treatment temperature does not exceed 300°C and that the duration of the heat treatment does not exceed 24 hours, preferably not more than 3 hours, most preferably not more than 1 hour. Typically, the encapsulated capacitor is heated at a temperature in the range of 100-200°C for 10-60 minutes. [Brief explanation of the drawings]

[0106] The invention will now be described in more detail with reference to non-limiting figures and examples.

[0107] [Figure 1]1 shows a schematic cross-sectional view of a portion of a capacitor obtained by a process according to the invention. The capacitor comprises a porous electrode body 1, which includes pores 5 made primarily from a porous electrode material 2, such as aluminum. A dielectric 3 is formed as a thin layer on the surface of the electrode material 2, thereby forming a porous anode body comprising the electrode material 2 and the electrode body 1 made from the dielectric 3. A layer of solid electrolyte 4 (e.g., made from PEDOT / PSS particles) follows on the dielectric 3, optionally followed by further layers, thereby forming a capacitor body comprising the electrode material 2, the dielectric 3, and the electrode body 1 made from the solid electrolyte 4. The pores 5 of the porous electrode body 1 are at least partially filled with an impregnation solution (e.g., diethylene glycol, triethylene glycol, tetraethylene glycol, or a mixture of at least two thereof, see the gray shading in FIG. 1 ).

[0108] [Figure 2] 1 shows an aluminum capacitor according to the present invention, comprising a capacitor element 8 (porous electrode material 2 coated with dielectric 3 and solid electrolyte 4) and leads 10 contacting a porous anode foil and an opposing cathode foil, both foils rolled together with two sheets of separator paper between them and secured with end tape. The capacitor element 8 is held within an aluminum casing 7 in the shape of a closed-end cylinder, with a rubber seal 9 attached to the opening of the casing.

[0109] Measurement method: Solids To determine the solids content, 5 g of the liquid composition used in process step b) was dried at 100° C. for 15 hours and the solids content was determined by differential weighing.

[0110] pH value The pH value is determined using a pH meter. After calibration, the pH electrode is placed in the slowly stirred dispersion or solution until a constant pH reading is obtained.

[0111] conductivity A cleaned glass substrate was placed on a spin coater, and 10 ml of the liquid composition used in process step b) was dispensed onto the substrate. The excess solution was then shaken off by rotating the plate. The thus-coated substrate was then dried on a hot plate at 130 °C for 15 minutes. The layer thickness d was then determined using a layer thickness measuring device (Tencor, Alphastep 500). The electrical conductivity was measured by depositing Ag electrodes with a length L of 2.0 cm at a distance a of 1.0 cm through a shadow mask. The resulting structure of the Ag electrodes and the polymer film between them was electrically isolated from the surrounding polymer film on the substrate by scraping the polymer with a razor blade to form a rectangular frame. The surface resistance R of the polymer film was determined using an electrometer (Keithley 614) by contacting the Ag electrodes with gold contact pins.

[0112] The specific electrical resistivity ρ (unit: "Ωcm") is calculated using the following formula: ρ=R×L×d / a.

[0113] The conductivity σ (unit: S / cm) is calculated using the following formula: σ=1 / ρ

[0114] Measurement of particle size (d 50 ) The particle size is determined as disclosed by H.G. Muller in Colloid Polym. Sci. 267, 1113-1116 (1989). The diameter distribution d 50 The value is that 50% of the total weight of all particles of the conductive polymer in the dispersion is d 50 This indicates that the particle diameter can be assigned to particles having a diameter equal to or less than the value.

[0115] Equivalent series resistance (ESR) The equivalent series resistance (mΩ) was determined using an LCR meter (Agilent 4284A) at 20° C. and 100 kHz. For each capacitor experiment, two capacitors were fabricated and the average ESR value was determined.

[0116] Capacitance (CAP) The capacitance was determined using an LCR meter (Agilent 4284A) at 20° C. and 120 Hz. For each capacitor experiment, two capacitors were fabricated and the average capacitance value was determined.

[0117] Surge Test The capacitor was connected in series to a power bank via a 100 milliohm resistor and subjected to 18.4 V voltage pulses with a 30-second voltage-on (charging the capacitor) and 30-second voltage-off (discharging the capacitor) pulse period. The peak current of each charge and discharge was approximately 80 A. One surge cycle consisted of a charge and a discharge and lasted 60 seconds. For each capacitor experiment, two capacitors were prepared and the average capacitance value was determined. [Example]

[0118] Process step a) A porous electrode body for a cylindrical aluminum capacitor (shown in FIG. 2) with a rated voltage of 16 V was fabricated in the following manner.

[0119] The aluminum foil was etched to roughen its surface, and then anodized using an aqueous ammonium adipate solution to form a dielectric layer on the surface of the aluminum foil, thereby producing an anode foil.

[0120] The surface of the second aluminum foil was roughened by etching, thereby producing a cathode foil.

[0121] The anode and cathode leads were connected to the anode and cathode foils, respectively. The anode and cathode foils were rolled with two separator papers between them. Tape was applied to the outside of the rolled element to prevent the foil from unwinding. The rolled element was then subjected to another anodization to form a dielectric layer on the cut edge of the anode foil.

[0122] In this way, an anode body comprising an electrode body having a dielectric layer was prepared.

[0123] Process step b) The porous electrode body from process step a) was placed in a chamber containing a bath of a liquid composition comprising a conductive polymer. The air pressure in the chamber was reduced to 100 hPa. The anode body was immersed in the liquid composition for 300 seconds. The anode body was then removed from the liquid composition and the chamber was vented to atmospheric pressure.

[0124] Process step c) The anode body was dried at 120°C for 30 minutes and then at 150°C for 30 minutes.

[0125] The process steps b) and c) were carried out once again, thus obtaining a capacitor body.

[0126] Process step d) The capacitor body of process step c) was immersed in the impregnation solution for 300 seconds and then extracted from the impregnation solution.

[0127] Process step e) The capacitor body of process step d) was placed in a cylindrical aluminum housing and sealed with a rubber seal.

[0128] Process step f) The capacitor body of process step e) was heated at 135° C. for 1 hour.

[0129] Preparation Example 1 An aqueous solution of poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (Clevios P ​​VP AI 4083, Heraeus Germany) was concentrated to a solid content of 1.8% and homogenized 10 times under a pressure of 1500 bar using a high-pressure homogenizer. The pH of the solution was adjusted to 6 using ammonia. A liquid composition containing a conductive polymer was thus obtained. The electrical conductivity of the liquid composition was determined to be 0.001 S / cm. The particle distribution d 50 The value was 75 nm.

[0130] Preparation Example 2 An aqueous solution of poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (Clevios P ​​VP CH 8000, Heraeus Germany) was concentrated to a solids content of 1.8% and homogenized 10 times under a pressure of 1500 bar using a high-pressure homogenizer. 99 g of this polymer dispersion was mixed with 1 g of dimethyl sulfoxide. The pH of the solution was adjusted to 6 using ammonia. A liquid composition containing a conductive polymer was thus obtained. The electrical conductivity of the liquid composition was determined to be 0.05 S / cm. The particle distribution d 50 The value was 30 nm

[0131] Preparation Example 3 An aqueous solution of poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (Clevios PH, Heraeus Germany) was concentrated to a solid content of 1.8% and homogenized 10 times under a pressure of 1500 bar using a high-pressure homogenizer. The pH of the solution was adjusted to 6 using ammonia. A liquid composition containing a conductive polymer was thus obtained. The electrical conductivity of the liquid composition was determined to be 0.1 S / cm. The particle distribution d 50 The value was 45 nm.

[0132] Preparation Example 4 An aqueous solution of poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (Clevios PH 500, Heraeus Germany) was concentrated to a solid content of 1.8% and homogenized 10 times under a pressure of 1500 bar using a high-pressure homogenizer. The pH of the solution was adjusted to 6 using ammonia. A liquid composition containing a conductive polymer was thus obtained. The electrical conductivity of the liquid composition was determined to be 0.3 S / cm. The particle distribution d 50 The value was 26 nm.

[0133] Preparation Example 5 99.9 g of the liquid composition of Preparation Example 4 was mixed with 0.1 g of dimethyl sulfoxide. Thus, a liquid composition containing a conductive polymer was obtained. The conductivity of the liquid composition was determined to be 3 S / cm.

[0134] Preparation Example 6 99.7 g of the liquid composition of Preparation Example 4 was mixed with 0.3 g of dimethyl sulfoxide. Thus, a liquid composition containing a conductive polymer was obtained. The conductivity of the liquid composition was determined to be 9 S / cm.

[0135] Preparation Example 7 99.4 g of the liquid composition of Preparation Example 4 was mixed with 0.6 g of ethylene glycol. Thus, a liquid composition containing a conductive polymer was obtained. The conductivity of the liquid composition was determined to be 20 S / cm.

[0136] Preparation Example 8 97.5 g of the liquid composition of Preparation Example 4 was mixed with 2.5 g of dimethyl sulfoxide. Thus, a liquid composition containing a conductive polymer was obtained. The electrical conductivity of the liquid composition was determined to be 91 S / cm.

[0137] Preparation Example 9 95 g of the liquid composition of Preparation Example 4 was mixed with 5 g of ethylene glycol. Thus, a liquid composition containing a conductive polymer was obtained. The electrical conductivity of the liquid composition was determined to be 306 S / cm.

[0138] Preparation Example 10 90 g of the liquid composition of Preparation Example 4 was mixed with 10 g of 1,5-pentanediol. Thus, a liquid composition containing a conductive polymer was obtained. The electrical conductivity of the liquid composition was determined to be 346 S / cm.

[0139] Example 1 The capacitor was fabricated in the following manner.

[0140] A first anode body was prepared according to process step a). The anode body was then treated using the liquid composition containing the conductive polymer of Preparation Example 4 according to process steps b) and c). Process steps b) and c) were carried out again. Thus, a capacitor body was obtained.

[0141] The resulting capacitor body was then impregnated according to process step d) using ethylene glycol (EG) as the impregnation solution. The capacitor body was encapsulated according to process step e) and finally heat treated according to process step f) to obtain the finished capacitor. The ESR of the capacitor is shown in Table 1.

[0142] Example 2 Capacitors were fabricated and evaluated as in Example 1, except that diethylene glycol (DEG) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0143] Example 3 Capacitors were fabricated and evaluated as in Example 1, except that triethylene glycol (TEG) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0144] Example 4 Capacitors were fabricated and evaluated as in Example 1, except that tetraethylene glycol (TetraEG) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0145] Example 5 Capacitors were fabricated and evaluated as in Example 1, except that 1,2-propanediol was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0146] Example 6 Capacitors were fabricated and evaluated as in Example 1, except that 1,5-pentanediol was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0147] Comparative Example 1 Capacitors were fabricated and evaluated as in Example 1, except that dimethyl sulfoxide (DMSO) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0148] Comparative Example 2 Capacitors were fabricated and evaluated in the same manner as in Example 1, except that gamma-butyrolactone (GBL) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0149] Comparative Example 3 Capacitors were fabricated and evaluated as in Example 1, except that polyethylene glycol 400 (PEG400) was used as the impregnation solution in process step d). The ESR of the capacitors is shown in Table 1.

[0150] [Table 1]

[0151] Example 7 The capacitor was fabricated in the following manner.

[0152] A first anode body was prepared according to process step a). The anode body was then treated according to process steps b) and c) using the liquid composition containing the conductive polymer of Preparation Example 3. Process steps b) and c) were carried out again. Thus, a capacitor body was obtained.

[0153] The resulting capacitor body was then impregnated according to process step d) using diethylene glycol as the impregnation solution, encapsulated according to process step e) and finally heat treated according to process step f) to obtain the finished capacitor.

[0154] The capacitance of the capacitor was measured before and after a surge test of 1000 surge cycles at 20°C. The relative capacitance after the surge test was calculated according to the following formula: (Relative capacitance after surge test) = (Capacitance at 20°C after surge test) / (Capacitance at 20°C before surge test)

[0155] The relative capacitance after the surge test is shown in Table 2 in %.

[0156] Example 8 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 4. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0157] Example 9 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 5. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0158] Example 10 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 6. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0159] Example 11 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer used was that of Preparation Example 7. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0160] Example 12 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 8. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0161] Comparative Example 4 Capacitors were produced and evaluated in the same manner as in Example 7, except that the conductive polymer used was Preparation Example 1. The relative capacitances after the surge test are shown in Table 2 in %.

[0162] Comparative Example 5 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 2. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0163] Comparative Example 6 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer was prepared in Preparation Example 9. The relative capacitances after the surge test are shown in Table 2.

[0164] Comparative Example 7 Capacitors were manufactured and evaluated in the same manner as in Example 7, except that the conductive polymer used was Preparation Example 10. The relative capacitances after the surge test are shown in Table 2 as a percentage.

[0165] [Table 2]

[0166] Example 13 The capacitor was fabricated in the following manner.

[0167] A first anode body was prepared according to process step a). The anode body was then treated using the liquid composition containing the conductive polymer of Preparation Example 4 according to process steps b) and c). Process steps b) and c) were carried out again. Thus, a capacitor body was obtained.

[0168] The resulting capacitor body was then impregnated according to process step d) using diethylene glycol as the impregnation solution, encapsulated according to process step e) and finally heat treated according to process step f) to obtain the finished capacitor.

[0169] The capacitance of the capacitors was measured at 20° C. before and after 1500 hours of storage at a storage temperature of 125° C. The relative capacitance after 1500 hours of storage at 125° C. was calculated according to the following formula: (Relative capacitance after 1500 hours at 125°C) = (Capacitance at 20°C after 1500 hours storage at 125°C) / (Capacitance at 20°C before 1500 hours storage at 125°C)

[0170] The relative capacitance (%) after 1500 hours at 125°C is shown in Table 3.

[0171] Example 14 Capacitors were fabricated and evaluated in the same manner as in Example 13, except that the impregnation solution was a mixture of 99% by weight of diethylene glycol and 1% by weight of tannic acid. The relative capacitance (%) after 1500 hours at 125°C is shown in Table 3.

[0172] Comparative Example 8 A capacitor was manufactured and evaluated in the same manner as in Example 13, except that the capacitor body of process step d) was dried at 120° C. for 30 minutes and then at 150° C. for 30 minutes before process step e), and process step f) was omitted.

[0173] The relative capacitance (%) after 1500 hours at 125°C is shown in Table 3.

[0174] [Table 3] [Explanation of symbols]

[0175] 1 Porous electrode body 2 Electrode material 3 Dielectrics 4 Solid electrolyte 5 pores 6 Impregnation solution 7 Enclosure (aluminum housing) 8 Capacitor element (porous electrode material coated with dielectric and solid electrolyte and containing impregnating solvent) 9 Rubber seal 10 Lead Wire

Claims

1. 1. A process for manufacturing a capacitor, comprising the process steps: a) providing a porous electrode body (1) made of an electrode material (2), wherein a dielectric (3) at least partially covers the surface of said electrode material (2); b) introducing a liquid composition comprising a conductive polymer and a dispersant into at least a portion of the porous electrode body (1) provided in process step a), wherein the conductive layer made from the liquid composition has a conductivity of less than 100 S / cm, c) at least partially removing said dispersant from said porous electrode body (1) obtained in process step b) to form a solid electrolyte layer (4) at least partially covering the surface of said dielectric (3); d) filling at least some of the pores (5) of the porous electrode body (1) obtained in process step c) with an impregnation solution comprising at least one impregnation solvent, said at least one impregnation solvent having a boiling point of at least 150° C. (measured at 1013 hPa), e) encapsulating the porous electrode body (1) obtained in process step d), f) heating the encapsulated electrode body (1) obtained in process step e) at a temperature higher than 50°C for a period of more than 10 minutes.

2. 10. The process of claim 1, wherein the conductive layer made from the liquid composition used in process step b) has a conductivity of 0.1 S / cm or greater.

3. The conductive polymer in the liquid composition used in process step b) is present in the form of particles, the particles having a diameter d in the range of 1 to 100 nm. ５０ 3. The process of claim 1 or 2, comprising:

4. 4. The process according to claim 1, wherein the conductive polymer in the liquid composition used in process step b) is present in the form of a polythiophene / (poly)anion complex, wherein the polythiophene is poly(3,4-ethylenedioxythiophene) and the polyanion is the anion of polystyrenesulfonic acid.

5. 5. The process according to any one of claims 1 to 4, wherein the liquid composition applied in process step b) comprises less than 3 wt. % of a high-boiling solvent having a boiling point of at least 150°C (measured at 1013 hPa).

6. 6. The process according to any one of claims 1 to 5, wherein the at least one impregnation solvent in the impregnation solution applied in process step d) comprises at least one hydroxy group and has a molecular weight in the range of 70 to 195 g / mol.

7. 7. The process according to any one of claims 1 to 6, wherein the at least one impregnation solvent in the impregnation solution applied in process step d) has a melting point below 15°C.

8. 8. The process according to any one of claims 1 to 7, wherein the impregnation solvent in the impregnation solution applied in process step d) has a boiling point (measured at 1013 hPa) of at least 200°C and below 330°C.

9. 9. The process according to any one of claims 1 to 8, wherein the impregnation solution applied in process step d) has an ionic conductivity of less than 1000 μS / cm.

10. 10. The process according to any one of claims 1 to 9, wherein the at least one impregnation solvent in the impregnation solution applied in process step d) is a polyglycol having 2 to 4 repeat units.

11. 11. The process of claim 10, wherein the at least one impregnation solvent in the impregnation solution applied in process step d) is selected from the group consisting of diethylene glycol, triethylene glycol, tetraethylene glycol, and mixtures of at least two thereof.

12. The process according to any one of claims 1 to 11, wherein the impregnation solution used in process step d) comprises a stabilizer.

13. 13. The process of claim 12, wherein the stabilizer is gallic acid or gallic acid esterified with a sugar.

14. Use of a capacitor obtainable by the process according to any one of claims 1 to 13 in an electronic circuit.

15. An electronic circuit comprising a capacitor obtainable by a process according to any one of claims 1 to 13.

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