EP1673789A2

EP1673789A2 - Capacitor comprising a ceramic separating layer

Info

Publication number: EP1673789A2
Application number: EP04766545A
Authority: EP
Inventors: Gerhard HÖRPEL; Volker Hennige; Christian Hying; Sven Augustin
Original assignee: Degussa GmbH
Current assignee: Evonik Operations GmbH
Priority date: 2003-10-14
Filing date: 2004-08-19
Publication date: 2006-06-28
Also published as: US20070139860A1; JP5064800B2; JP2007508703A; CN1868012A; WO2005038833A3; DE10347568A1; WO2005038833A2; US7525788B2

Abstract

Disclosed is an electrochemical capacitor comprising a separating layer on a support. Said separating layer represents a porous inorganic, electrically non-conducting coating which is provided with particles of compounds of the elements Al, Si, and/or Zr, said particles being bonded to each other and to the support by means of an inorganic adhesive. The support can represent a porous electrode or a porous and planar substrate that is provided with polymer fibers.

Description

Capacitor with ceramic separation layer

The present invention relates to a capacitor which has a ceramic separation layer.

Conventional capacitors store electrical energy on two opposing capacitor plates separated by a dielectric. A distinction is made here:

1. Winding capacitors: In the case of winding capacitors, the metal coatings are firmly wound into a winding with the dielectric as a tape. The wrap is usually placed in a metal cup and sealed with a sealing compound to protect it against moisture.

2. Paper capacitors: They have two or more layers of cellulose paper as their dielectric. The coverings are made of aluminum foils. The connecting wires are welded to thin sheets that are also wrapped.

3. Plastic film capacitors: They have a dielectric made of plastic films such as polypropylene, polyester or polycarbonate. In the film-film capacitors, the metal coatings are aluminum foils. In the case of metallized plastic film capacitors (MK capacitors), the metal coatings are vacuum-deposited onto the plastic films. 4. Electrolytic capacitors: They have a thin oxide layer as a dielectric. This makes it possible to build small capacitors with large capacities.

5. Ceramic capacitors: They have a ceramic mass as a dielectric. Small ceramic capacitors are designed as tube and disc capacitors.

Electrochemical capacitors (ECs), also called supercapacitors or ultracapacitors, store energy in the electrical field of the electrochemical double layer. For extremely large capacity applications, porous electrodes with a very large surface area are used. Modern ECs cover the area between conventional capacitors (high power density, low energy density) and batteries or fuel cells (low power densities, high energy densities). A good overview of the prior art can be found in R. Kötz et al (Electrochimica Acta 45 (2000), 2483ff) and M. Mastragostino et al (Advances in Lithium-Ion Batteries, Kluwer Academic New York (2002), Pages 481 to 505). In principle, a distinction is made between several types of electrochemical capacitors: 1. Double-layer capacitors: "classic" variant in which the electrical energy is stored in an electrical double layer on the electrode surface. Typical electrode material here is graphite (natural, artificial, nanotubes, ...) with a lot large surfaces of up to 2,500 m ² / g.

2. Polymer capacitors: pseudocapacitor behavior due to p- or n-doping in polymers with conjugated π-electron systems.

3. Metal oxide capacitors: also pseudo-capacitor behavior due to fast, reversible Faraday protonation of the electrode surface. Typical electrode material here is RuO ₂ in an acidic electrolyte.

In electrochemical capacitors, a porous separator mechanically separates the electrodes from one another. Aqueous or non-aqueous solvents with a suitable conductive salt are used as the electrolyte. Polymer membranes are used as separators in aqueous systems; paper or a polyolefin, such as polyethylene (PE) or polypropylene (PP), is used in the area of non-aqueous systems. These separators have a low thermal stability, which is why simple welding is not possible when assembling the cells and, secondly, the separator melts or decomposes if the capacitor becomes too hot during operation, which leads to the destruction of the capacitor.

It was therefore an object of the present invention to provide a capacitor which has better thermal stability and which is simple to manufacture.

Surprisingly, it was found that the use of ceramic separation layers on supports as separators can improve the thermal stability of capacitors and that the production of such separation layers is easy. The separation layers can be applied both to electrodes as supports (separator electrode unit) or to supports having polymer fibers. Through these different types of production of the separation layer, the capacitor according to the invention can be added by adding little or no modifications according to the most of the usual manufacturing processes for capacitors.

Conventionally, a separator for electrochemical capacitors is a thin, porous, electrically insulating material with high ion permeability, good mechanical strength and long-term stability against those in the system, e.g. B. in the electrolyte of the electrochemical cell, chemicals and solvents used. It is intended to completely electronically isolate the cathode from the anode in electrochemical cells.

Separators currently used consist predominantly of porous organic polymer films or other organic or inorganic nonwovens, such as. B. Papers. These are made by different companies. Important producers are: Celgard, Tonen, Übe, Asahi, Binzer, Mitsubishi, Daramic and others.

Most separators are mechanically very unstable and easily lead to short circuits, so that a long service life cannot be achieved. A major disadvantage of organic polyolefin separators is their low thermal resistance of below 150 ° C. Even briefly reaching or exceeding the melting point of these polymers leads to a substantial melting of the separator and to the destruction of the capacitor. The use of such separators is therefore generally not safe, because when higher temperatures are reached, in particular above 150 ° C. or even 180 ° C., these separators and thus the capacitors are destroyed. In addition, polyolefin separators are extremely non-polar. However, since the electrolytes used are mostly very polar, there are great problems with wetting. This leads to extremely long filling times for the capacitors with the electrolyte and to a very limited selection of usable electrolytes.

In the field of battery separators, separators have recently been developed which have ceramic coatings on various substrates. For example, DE 198 38 800 Cl proposes an electrical separator with a composite structure, which comprises a flat, flexible substrate provided with a plurality of openings with a coating thereon. The material of the substrate is selected from metals and the coating is a continuous, porous, electrically non-conductive ceramic coating. The use of the ceramic coating promises thermal and chemical Resistance. However, the separators, which have a carrier or a substrate made of electrically conductive material (as stated in the example), have proven unsuitable for electrochemical cells, since the coating of the thickness described cannot be produced without defects over a large area. Short circuits are therefore very easy. In addition, metal meshes as thin as are required for very thin separators are not commercially available.

In DE 101 42 622 it could be shown that with a material which comprises a flat, flexible substrate provided with a plurality of openings with a coating located on and in this substrate, the material of the substrate being selected from woven or non-woven, non-electrically conductive fibers of glass or ceramic or a combination of such materials and the coating is a porous, electrically insulating, ceramic coating, and wherein the resulting battery separator has a thickness of less than 100 μm and is bendable, a battery separator can be produced , which has a sufficiently low resistance in connection with the electrolyte and nevertheless has a sufficiently large long-term resistance. In DE 102 08 277, the weight and thickness of the battery separator for lithium high-energy batteries was reduced by using a polymer fleece.

However, the fact that the separators described there are also suitable for use in capacitors, in particular in those which have no aqueous electrolytes, has not been recognized or described to date. The present invention therefore lies in the use of separators in capacitors which have a separation layer on a porous support, the separation layer being a porous inorganic, non-electrically conductive coating which is bonded to one another and to the support by particles of the elements A1 which are bonded to one another by an inorganic adhesive , Si and / or Zr.

The present invention therefore relates to a capacitor which has a separation layer, which is characterized in that the separation layer is present on a carrier, preferably a porous carrier, and is a porous inorganic, non-electrically conductive coating which is bonded to one another by an inorganic adhesive and particles of compounds of the elements AI, Si and / or Zr bonded to the carrier includes and its use as a storage for electrical energy, for example, for use in vehicles.

The separators according to the invention have the advantage that they are extremely wettable, in particular by organic polar solvents, and above all have good thermal stability. Due to the thermal stability, the assembly of the capacitors is easier on the one hand (welding), on the other hand, the separator does not melt or decompose if a cell should become too hot during operation. In particular, this makes a stack of capacitors, as is required to achieve higher voltages, significantly more fail-safe.

Due to the better wettability of the separators according to the invention, the electrochemical cell can be filled with electrolyte very quickly. This shortens the manufacturing time of the capacitors considerably. In addition, many other solvents can now be used that are difficult or impossible to use with polyolefin separators.

The construction of capacitors and the production of the same can e.g. the documents EP 1 202 299, US 6,585,152, EP 1 314 174 and EP 1 212 763 can be found. In particular, the construction and functioning of a capacitor can be the contribution of D.K. Haskeil, A.C. Kolb and W.G. McMillan in Encyclopedia of Applied Physics, Volume 6, pages 155 to 176, VCH Publishers New York, 1993 and the literature cited therein.

The capacitor according to the invention and a method for producing the separation layer present in it are described below, without the invention being restricted to these embodiments.

The capacitor according to the invention, which has a (ceramic) separation layer, is characterized in that the separation layer is present on a support, preferably a porous support, and is bonded to it, and is a porous inorganic, non-electrically conductive coating which is provided by an inorganic Adhesive particles and particles of compounds of the elements Al, Si and / or Zr bonded to one another and to the carrier, in particular oxide particles of these elements. The inorganic adhesive in the separation layer in the capacitor according to the invention is preferably selected from oxides of the elements Al, Si and / or Zr. The inorganic adhesive can have, for example, particles with an average particle size of less than 20 nm and have been produced via a particulate sol or have an inorganic network of the oxides which has been produced via a polymeric sol.

It may be advantageous if the separation layer additionally has an inorganic, silicon-containing network, the silicon of the network being bonded to the oxides of the inorganic coating via oxygen atoms and to the support having polymer fibers via an organic residue. Such a network is obtained if an adhesion promoter is used in the production of the separation layer and this adhesion promoter is subjected to the thermal treatment customary in the production.

Depending on the type of capacitor, the separation layer can have oxide particles of the elements Al, Si and / or Zr in different sizes. Capacitors according to the invention preferably have a separation layer which has particles with an average particle size of 0.5 to 10 μm, preferably 1 to 5 μm. Larger and smaller particle sizes are also conceivable, depending on the carrier used. The particles are particularly preferably bonded to an oxide of the metals Zr or Si. The ceramic material of the separation layer in the capacitor according to the invention formed by the particles and the inorganic adhesive preferably has an average pore size in the range from 50 nm to 5 μm and preferably from 80 nm to 800 nm.

The separation layer present in the capacitor according to the invention can be present on a wide variety of supports. In a preferred embodiment, the separation layer is present on a carrier which has fibers of polymers, glass and / or ceramics, polymer fibers being preferred. In this embodiment of the capacitor according to the invention, the separation layer can be present on or on and in the carrier mentioned and form a separator with it in the usual sense.

In this embodiment of the invention, the capacitors according to the invention preferably have carriers which are flexible and preferably have a thickness of less than 50 μm exhibit. The flexibility of the carrier ensures that the separator can also be flexible. Such flexible separators are essential, for example, in wound capacitors according to the invention.

The capacitor according to the invention preferably has a separator with a carrier which has a thickness of less than 30 μm, particularly preferably less than 20 μm. In order to be able to achieve a sufficiently high performance, it has proven to be advantageous for most applications if the separator according to the invention has a carrier which preferably has a porosity of greater than 50%, preferably 50 to 97%, particularly preferably 60 to 90% and very particularly preferably has from 70 to 90%. The porosity is defined as the volume of the carrier (100%) minus the volume of the fibers of the carrier, that is, the proportion of the volume of the carrier that is not filled by material. The volume of the carrier can be calculated from the dimensions of the carrier. The volume of the fibers results from the measured weight of the fleece under consideration and the density of the fibers, in particular the polymer fibers. In a further embodiment of the invention, the carrier is a fleece with a pore size of 5 to 500 μm, preferably 10 to 200 μm. It can also be advantageous if the carrier has a pore radius distribution in which at least 50% of the pores have a pore radius of 75 to 150 μm.

The porous (openwork) support preferably has woven or non-woven polymer or glass fibers. The carrier particularly preferably has a glass or polymer fabric or nonwoven or is such a fabric or nonwoven. As the polymer fibers, the carrier preferably has non-electrically conductive fibers of polymers, which are preferably selected from polyacrylonitrile (PAN), polyester, such as, for. B. polyethylene terephthalate (PET), polyamide (PA) and / or polyolefin (PO), such as. B. polypropylene (PP) or polyethylene (PE) or mixtures of such polyolefins. If the perforated support comprises polymer fibers, polymer fibers other than those mentioned above can also be used, provided that they both have the temperature stability required for the production of the capacitors or separators and are stable under the operating conditions. In a preferred embodiment, the carrier according to the invention has polymer fibers which have a softening temperature of greater than 100 ° C. and a melting temperature of greater than 110 ° C. exhibit. The carrier can comprise fibers and / or filaments with a diameter of 0.1 to 150 μm, preferably 1 to 20 μm, and / or threads with a diameter of 3 to 150 μm, preferably 10 to 70 μm. If the support has polymer fibers, these preferably have a diameter of 0.1 to 10 μm, particularly preferably 1 to 5 μm. Particularly preferred flexible nonwovens, in particular polymer nonwovens, have a basis weight of less than 20 g / m ² , preferably 5 to 15 g / m ² . In this way, a particularly low thickness and high flexibility of the carrier is guaranteed.

The capacitor according to the invention particularly preferably has a polymer fleece as a carrier, which has a thickness of less than 30 μm, preferably with a thickness of 10 to 20 μm. A particularly homogeneous pore radius distribution in the nonwoven is particularly important for use in a separator according to the invention. A homogeneous pore radius distribution in the nonwoven in conjunction with optimally coordinated oxide particles of a certain size leads to an optimized porosity of the separator according to the invention.

Depending on the intended use of the capacitor according to the invention and in particular depending on the electrolyte / conductive salt system used, it may be advantageous to use supports made of certain polymer fibers. Should the capacitors or the separation layer be impregnated with an organic solvent, e.g. a carbonate or acetonitrile, the capacitor preferably has supports which have fibers made of polyethylene terephthalates (PET) or polyamides (PA) or consist of these. If the capacitors according to the invention are impregnated with aqueous electrolyte systems, which often have strongly alkaline or strongly acidic electrolytes, it has proven to be advantageous if the supports have or consist of polymer fibers made of polyacrylonitrile.

The separators of separation layer and carrier present in the capacitor according to the invention in accordance with this embodiment can preferably be damaged down to any radius down to 100 m, preferably down to a radius of 100 m down to 50 mm and very particularly preferably from 50 mm down Bend 2 mm. These separators are also distinguished by the fact that they can have a tensile strength of at least 1 N / cm, preferably at least 3 N / cm and very particularly preferably greater than 6 N / cm. The high tensile strength and the good flexibility of the separator according to the invention has the The advantage of this separator is that it is easy to produce commercially standardized winding capacitors. In these cells, the electrode / separator layers are wound up in a spiral in standardized size and contacted.

The separation layer present in this embodiment of the capacitor preferably has a porosity of 30 to 70%. The porosity relates to the attainable, i.e. open, pores. The porosity can be determined using the known method of mercury porosimetry or can be calculated from the volume and density of the feedstocks used if it is assumed that there are only open pores. The separator present in the capacitor according to the invention can have a thickness in the range from 10 to 1000 μm, preferably 10 to 100 μm, very particularly preferably 10 to 50 μm. The separators preferably have a thickness of less than 50 μm, preferably less than 40 μm, particularly preferably a thickness of 5 to 30 μm and very particularly preferably a thickness of 15 to 25 μm. The thickness of the separator has a certain influence on the properties of the capacitor. Thin separators allow an increased packing density in a capacitor stack, so that a larger amount of energy can be stored in the same volume.

In a further preferred embodiment of the capacitor according to the invention, the latter has a porous electrode as a carrier and is suitable as an electrode in a capacitor and forms a so-called separator-electrode unit. In particular, electrodes are such

Suitable materials that can be used in double-layer capacitors or metal oxide capacitors. The separator-electrode unit comprises a porous one as an electrode in one

Capacitor suitable electrode and a separation layer applied to this electrode, which is characterized in that it comprises particles of the elements Al, Si and / or Zr bonded to one another and to the carrier by means of an inorganic adhesive.

The inorganic adhesive can e.g. be a fraction of metal oxide particles which differ in their average particle size, preferably by more than a factor of 10 and / or in the metal, from the particles of the elements Al, Si and / or Zr. In a preferred embodiment of the invention, the two particle fractions have metal oxide particles which differ both in the metal and in their particle size. The inorganic

Separation layer can contain small amounts of inorganic components organic, in particular organosilicon compounds. The proportion of these organic constituents in the inorganic separation layer is, however, preferably less than 5% by weight, particularly preferably less than 1% by weight and particularly preferably less than 0.1% by weight. These silanes serve as adhesion promoters in order to achieve a better connection of the ceramic to the electrodes.

The two particle fractions in the separation layer, regardless of whether they have oxides of the same or different metals as metal oxide, preferably have particles whose particle sizes differ by at least a factor of 10 and particularly preferably by at least a factor of 100. The separator-electrode unit according to the invention preferably has a separation layer which has metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode, which are separated by metal oxide particles which have a particle size ( Dk) smaller than the pores of the porous electrode, are glued. The thickness (z) of the separation layer is preferably less than 100 D _g and greater than or equal to 1.5 D _g and particularly preferably of less than 20 D _g and greater than or equal to 5 D _g .

The metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode are preferably Al ₂ O ₃ and / or ZrO ₂ particles. The metal oxide particles with an average particle size (D _k ) smaller than the average pore size (d) of the pores of the porous electrode are preferably SiO ₂ and / or ZrO ₂ particles.

The separator electrode units according to the invention particularly preferably have metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode and an average particle size (D _g ) of less than 10 μm, preferably less than 5 μm and very particularly preferably from less than 3 μm. With a thickness of the separation layer of 5 D _g, this results in a thickness of the separation layer of approximately max. For particles with an average particle size of 3 μm. 15 μm. Preferred layer thicknesses of the separation layer have thicknesses less than 25 μm, preferably from 10 to 15 μm. If necessary, the thickness of the separation layer can also be less than 10 μm. The application weights are preferably from 10 to 200 g / m, preferably smaller 100 g / m ² and very particularly preferably less than 50 g / m ² .

The separation layer of the separator-electrode unit of the capacitor according to the invention preferably has a porosity of 30 to 70% (determined by means of mercury porosimetry). Due to the high porosity and the good wettability of the separation layer, the separator-electrode unit or the capacitor can be easily impregnated or infested with electrolytes. In addition, thinner separator layers allow an increased packing density in a capacitor stack, so that a larger amount of energy can be stored in the same volume. The separator-electrode unit is therefore particularly suitable for capacitors with increased energy density.

The mechanical properties of the separator-electrode unit are essentially determined by the electrode due to the small thickness of the separation layer. Typical tensile strengths are in the range of the tensile strengths of the metallic carrier used for the production. In the case of expanded metals, depending on the expanded metal used, this is approx. 10 N / cm and higher and when using metal foils it is greater than 15 N / cm. The separator-electrode unit can be flexible. A separator-electrode unit according to the invention can preferably be down to a radius of down to 100 m, preferably to a radius of 100 m to down to 50 cm and particularly preferably to a radius of 50 cm down to 5, 4, 3, Bend 2 or 1 mm.

The separator-electrode unit according to the invention can have any conventional electrode that can be used in an electrochemical capacitor as a positive or negative electrode. The separator-electrode unit according to the invention preferably has an electrode as an electrode which is used in double-layer capacitors or metal oxide capacitors and which therefore has activated carbon with the largest possible surface area, such as activated carbon or RuO ₂ or IrO ₂ particles. Pastes are usually produced from these compounds in combination with graphite or carbon black, a temperature-stable polymer such as polyvinylidene fluoride, polyacrylic or polystyrene, and a solvent, which are applied to a thin metal foil (as a current collector), such as aluminum foil or copper foil, and through Removing the solvent can be solidified. Preferred electrodes have the highest possible porosity, preferably in the range from 20 to 40% (determined by mercury porosimetry) in order to provide the largest possible active surface. It is particularly important that not only a large specific surface area is important, but also that the pores have to have a certain minimum size so that they can be filled with electrolyte. Many small pores make a large contribution to the surface, but are ineffective for the capacitor. The minimum size of the active pores is about 5 nm. Particularly preferred electrodes have average pore sizes (d) from 5 nm to 20 μm, preferably from 10 nm to 1 μm. Multimodal pore distributions with many small pores but also a few large pores are preferred. The metal foil can be coated either simply or preferably on both sides. With both electrodes, in the case of current collectors coated on both sides, the separation layer can be applied on one or both sides, depending on how the capacitor is further constructed.

A double-sided coating of at least one electrode with a separation layer additionally simplifies the construction of a winding module, since one of the separation layers can serve as a separator, while the other layer represents the insulation layer that insulates the electrode from the counter electrode lying over it during winding.

In a particularly preferred embodiment, the capacitor according to the invention has a separation layer in which at least two fractions of oxides selected from Al ₂ O ₃

ZrO ₂ and / or SiO ₂ are present, the first ceramic fraction being obtained from a sol and the second fraction having particles with an average particle size of 200 nm to 5 μm, and the first fraction being present as a layer on the particles of the second fraction and the first fraction with a proportion of the coating of 1 to 30 parts by mass, the second fraction with a proportion of the coating of 5 to 94 parts by mass is present in the ceramic coating and a silicon network is also present, the silicon of the Network via oxygen atoms to the oxides of the ceramic coating, via organic residues to the polymer fleece and via at least one,

Chain containing carbon atoms is bonded to another silicon. The chain having carbon atoms preferably also has at least one

Nitrogen atom. The separation layer according to the invention preferably has a silicon network, in which the chains with which the silicon atoms are connected to one another are connected via carbon atoms, silicon atoms connected by nitrogen-containing chains was obtained by adding an amino group to a glycidyl group. As a result of these chains between the silicon atoms, in addition to an inorganic network which is formed via Si or metal-oxygen bridges, there is a second organic network which is crosslinked therewith and which significantly increases the stability of the membrane, in particular with respect to water.

In a further particularly preferred embodiment of the separation layer, it has at least three fractions of oxides selected from Al ₂ O ₃ , ZrO ₂ and / or SiO ₂ , the third fraction having particles with an average primary particle size of 10 nm to 199 nm and the first Fraction is present as a layer on the particles of the second and third fractions and the first fraction with a proportion of the coating from 1 to 30 parts by mass, the second fraction with a proportion of the coating from 30 to 94 parts by mass and the third fraction with a proportion is present in the coating of 5 to 50 parts by mass in the ceramic coating.

In this preferred embodiment, the large particles (second fraction) serve as filling material for the large meshes present in the carrier. The first ceramic fraction serves as an inorganic binder (inorganic adhesive), which fixes the particles to one another and to the carrier (or to the inorganic silicon network formed by the adhesion promoters). The inorganic network ensures particularly good adhesion of the ceramic coating to organic carriers, e.g. Polymer fleece sure. The particles of the third fraction, which have a medium particle size, are probably responsible for the particularly good flexibility.

In this embodiment, the capacitor according to the invention particularly preferably has a separation layer in which the third fraction has particles with an average primary particle size of 30 nm to 60 nm and the second fraction has particles with an average particle size of 1 to 4 μm and the first fraction also a portion of the coating of 10 to 20 parts by mass, the third fraction with a portion of the coating of 10 to 30 parts by mass and the second fraction with a portion of the coating of 40 to 70 parts by mass is present in the separation layer. It can be advantageous if the third particle fraction contains particles which have an average aggregate or agglomerate size of 1 to 25 μm. The third (particle) fraction preferably contains particles which have a BET surface area of 10 to 1000, preferably 40 to 100 m ² / g.

A particularly high flexibility of the separation layer according to the invention can be achieved if the particles of the third fraction are zirconium oxide or preferably silicon oxide particles and the particles of the second fraction are aluminum oxide particles and the ceramic fraction is formed from silicon oxide. The middle particles (third fraction, such as Sipemat, Aerosil or VP Zirkoniumoxid, all Degussa AG) and large particles (second fraction, such as the aluminum oxides CT800SG, AlCoA, and MZS, Martinswerke) are commercially available particles. The first ceramic fraction comes from brines, which are also commercially available or have to be produced by yourself.

Separation layers with a composition as mentioned above can, if the carrier allows it, be bent without damage down to any radius, preferably down to 50 m, preferably 10 cm and particularly preferably 5 mm, without this causing defects in the separation layer.

The separators according to the invention can of course also be used in all conventional capacitors

A further embodiment of a capacitor according to the invention, which can be, for example, a conventional capacitor, can have a separator-electrode unit which has a non-porous polymer film as the carrier, onto which a metal layer is vapor-deposited. The film can be, for example, a polyethylene terephthalate (PET) film. Aluminum, for example, is used as the metal. On this porous metal layer as a carrier, which together with the polymer film preferably has a thickness of 0.5 to 5 μm, preferably 1 to 2 μm, the ceramic coating described above is preferably present in a layer thickness of less than 10 μm, preferably less than 5 μm , The composition of the ceramic separation layer can correspond to that described above. Due to the presence of the separation layer the risk of the capacitor breaking through compared to capacitors without such a layer is significantly reduced.

In addition to the electrodes and the separation layer, which are usually housed in a housing and are provided with means for connecting the capacitor, the capacitor according to the invention has a dielectric, such as air in the case of some conventional capacitors, or an electrolyte, that is to say a system composed of solvent and Conductive salt, in the case of the electrochemical capacitor. In addition to known aqueous solvent / conductive salt systems, the capacitor according to the invention can in particular be a non-aqueous electrolyte selected from propylene carbonate (PC), N, N-dimethylformamide (DMF), γ-butyrolactone (GBL), N-methyl-2-pyrrolidone (NMP ) and acetonitrile (AN), and tetraalkylphosphonium or tetraalkylammonium salts, such as R ₄ NBF ₄ , RtNPF ₆ , R ₄ NClO or R ₄ NCF ₃ SO ₃ , with R = identical or different, substituted or unsubstituted alkyl, aryl, Alkyl-aryl, aryl-alkyl or cycloalkyl groups, the substituents being those selected from primary, secondary or tertiary alkyl groups, alicyclic groups, aromatic groups, -N-dialkyl, -NHAlkyl, -NH, fluorine, chlorine, bromine , Iodine, -CN, - OH -C (O) alkyl, -C (O) H or -C (O) O-alkyl, -CF ₃ , -O-alkyl, -C (O) N-alkyl and / or -OC (O) - alkyl may be present as conductive salts. As described above, depending on the electrolyte to be used, the separation layer or the support should be selected.

Like all capacitors, the capacitor according to the invention can be manufactured according to the prior art. The separation layer present in the capacitor according to the invention on and / or in a porous support or on the support is e.g. by applying a suspension to the support and solidifying it by heating at least once on and / or in the support, the suspension having a sol as an inorganic adhesive and at least one fraction of oxide particles selected from the oxides of the elements Al, Zr and / or Si, available.

Depending on whether the separation layer is to be applied to an electrode or on a carrier that is not suitable as an electrode, an appropriate carrier must be used.

As a carrier, which is not suitable as an electrode, those are preferably used, the one

Thickness of less than 30 μm, preferably less than 20 μm and particularly preferably a thickness of 10 up to 20 μm. Particularly preferred carriers are those as have already been described in the preceding description of the capacitor according to the invention. The porous support used therefore preferably has woven or non-woven polymer or glass fibers. A glass or polymer fabric or nonwoven is particularly preferably used as a support or such a fabric or nonwoven is used. The carrier used preferably has polymer fibers which have a softening temperature of greater than 100 ° C. and a melting temperature of greater than 110 ° C. It can be advantageous if the polymer fibers have a diameter of 0.1 to 10 μm, preferably 1 to 5 μm. In the method according to the invention, it is particularly preferred to use a carrier which has fibers selected from polyacrylonitrile, polyester, polyamide and / or polyolefin.

If an electrode is used as the carrier, any conventional electrode which is suitable as an electrode in a capacitor can be used. Such electrodes usually have a metal foil as a current collector for electrochemical capacitors, with a porous coating made of an electrically conductive material, such as RuO ₂ or IrO ₂ particles or activated carbon particles, coated with carbon black and graphite, and applied to one or both sides of the foil a binder are conductive to each other and connected to the current collector. For conventional capacitors, the electrodes have a metal layer on a polymer film.

The production of ceramic coatings, such as the separation layers present in the capacitors according to the invention, is known in principle from WO 99/15262.

The separation layers according to the invention are formed by applying a suspension, the inorganic electrically non-conductive particles to a, preferably porous, electrically conductive carrier (eg electrode) or a non-electrically conductive carrier (polymer fleece) and then solidifying the suspension to form an inorganic coating on and / or obtained in the porous support. The suspension can e.g. B. by Aufdmcken, pressing, pressing rolling, spreading, spreading, dipping, spraying or pouring onto the carrier. The suspension used to produce the coating has at least particles of Al ₂ O ₃ , ZrO ₂ and / or SiO ₂ and at least one sol, the elements Al, Zr and or Si, and is produced by suspending the particles in at least one of these sols , The suspension takes place by intensive mixing of the components. The particles used preferably have an average particle size of 0.5 to 10 μm, preferably an average particle size of 1 to 5 μm. Aluminum oxide particles, which preferably have an average particle size of 0.5 to 10 μm, preferably 1 to 5 μm, are particularly preferably used as metal oxide particles for producing the suspension. Aluminum oxide particles in the range of preferred particle sizes are offered, for example, by Martinswerke under the names MZS 3 and MZS 1 and by AlCoA under the names CT3000 SG, CL3000 SG, CT1200 SG, CT800SG and HVA SG.

It has been found that the use of commercially available oxide particles may lead to unsatisfactory results, since there is often a very wide particle size distribution. It is therefore preferred to use metal oxide particles, which by a conventional method such. B. wind classifying and hydroclassification were classified. Fractions in which the coarse particles, which make up up to 10% of the total amount, have been separated off by wet sieving are preferably used as oxide particles. This disruptive coarse fraction, which can also not be comminuted or can only be comminuted with great difficulty by the processes typical of the preparation of the suspension, such as milling (ball mill, attritor mill, mortar mill), dispersing (Ultra-Turrax, ultrasound), grinding or chopping. B. consist of aggregates, hard agglomerates, grinding ball abrasion. The aforementioned measures ensure that the inorganic porous layer has a very uniform pore size distribution. This is achieved in particular by using oxide particles which have a maximum particle size of preferably 1/3 to 1/5 and particularly preferably less than or equal to 1/10 of the thickness of the carrier (fleece) used.

The following Table 2 gives an overview of how the choice of different aluminum oxides affects the porosity and the resulting pore size of the respective porous inorganic separation layer. To determine this data, the Corresponding slip (suspensions or dispersions) is produced and dried and solidified as a pure molded body at 200 ° C.

Table 2: Typical data of ceramics depending on the type of powder used

The mean pore size and the porosity is to be understood as the mean pore size and the porosity that can be determined using the known mercury porosimetry method with a Porosimeter 4000 from Carlo Erba Instruments. Mercury porosimetry is based on the Washburn equation (EW Washburn, "Note on a Method of Determining the Distribution of Pore Sizes in a Porous Material", Proc. Natl. Acad. Sei., 7, 115-16 (1921) ).

The mass fraction of the suspended component (particles) is preferably 1 to 250 times, particularly preferably 1 to 50 times the sol used.

The sols are obtained by hydrolysing at least one (precursor) compound of the elements Zr, Al and / or Si. It may also be advantageous to add the compound to be hydrolyzed to alcohol or an acid or a combination of these liquids before the hydrolysis. The compound to be hydrolyzed is preferably hydrolyzed at least one nitrate, a chloride, a carbonate or an alcoholate compound of the elements Zr, Al and / or Si. The hydrolysis is preferably carried out in the presence of water, steam, ice, alcohol or an acid or a combination of these compounds. The sols are preferably obtained by hydrolyzing a compound of the elements Al, Zr or Si with water or an acid or obtained a combination of these compounds, the compounds being preferably dissolved in an anhydrous solvent and hydrolyzed with 0.1 to 100 times the molar ratio of water.

In one embodiment variant of the production process for the separation layer according to the invention, particulate sols are produced by hydrolysis of the compounds to be hydrolyzed. These particulate sols are characterized by the fact that the compounds formed in the sol by hydrolysis are present in particulate form. The particulate sols can be prepared as described above or as described in WO 99/15262. These brines usually have a very high water content, which is preferably greater than 50% by weight. It may be advantageous to add the compound to be hydrolyzed to alcohol or an acid or a combination of these liquids before the hydrolysis. The hydrolyzed compound can be peptized with at least one organic or inorganic acid, preferably with a 10 to 60% by weight organic or inorganic acid, particularly preferably with a mineral acid selected from sulfuric acid, hydrochloric acid, perchloric acid, phosphoric acid and nitric acid or a mixture of these acids are treated. The particulate sols produced in this way can then be used for the production of suspensions, the production of suspensions for application to polymer fiber nonwovens pretreated with polymeric sol being preferred.

In a further embodiment variant of the production process for a separation layer according to the invention, polymeric sols are produced by hydrolysis of the compounds to be hydrolyzed. These polymeric sols are distinguished by the fact that the compounds formed in the sol by hydrolysis are polymeric (ie chain-like crosslinked over a larger space). The polymeric sols usually have less than 50% by weight, preferably very much less than 20% by weight, of water and / or aqueous acid. In order to arrive at the preferred proportion of water and or aqueous acid, the hydrolysis is preferably carried out in such a way that the compound to be hydrolyzed with the 0.5 to 10 times molar ratio and preferably with half the molar ratio of water, steam or ice, based on the hydrolyzable G. ppe, the hydrolyzable compound, is hydrolyzed. Up to 10 times the amount of water can be used with very slow hydrolyzing compounds such as e.g. B. be used in tetraethoxysilane. Very fast hydrolyzing compounds Like zirconium tetraethylate, particulate sols can already form under these conditions, which is why 0.5 times the amount of water is preferably used for the hydrolysis of such compounds. Hydrolysis with less than the preferred amount of water, water vapor, or ice also gives good results. However, falling below the preferred amount of half a molar ratio by more than 50% is possible but not very useful, since if this value is not reached the hydrolysis is no longer complete and coatings based on such brine are not very stable.

To produce this brine with the desired very low proportion of water and / or acid in the sol, it may be advantageous if the compound to be hydrolyzed is in an organic solvent, in particular ethanol, isopropanol, butanol, amyl alcohol, hexane, cyclohexane, ethyl acetate and or mixtures of these compounds is dissolved before the actual hydrolysis is carried out. A sol produced in this way can be used to produce the suspension according to the invention or as an adhesion promoter in a pretreatment step. A suspension which has a polymeric sol of a compound of silicon is particularly preferably used for producing the separation layer according to the invention.

Both the particulate sols and the polymeric sols can be used as sols in the process according to the invention for producing the suspension. In addition to the

Soles that are available as just described can in principle also be commercially available brines, such as, for. B. zirconium nitrate sol or silica sol can be used. The process of making

Separation layers or separators by applying and solidifying a suspension to a carrier in and of itself are known from DE 101 42 622 and in a similar form from WO 99/15262, but not all parameters or starting materials can be used to prepare the in the invention Procedure used separator transferred. The process in WO

99/15262 is described, in this form is in particular not without compromise on polymers

Nonwoven materials are transferable, since the very water-containing sol systems described there often do not allow continuous wetting of the usually hydrophobic polymer fleece in depth, since the very water-containing sol systems do not or only poorly wet most polymer fleece. It was found that even the smallest non-wetted areas in the nonwoven material can result in membranes or separators being obtained that contain defects (such as Holes or cracks) and are therefore unusable.

It has been found that a sol system or a suspension which has been adapted to the polymers in terms of wetting behavior completely impregnates the carrier materials, in particular the nonwoven materials, and thus flawless coatings are obtainable. The wetting behavior of the sol or suspension is therefore preferably adjusted in the method according to the invention. This adaptation is preferably carried out by the production of polymeric sols or suspensions from polymeric sols, which sols one or more alcohols, such as. B. methanol, ethanol or propanol or mixtures which comprise one or more alcohols, and preferably aliphatic hydrocarbons. However, other solvent mixtures are also conceivable, which can be added to the sol or the suspension in order to adapt them to the nonwoven used (the carrier) in terms of crosslinking behavior.

To improve the adhesion of the inorganic components to polymer fibers or nonwovens as a carrier, it can be advantageous to add adhesion promoters, such as, for example, to the suspensions used. B. organofunctional silanes, such as. B. the Degussa silanes GLYMO, MEMO, AMEO, VTEO or Silfin. The addition of adhesion promoters is preferred for suspensions based on polymeric brine. In particular, compounds selected from the octylsilanes, the vinylsilanes, the amine-functionalized silanes and / or the glycidyl-functionalized silanes, such as, for. B. the Dynasilane from Degussa can be used. Particularly preferred adhesion promoters for polyethylene (PE) and polypropylene (PP) are vinyl, methyl and octylsilanes, the exclusive use of methylsilanes not being optimal, for polyamides and polyamines it is amine-functional silanes, for polyacrylates, polyacrylonitrile and polyesters it is glycidyl -functionalized silanes. For PVDF, for example, triethoxy (tridecafluorooctyl) silane is very suitable. Other adhesion promoters can also be used, but these have to be matched to the respective polymers. The adhesion promoters must be selected so that the solidification temperature is below the melting or softening point of the polymer used as the substrate and below its decomposition temperature. In particular, the silanes listed in Table 1 can be used as adhesion promoters. Suspensions according to the invention preferably have very much less than 25% by weight, preferably less than 10% by weight, of compounds which act as adhesion promoters can act. An optimal proportion of adhesion promoter results from the coating of the fibers and / or particles with a monomolecular layer of the adhesion promoter. The amount of adhesion promoter required in grams can be obtained by multiplying the amount of oxides or fibers used (in g) by the specific surface area of the materials (in m ² g ^" ') and then dividing by the specific space requirement of the adhesion promoter (in m ² g ^" ') are obtained, the specific space requirement often being in the order of 300 to 400 m ² g ^{" 1} .

Table 2 below contains an exemplary selection of adhesion promoters which can preferably be used, based on organo-functional Si compounds for typical polymers used as nonwoven material.

Table 2

With: AMEO - 3-aminopropyltriethoxysilane DAMO = 2-aminoethyl-3-aminopropyltrimethoxysilane GLYMO = 3-glycidyloxytrimethoxysilane MEMO = 3-methacryloxypropyltrimethoxysilane silfin = vinylsilane + initiator + catalyst VTEO = vinyltrimethoxysilane (vinyltrimethoxysilane) The suspension present on and / or in the carrier due to the application (the coating) can e.g. B. solidified by heating to 50 to 350 ° C. Since the maximum temperature is predetermined by the carrier material when using polymeric substrate materials, this must be adjusted accordingly so that the carrier material does not melt or soften. Depending on the embodiment of the method, the suspension present on and in the carrier is solidified by heating to 100 to 350 ° C. and very particularly preferably by heating to 200 to 280 ° C. It may be advantageous if the heating is carried out for 1 second to 60 minutes at a temperature of 150 to 350 ° C. The suspension is particularly preferably heated for solidification to a temperature of 110 to 300 ° C., very particularly preferably at a temperature of 170 to 280 ° C. and preferably for 0.5 to 10 min. The suspension is heated on a polymer nonwoven with polyester fibers preferably for 0.5 to 10 minutes at a temperature of 200 to 220 ° C. The heating of the suspension on a polymer fleece with fibers of polyamide is preferably carried out for 0.5 to 10 minutes at a temperature of 170 to 200 ° C. The composite can be heated by means of heated air, hot air, infrared radiation or by other heating methods according to the prior art.

The method for producing separation layers according to the invention can, for. B. be carried out so that the carrier is unrolled from a roll, at a speed of 1 m / h to 2 m / s, preferably at a speed of 0.5 m / min. up to 20 m / min and very particularly preferably at a speed of 1 m / min to 5 m / min by at least one apparatus which brings the suspension onto and into the carrier, such as, for. B. a roller, and at least one other apparatus which allows the solidification of the suspension on and in the carrier by heating, such as. B. passes through an electrically heated oven and the carrier thus provided with a separation layer is rolled up on a second roll. In this way it is possible to produce the separation layer in a continuous process. The pre-treatment steps can also be carried out in a continuous process while maintaining the parameters mentioned. In a further preferred embodiment of the method according to the invention for producing the separation layer, solidification is achieved by heating at least once a suspension on and in the carrier, in particular polymer fleece, the suspension being a sol and at least a fraction of oxide particles selected from the oxides of the elements Al, Zr, Ti and or Si, is characterized in that the suspension has a mixture of at least two different adhesion promoters, each based on an alkylalkoxysilane of the general formula I, before application

R _x -Si (OR) _4-x (1) with x = 1 or 2 and R = organic radical, where the radicals R may be the same or different, the adhesion promoters being chosen so that both adhesion promoters have alkyl radicals, each having at least one reactive group as a substituent, the reactive group on the alkyl radical of one coupling agent reacting with the reactive group of the other coupling agent during the at least one heating step to form a covalent bond, or one or more coupling agents according to formula I, the reactive group Have groups which react under the action of UV radiation to form a covalent bond, with the addition of an adhesion promoter which reacts under the action of UV radiation after application of the suspension to the polymer fleece (the carrier) at least one treatment with UV radiation occurs. The treatment with UV radiation can be carried out, for example, by means of a UV lamp, the amount of energy radiated in must be chosen so large that the adhesion promoters are crosslinked. Good results are achieved, for example, by treatment with a mercury vapor lamp for 0.1 to 24 hours, preferably 1 to 4 hours. The treatment with UV radiation can take place before or after the at least one heating. The UV treatment is preferably carried out after the suspension has been applied to the polymer fleece (the carrier) and before the suspension has been heated once.

The use of at least two of the said adhesion promoters presumably results in a network comprising silicon during the production of the separation layer, the silicon of the network via oxygen atoms to the oxides of the ceramic coating, via organic residues to the polymer fleece (the carrier) and via at least one, Chain containing carbon atoms is bonded to another silicon. Presumably the same effect is achieved by treatment with UV radiation at least once if a UV-active adhesion promoter is added to the suspension. As a result of the chains between the silicon atoms, there is an inorganic network, which is formed via Si or metal oxygen bridges, and a second organic network cross-linked with this, through which the stability the separation layer, especially against water, is significantly reinforced.

In principle, all adhesion promoters which satisfy the formula I mentioned above and in which at least two adhesion promoters each have an alkyl radical which is capable of building up a covalent bond in a chemical reaction with the alkyl radical of the other adhesion promoter can be used as adhesion promoters. In principle, all chemical reactions are possible, but the chemical reaction is preferably an addition or condensation reaction. The adhesion promoters can each have two or one alkyl radical (x in formula I is 1 or 2). The adhesion promoters used in the process according to the invention with a reactive group on the alkyl radical preferably have only one alkyl radical (x = 1). In the process according to the invention, at least two adhesion promoters can e.g. an adhesion promoter having an amino group on the alkyl radical and a glycidyl group on the alkyl radical are used. 3-Aminopropyltriethoxysilane (AMEO) and 3-glycidyloxytrimethoxysilane (GLYMO) are particularly preferably used as adhesion promoters in the process according to the invention. The molar ratio of the two adhesion promoters to one another is preferably from 100 to 1 to 1 to 100, preferably from 2 to 1 to 1 to 2 and very particularly preferably approximately 1 to 1. As a UV-active adhesion promoter, under the action of UV radiation a covalent bond between the adhesion promoter molecules is preferred

Methacryloxypropyltrimethoxysilane (MEMO) used. The adhesion promoters are e.g. available from Degussa AG.

In order to obtain a sufficiently stable network, the suspension according to the invention preferably has a proportion of 0.1 to 20% by mass, preferably 2 to 10% by mass, of adhesion promoters. In addition to the “reactive” adhesion promoters mentioned, the suspension can also have other adhesion promoters selected from the organofunctional silanes mentioned above. These adhesion promoters can also have a proportion of 0.1 to 20% by mass, preferably 2 to 10% by mass, in the suspension -% present.

In a further preferred embodiment variant of the method according to the invention, a suspension is used which has a sol and at least two fractions of oxide particles selected from the oxides of the elements Al, Zr, Ti and / or Si and at least a first fraction of primary particles with an average particle size of 200 nm to 5 microns and a share of the suspension of 30 to 94 parts by mass and at least a second fraction an average Has primary particle size of 10 nm to 199 nm and a proportion of the suspension of 5 to 50 parts by mass. In addition, the suspension can again have adhesion promoters, in particular also the reactive adhesion promoters mentioned above. The particles of the first fraction are preferably aluminum oxide particles and are offered, for example, by Martinswerke under the names MZS 3 and MZS1 and by AlCoA under the names CT3000 SG, CL3000 SG, CT1200 SG, CT800SG and HVA SG. Degussa AG offers, for example, aluminum oxide, silicon oxide or zirconium oxide particles of the second fraction under the names Sipemat, Aerosil, Aerosil P25 or Zirkoniumoxid VP.

Suspensions are particularly preferably used in which the mass fraction of the suspended component (second and third particle fraction) is 1.5 to 250 times, particularly preferably 5 to 20 times the first fraction from the sol used.

If an electrode is coated as a carrier with the method according to the invention, it has proven to be advantageous if the separation layer is not present in the electrode as a carrier. To ensure this, it has proven to be advantageous if the suspension used preferably has metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode. Al ₂ O ₃ and / or ZrO ₂ particles are preferably used as metal oxide particles or as metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode. The particles used as metal oxide particles particularly preferably have an average particle size of less than 10 μm, preferably less than 5 μm and very particularly preferably less than 3 μm.

If a suspension is to be used which has particles which are smaller than the average pore size of the pores of the electrode, it may be necessary to adjust the viscosity of the suspension. By setting a correspondingly high viscosity of the suspension in the absence of external shear forces, penetration of the suspension into the pores of the electrode used as a carrier is prevented (starch viscosity, non-Newtonian behavior). Such behavior can be achieved by adding auxiliary substances that influence the flow behavior. Auxiliaries are also used to adjust the viscosity of the suspension preferably used inorganic materials. Pyrogenic silicas, such as, for example, Aerosile from Degussa AG, such as, for example, Aerosil 200, are particularly preferably added to the suspension to adjust the viscosity of the suspension. Since these substances are very effective as auxiliaries for adjusting the viscosity, it is sufficient if the mass fraction of silica in the suspension is from 0.1 to 10% by weight, preferably from 0.5 to 5% by weight.

Depending on the carrier material used, the carrier with separation layer produced in this way can be combined as a separator or as a separator-electrode unit with the other components required for a capacitor in accordance with the prior art to form a capacitor. If the capacitor produced in this way is an electrochemical capacitor, the separation layer between the electrodes must still be filled with the electrolyte system before the housing of the capacitor can be closed.

The capacitors according to the invention produced in this way can be used as storage for electrical energy in vehicles, electric vehicles, in starter modules for engines, in particular diesel units, uninterruptible power supplies and in any technical device in which very large electrical outputs are required over only short periods of time.

The present invention is described by the following examples, without the scope of protection which arises from the claims and the description being restricted by the examples.

Examples: Example 1: Separator S450P according to the invention

30 g of a 5% strength by weight aqueous HNO ₃ solution, 10 g of tetraethoxysilane, 2.5 g of methyltriethoxysilane and 7.5 g of Dynasilane GLYMO were first added to 130 g of water and 15 g of ethanol. 125 g of the aluminum oxides Martoxid MZS-1 and Martoxid MZS-3 were then suspended in this sol, which was initially stirred for a few hours. This slip was homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there was no loss of solvent. A 20 cm wide PET fleece with a thickness of approx. 20 μm and a weight per unit area of approx. 15 g / m2 was then coated with the above slip in a continuous rolling process (belt speed approx. 30 m / h, T = 200 ° C.). In this rolling process, the slip is rolled onto the fleece using a roller that moves in the opposite direction to the belt direction (direction of movement of the fleece). The fleece then runs through a 1 m long oven which has the specified temperature. The same method or arrangement for coating is used in the following experiments. A separator with an average pore size of approximately 450 nm and a thickness of 35 μm was obtained at the end.

Example 2: Capacitor according to the invention

A copper foil with a width of 165 mm and a width of 160 mm is obtained with a dispersion of 10 g of highly activated coal (1200 m Ig, according to the BET method as described in Winnacker-Küchler (3.) 7, 93f. Z. Anal. Chem. 238, 187-193 (1968)) and 1 g PVDF in 89 g NMP continuously coated using the rolling method known from Example 1 (belt speed approx. 30 m / h, T = 150 ° C.). This material is subsequently used as an electrode.

The separator according to Example 1 is first cut to a width of approximately 165 mm and then processed together with two electrodes to form a winding with approximately 150 windings (pairs of electrodes, each with 2 separator layers). This coil is put into an aluminum housing (50 mm diameter, height 172 mm), electrically connected to the external power connections and filled with the electrolyte (concentrated solution of tetraethylammonium borofluoride in acetonitrile).

The capacitor will have a weight of approx. 400 g, a capacity of approx. 1850 farads at a voltage of 2.5 V. The maximum current is 450A. Example 3: Separator-electrode unit according to the invention

A copper foil with a width of 165 mm is continuously rolled over a width of 160 mm with a dispersion of 10 g of highly activated carbon (1200 m ² / g, determined according to the BET method) and 1 g of PVDF in 89 g of NMP using that known from Example 1 Roll-on process (belt speed approx. 30 m / h, T = 150 ° C) coated. The coating takes place in parallel on both sides. 30 g of a 5% strength by weight aqueous HNO ₃ solution, 10 g of Dynasilan GLYMO and 10 g of Dynasilan GLYMO were first added to 130 g of water and 15 g of ethanol. 200 g of the aluminum oxide CT1200SG were then suspended in this sol, which was initially stirred for a few hours. This slip was homogenized for at least a further 24 h using a magnetic stirrer, the stirring vessel having to be covered so that there was no loss of solvent.

In a second step, this electrode is coated with this slip only on one side over a width of 162 mm using the known rolling method (belt speed approx. 60 m / h, T = 180 ° C.).

Example 4: Capacitor According to the Invention

Two separator-electrode units, consisting of an electrode equipped with a separator layer according to Example 3 on one side, are processed into a coil, whereby care must be taken that a ceramic separator layer in each case cleanly separates the electrodes from one another. This coil is placed in an aluminum housing (60 mm diameter, height 172 mm), electrically connected to the external power connections and filled with the electrolyte (concentrated solution of tetraethylammonium borofluoride in acetonitrile).

The capacitor will have a weight of approx. 525 g, a capacity of approx. 2700 farads at a voltage of 2.5 V. The maximum current is 600A.

Claims

claims

1. capacitor, which has a separation layer, characterized in that the separation layer is present on a carrier and is bonded to it and is a porous inorganic, non-electrically conductive coating, the particles of compounds bonded to one another and to the carrier by an inorganic adhesive which comprises elements AI, Si and / or Zr.

2. A capacitor according to claim 1, characterized in that the carrier comprises woven or non-woven polymer or glass fibers.

3. A capacitor according to claim 2, characterized in that the carrier is flexible and has a thickness of less than 50 microns.

4. A capacitor according to claim 2 or 3, that the polymer fibers are selected from fibers of polyacrylonitrile, polyamide, polyester and / or polyolefin.

5. A capacitor according to claim 1, characterized in that the carrier is an electrode suitable as an electrode in a capacitor.

6. A capacitor according to claim 5, characterized in that the carrier is a porous electrode suitable as an electrode in a capacitor.

7. A capacitor according to claim 5 or 6, characterized in that the separation layer metal oxide particles with an average particle size (D _g ) has larger than the average pore size (d) of the pores of the electrode, which are bonded by metal oxide particles which have a particle size (D _k ) smaller than the pores of the porous electrode.

8. A capacitor according to at least one of claims 5 to 7, characterized in that the separation layer has a thickness (z) of less than 100 D _g and greater than or equal to 1.5 D _g .

9. A capacitor according to claim 8, characterized in that the separation layer has a thickness (z) of less than 20 D _g and greater than or equal to 5 D _g .

10. A capacitor according to at least one of claims 7 to 9, characterized in that the metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous positive electrode Al ₂ O ₃ - and / or ZrO ₂ particles are.

11. A capacitor according to at least one of claims 7 to 9, characterized in that the metal oxide particles with an average particle size (D _k ) smaller than the average pore size (d) of the pores of the porous positive electrode SiO ₂ - and / or ZrO ₂ -Particles are.

12. A capacitor according to at least one of claims 7 to 11, characterized in that the metal oxide particles with an average particle size (D _g ) larger than the average pore size (d) of the pores of the porous electrode have an average particle size (D _g ) of smaller Have 10 μm.

13. A capacitor according to at least one of claims 1 to 12, characterized in that the separation layer has a porosity of 30 to 70%.

14. A capacitor according to at least one of claims 1 to 13, characterized in that the inorganic adhesives are selected from oxides of the elements AI, Si and / or Zr.

15. A capacitor according to at least one of claims 1 to 14, characterized in that the inorganic adhesive has particles with an average particle size of less than 20 nm and was produced via a particulate sol or has an inorganic network of the oxides which is produced via a polymeric sol has been.

16. Capacitor according to at least one of claims 1 to 15, characterized in that an inorganic, silicon-containing network is additionally present, the silicon of the network via oxygen atoms to the oxides of the inorganic coating and via an organic residue to the support, the polymer fibers has, is bound.

17. A capacitor according to at least one of claims 1 to 16, characterized in that the bonded particles of the compounds of the elements Al, Si and or Zr present in the separator had an average particle size of 0.5 to 10 μm.

18. A capacitor according to at least one of claims 1 to 17, characterized in that it has a non-aqueous electrolyte selected from propylene carbonate, N, N-dimethylformamide, γ-butyrolactone or acetonitrile as a solvent, and tetraalkylphosphonium or tetraalkylammonium salts as conductive salts.

19. A capacitor according to at least one of claims 1 to 18, characterized in that the separation layer by applying a suspension to the support and solidifying it by heating at least once on and in the support, the suspension being a sol as an inorganic adhesive and at least one fraction of oxide particles selected from the oxides of the elements Al, Zr and / or Si, is available.

20. A capacitor according to claim 19, characterized in that the heating of the suspension on the carrier is carried out for 0.5 to 10 minutes at a temperature of 170 to 280 ° C.

21. Use of a capacitor according to at least one of claims 1 to 20 as a storage for electrical energy in vehicles.