DE102018202929A1 - Hybrid supercapacitor and method of making a hybrid supercapacitor - Google Patents

Abstract

The invention relates to a hybrid supercapacitor (1) comprising at least one positive electrode (22), at least one negative electrode (21), at least one separator (18) and an electrolyte (15), wherein the electrolyte (15) is a solvent selected from the group consisting of acetonitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene methyl carbonate, ethylmethyl carbonate, propionitrile, glutaronitrile, adiponitrile and mixtures thereof, and a polymer and optionally a conductive salt.
Furthermore, the invention relates to a method for producing a supercapacitor and the use of a supercapacitor and the use of a mixture comprising a solvent and a polymer

Description

The invention relates to a hybrid supercapacitor comprising at least one positive electrode, at least one negative electrode, at least one separator and an electrolyte. Furthermore, the invention relates to a method for producing a supercapacitor and the use of a supercapacitor and the use of a mixture comprising a solvent and a polymer.

State of the art

The storage of electrical energy by means of electrochemical energy storage systems such as electrochemical capacitors (supercapacitors) or electrochemical primary or secondary batteries has been known for many years. The energy storage systems mentioned differ in the underlying principle of energy storage.

Supercapacitors typically include a negative and a positive electrode, which are separated by a separator. There is also an electrolyte between the electrodes which is ionically conductive. The storage of electrical energy is based on the fact that, when a voltage is applied to the electrodes of the supercapacitor, an electrochemical double layer is formed on the surfaces thereof. This bilayer is formed of charge carriers from the electrolyte, which are arranged on the surfaces of the oppositely electrically charged electrodes. A redox reaction is not involved in this type of energy storage. Therefore, supercapacitors can theoretically be charged as often as desired and thus have a very long service life. Also, the power density of the supercapacitors is high, whereas the energy density is rather low compared to, for example, lithium-ion batteries.

The energy storage in primary and secondary batteries, however, takes place by a redox reaction. These batteries also usually comprise a negative and a positive electrode, which are separated by a separator. There is also a conductive electrolyte between the electrodes. In lithium-ion batteries, one of the most common secondary battery types, energy storage occurs through the incorporation of lithium ions into the electrode active materials. During operation of the battery cell, ie during a discharge process, electrons flow in an external circuit from the negative electrode to the positive electrode. Within the battery cell, lithium ions migrate from the negative electrode to the positive electrode during a discharge process. In this case, the lithium ions from the active material of the negative electrode store reversible, which is also referred to as delithiation. During a charging process of the battery cell, the lithium ions migrate from the positive electrode to the negative electrode. The lithium ions reversibly reenter the active material of the negative electrode, which is also referred to as lithiation.

Lithium-ion batteries are characterized by the fact that they have a high energy density, which means that they can store a large amount of energy per mass or volume. In return, however, they have only a limited power density and life. This is disadvantageous for many applications, so that lithium-ion batteries in this area can not or only to a limited extent can be used.

Hybrid supercapacitors are a combination of these technologies and are likely to close the gap in the applications of lithium-ion battery technology and supercapacitor technology.

Hybridsuperkondensatoren usually also have two electrodes, each comprising a current collector, separated by a separator. The transport of electric charge between the electrodes is ensured by electrolytes. The electrodes generally comprise as active material a conventional supercapacitor material, hereinafter also referred to as static capacitive active material, as well as a material which is capable of undergoing a redox reaction with the charge carriers of the electrolyte and forming an intercalation compound thereof, hereinafter also electrochemical redox -Active material called. The energy storage principle of the hybrid supercapacitors is thus based on the formation of an electrochemical double layer in combination with the formation of a faradic lithium intercalation compound. The energy storage system thus obtained has a high energy density at the same time high power density and long life.

Hybrid supercapacitors also include other components such as separators, current collectors and a housing. The current collectors serve to electrically contact the electrode material and connect them to the terminals of the capacitor. They must have good conductivity. To prevent corrosion, current collectors and housings are usually made of the same material, mostly aluminum.

The energy density and power density of a hybrid supercapacitor is determined by the electrode active materials used. The used electrochemical redox active material allows a high energy density, whereas the static capacitive active material determines the power density.

Negative electrodes comprising active materials consisting of lithium titanium oxides, in particular Li ₄ Ti ₅ O ₁₂ (LTO) are known from the prior art for use in lithium-ion batteries. Cericola et al., Journal of Power Sources 2011, 196, pages 10305-10313 U.S. Patent Nos. 5,430,488, 5,329,688, 4,360,488, 5,329,431 and 5,200,400 describe a hybrid supercapacitor having an electrode composition containing 80% by weight of active material, 5% by weight of graphite and 5% by weight of carbon black as conductive additives and 10% by weight of a polymeric binder (PTFE). The positive electrode active material contains 28% by weight of LiMn ₂ O ₄ (LMO) and 72% by weight of activated carbon. The negative electrode active material contains 19% by weight of Li ₄ Ti ₅ O ₁₂ (LTO) and 81% by weight of activated carbon.

Hybrid supercapacitor electrodes are often made by a solvent-based process using N-methyl-2-pyrrolidone.

The electrolyte in the hybrid supercapacitor is usually liquid. The electrolyte used in hybrid supercapacitors is generally acetonitrile, from which, upon intense heating and in case of fire, toxic gases such as hydrogen cyanide and nitrogen oxides are formed which form explosive mixtures with air. This also applies to other solvents.

US 2011/0195314 A1 describes a process for the preparation of gel polymer electrolyte secondary batteries. The secondary battery includes a cathode, an anode, a separator, and a gel polymer electrolyte in a battery case. A surface of the cathode, anode, separator or battery case is coated with a polymerization initiator, and a gel polymer electrolyte is formed by filling a gel polymer electrolyte composition comprising an electrolyte solvent, an electrolyte salt, and a polymer electrolyte monomer into the battery case and polymerizing the monomer.

US 2009/0030102 A1 discloses a process for forming a crosslinked polymer gel used in batteries or solar cells.

Disclosure of the invention

There is proposed a hybrid supercapacitor comprising at least one positive electrode, at least one negative electrode, at least one separator and an electrolyte, wherein the electrolyte is a solvent selected from the group consisting of acetonitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate , Ethylene methyl carbonate, ethyl methyl carbonate, propionitrile, glutaronitrile, adiponitrile and mixtures thereof, a polymer and optionally a conductive salt. Acetonitrile is particularly preferred as a solvent.

The electrolyte preferably comprises the conductive salt, which is in particular selected from the group consisting of lithium chlorate (LiClO ₄ ), lithium tetrafluoroborate (LiBF ₄ ), lithium hexafluorophosphate (LiPF ₆ ), lithium hexafluoroarsenate (LiAsF ₆ ), lithium trifluoromethanesulfonate (LiSO ₃ CF ₃ ), lithium bis ( trifluoromethylsulphonyl) imide (LiN (SO ₂ CF ₃ ) ₂ ), lithium bis (pentafluoroethylsulphonyl) imide (LiN (SO ₂ C ₂ F ₅ ) ₂ ), lithium bis (oxalato) borate (LiBOB, LiB (C ₂ O ₄ ) ₂ ), Lithium difluoro (oxalato) borate (LiBF ₂ (C ₂ O ₄ )), lithium tris (pentafluoroethyl) trifluorophosphate (LiPF ₃ (C ₂ F ₅ ) ₃ ) and mixtures thereof.

1. a. Bereitstellen mindestens einer positiven Elektrode, mindestens einer negativen Elektrode, mindestens eines Separators und eines Gehäuses,
2. b. Bereitstellen eines Lösungsmittels, eines Polymers und gegebenenfalls eines Leitsalzes,
3. c. Mischen des Lösungsmittels, des Polymers und gegebenenfalls des Leitsalzes, so dass ein Elektrolyt entsteht, wobei der Elektrolyt eine höhere Viskosität aufweist als das bereitgestellte Lösungsmittel,
4. d. Anordnen der mindestens einen positiven Elektrode, der mindestens einen negativen Elektrode und des mindestens einen Separators in dem Gehäuse und Einfüllen des Elektrolyten oder des Lösungsmittels, des Polymers und gegebenenfalls des Leitsalzes in das Gehäuse.

In addition, a method for producing a hybrid supercapacitor is proposed, comprising the following steps:

1. a. Providing at least one positive electrode, at least one negative electrode, at least one separator and a housing,
2. b. Providing a solvent, a polymer and optionally a conducting salt,
3. c. Mixing the solvent, the polymer and optionally the conducting salt to form an electrolyte, wherein the electrolyte has a higher viscosity than the solvent provided,
4. d. Arranging the at least one positive electrode, the at least one negative electrode and the at least one separator in the housing and charging the electrolyte or the solvent, the polymer and optionally the conducting salt into the housing.

By the polymer as thickener, the solvent is thickened, so that a gel is formed and the electrolyte has a higher viscosity than the solvent used.

The solvent is mixed with the polymer and preferably no further polymerization takes place in the mixture, but the formation of the macromolecules of the polymer is already completed before contact with the solvent.

By the electrolyte in the form of a gel, which is formed by the presence of the polymer in the solvent, the escape of the solvent from the hybrid supercapacitor and the formation of toxic gases when heated and be avoided or prevented in case of fire.

Preferably, the polymer is selected from the group consisting of polyethylene oxide (PEO), copolymers of polyethylene oxide such as polystyrene-polyethylene oxide (PEO-PS), polysulfones (PSU), polyacrylic acid (PAA), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), carboxymethylcellulose ( CMC), polymalonic acid esters, polyacrylonitrile (PAN), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), and mixtures thereof. Particularly preferred are polyethylene oxide, polyethylene block copolymers and polymalonic acid esters, especially Polymalonsäureester.

Polyethylene oxide, which is also referred to as polyethylene glycol, is a polymer which is composed of the repeating unit (-CH ₂ -CH ₂ -O-) and preferably comprises 10 to 1000, in particular 20 to 500 repeating units per molecule. Copolymers of polyethylene oxide include in particular block copolymers of at least one polyethylene oxide block and at least one block of an ionically or radically polymerizable monomer, in particular styrene or a styrene derivative (eg α-methylstyrene). A particularly preferred copolymer is a polyethylene oxide [b] polystyrene block copolymer.

• mit R¹, R²= H oder F;
• R³ = organischer Rest, insbesondere Alkylrest der Formel -(CH₂)_m-(CH₃), wobei m eine ganze Zahl von 1 bis 10, vorzugsweise 2 bis 8, darstellt; und
• n = 2 bis 1000, insbesondere 10 bis 500.

Polymalonic acid esters include repeat units of the general formula (I):

• with R ¹ , R ² = H or F;
• R ³ = organic radical, in particular alkyl radical of the formula - (CH ₂ ) _m - (CH ₃ ), where m is an integer from 1 to 10, preferably 2 to 8; and
• n = 2 to 1000, in particular 10 to 500.

The solvent is preferably more than 50 wt .-% of acetonitrile.

The electrolyte preferably contains 5% by weight to 30% by weight of polymer and 70% by weight to 95% by weight of acetonitrile. Preferably, the electrolyte contains the conductive salt having a concentration in a range of 0.1 mol / L to 3 mol / L.

Advantageously, the electrolyte has a dynamic viscosity in a range of 0.3 mPa · s to 400 mPa · s, the viscosity, for example, after DIN 53019-1: 2008-09 can be determined. By adding the polymer, the electrolyte has a higher viscosity than the solvent without polymer.

The separator may contain cellulose, polyolefins, polyesters and / or fluorinated polymers. Furthermore, the separator may contain ceramic materials, which in particular contain MgO and / or Al ₂ O ₃ , or consist of the ceramic materials. The separator may be single-layered or multi-layered.

Preferably, the separator consists of a polymer selected from the group consisting of polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylonitrile, polymethylmethacrylate, polyvinylidene fluoride, polymalonic acid esters and mixtures thereof.

• - 72,5 bis 96,5 Gew.-% eines Aktivmaterials,
• - 2,5 bis 7,5 Gew.-% mindestens eines Leitadditivs, und
• - 1 bis 20 Gew.-% mindestens eines Bindemittels,

wobei das Aktivmaterial der positiven Elektrode insbesondere eine Zusammensetzung ist, bestehend aus

1. a) 0 bis 80 Gew.-% eines Redoxaktivmaterials
2. b) 20 bis 100 Gew.-% Aktivkohle.

The positive electrode preferably comprises an active material composition having the following components:

• 72.5 to 96.5% by weight of an active material,
• 2.5 to 7.5% by weight of at least one conductive additive, and
• From 1 to 20% by weight of at least one binder,

wherein the positive electrode active material is, in particular, a composition consisting of

1. a) 0 to 80 wt .-% of a redox active material
2. b) 20 to 100 wt .-% activated carbon.

Suitable electrochemical redox active materials for the positive electrode are, for example, lithiated intercalation compounds which are capable of reversibly taking up and releasing lithium ions. The positive redox active material may comprise a composite oxide containing at least one metal selected from the group consisting of cobalt, magnesium, nickel, and lithium.

One embodiment of the present invention comprises a positive electrode redox active material comprising a compound of the formula LiMO ₂ wherein M is selected from Co, Ni, Mn, Cr or mixtures of these and mixtures of these with Al. In particular, LiCoO ₂ and LiNiO ₂ are mentioned.

In a preferred embodiment, the redox active material is a Material comprising nickel, ie LiNi ₁ - _x M _'x O _2, wherein M' is selected from Co, Mn, Cr and Al, and 0 ≤ x <. 1 Examples include lithium nickel cobalt aluminum oxide cathodes (eg, LiNi _0.8 Co _0.15 Al _0.05 O ₂ ; NCA) and lithium nickel manganese cobalt oxide cathodes (eg, LiNi _0.8 Mn _0.1 Co _0.1 O ₂ ; NMC (811) or LiNi _0.33 Mn _0.33 Co _0.33 O ₂ ; NMC (111)).

Further, as preferred positive redox active materials, mention may be made of overlaid layered oxides. Examples are Li _{1 + x} Mn _2-y M _y O ₄ where x ≤ 0.8, y <2; Li _{1 + ×} Co _{1 -y} M _y O ₂ where x ≤ 0.8, y <1; Li _{1 + ×} Ni _{1 -yz} Co _y M _z O ₄ where x ≤ 0.8, y <1, z <1 and y + z <1. In the aforementioned compounds, M may be selected from Al, Mg and / or Mn.

In particular, two or more of the positive redox active materials may also be used in combination with each other. A preferred embodiment comprises, for example, compounds of the formula n (Li ₂ MnO ₃ ): n-1 (LiNi ₁ -x M ' _x O ₂ ) where M' is selected from Co, Mn, Cr and Al and 0 <n <1 and 0 <x <1.

Furthermore, in particular spinel compounds (eg LiMn ₂ O ₄ ), olivine compounds (eg LiFePO ₄ ), silicate compounds (eg Li ₂ FeSiO ₄ ), tavorite compounds (eg LiVP04F), Li ₂ MnO ₃ , Li _1.17 Ni _0.17 Co _0.1 Mn _0.56 O ₂ and Highlight Li ₃ V ₂ (PO ₄ ) ₃ as suitable positive active materials.

• - 50 bis 94 Gew.-% eines Aktivmaterials,
• - 5 bis 30 Gew.-% mindestens eines Leitadditivs, und
• - 1 bis 20 Gew.-% mindestens eines Bindemittels,

wobei das Aktivmaterial der positiven Elektrode insbesondere eine Zusammensetzung ist, bestehend aus

1. a) 90 bis 100 Gew.-% Li₄Ti₅O₁₂ (LTO), TiO₂, H₂Ti₃O₇, H₂Ti₆O₁₃, H₂Ti₁₂O₂₅ oder Gemischen daraus und
2. b) 0 bis 10 Gew.-% Aktivkohle.

The negative electrode preferably comprises an active material composition having the following components:

• From 50 to 94% by weight of an active material,
• 5 to 30% by weight of at least one conductive additive, and
• From 1 to 20% by weight of at least one binder,

wherein the positive electrode active material is, in particular, a composition consisting of

1. a) 90 to 100 wt .-% Li ₄ Ti ₅ O ₁₂ (LTO), TiO ₂ , H ₂ Ti ₃ O ₇ , H ₂ Ti ₆ O ₁₃ , H ₂ Ti ₁₂ O ₂₅ or mixtures thereof and
2. b) 0 to 10 wt .-% activated carbon.

As guide additives, for example, graphite or carbon black may be used alone or in combination with each other.

As the binder, for example, polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose and / or polymalonic acid esters can be used.

Preferably, the solvent and the polymer and optionally the conductive salt are mixed prior to filling in the housing. Most preferably, the polymerization of the polymer is completed prior to mixing with the solvent.

In an alternative embodiment, the solvent and the polymer may be mixed during filling or after filling in the housing. Here, first the solvent can be initially charged and then the polymer can be added or the polymer can already be introduced into the housing, in which case the solvent is added.

Preferably, the at least one positive electrode, the at least one negative electrode and / or the at least one separator are produced solvent-free, which can also be referred to as dry production. Particularly preferably, the at least one positive electrode and / or the at least one negative electrode are produced by means of extrusion.

1. A) Herstellen einer ersten Elektroden-Folie umfassend
   1. i. einen ersten Extrusionsschritt, wobei mindestens vier Komponenten einem ersten Extruder jeweils separat zugeführt werden, die mindestens vier Komponenten in dem ersten Extruder gemischt werden, dem ersten Extruder ein erstes Extrudat entnommen wird und dem ersten Extruder weniger als 1 Gew.-% Herstellungslösungsmittel, bezogen auf das erste Extrudat, zugeführt wird, und
   2. ii. einen ersten Pressschritt, wobei eine erste Schichtdicke des ersten Extrudats verringert wird und die erste Elektroden-Folie gebildet wird,
2. B) Bereitstellen einer Ionen-leitenden und elektrisch isolierenden Separator-Folie,
3. C) Bereitstellen einer zweiten Elektroden-Folie und
4. D) Verbinden der ersten Elektroden-Folie, der Separator-Folie und der zweiten Elektroden-Folie zu der Elektrodenanordnung.

The hybrid supercapacitor preferably comprises an electrode arrangement comprising the at least one positive electrode, the at least one negative electrode and the separator, wherein the electrode arrangement is produced more preferably by a method comprising the following steps:

1. A) producing a first electrode film comprising
   1. i. a first extrusion step, wherein at least four components are separately fed to a first extruder, at least four components are mixed in the first extruder, a first extrudate is taken from the first extruder, and less than 1% by weight of the first extruder is based on manufacturing solvent the first extrudate is fed, and
   2. ii. a first pressing step, wherein a first layer thickness of the first extrudate is reduced and the first electrode foil is formed,
2. B) providing an ion-conducting and electrically insulating separator film,
3. C) providing a second electrode foil and
4. D) connecting the first electrode foil, the separator foil and the second electrode foil to the electrode arrangement.

The first electrode foil is preferably a cathode foil, in particular a freestanding cathode foil, and the second electrode foil is preferably an anode foil, in particular one freestanding anode foil. The first electrode foil preferably contains lithium. Furthermore, the second electrode foil advantageously contains lithium and / or a silicon composite, and the second electrode foil preferably consists of lithium.

For separate feeding of the at least four components, the first extruder preferably has at least four separate feed openings, which are preferably arranged one behind the other in the conveying direction. The first extruder is preferably a screw extruder, which may have one or more screws, wherein the screws can rotate in the same direction or in opposite directions.

The first extruder is preferably supplied with less than 0.5% by weight of manufacturing solvent, based on the first extrudate, and more preferably the first extrusion step is carried out without solvent. As a manufacturing solvent, organic solvents such as cyclohexanone, N-methyl-2-pyrrolidone (NMP) and acetonitrile and mixtures thereof are understood. The first extruder is preferably also fed with less than 1% by weight of water, based on the first extrudate, and more preferably the first extrusion step is carried out without water. Particularly preferably, the first extrusion step is carried out dry.

• iii. einen zweiten Extrusionsschritt, wobei mindestens zwei Komponenten in einem zweiten Extruder gemischt werden, dem zweiten Extruder ein zweites Extrudat entnommen wird und dem zweiten Extruder bevorzugt weniger als 1 Gew.-% Herstellungsösungsmittel, bezogen auf das zweite Extrudat, zugeführt wird und
• iv. einen zweiten Pressschritt, wobei eine zweite Schichtdicke des zweiten Extrudats verringert wird und die Separator-Folie gebildet wird.

The provision of the ion-conducting and electrically insulating separator film in step b) preferably comprises the following steps:

• iii. a second extrusion step, wherein at least two components are mixed in a second extruder, a second extrudate is taken from the second extruder, and preferably less than 1% by weight of manufacturing solvent, based on the second extrudate, is fed to the second extruder;
• iv. a second pressing step, wherein a second layer thickness of the second extrudate is reduced and the separator film is formed.

The at least two components are preferably fed separately to the second extruder. For separate feeding of the at least two components, the second extruder preferably has at least two separate feed openings, which are preferably arranged one behind the other in the conveying direction. The second extruder is preferably a screw extruder, which may have one or more screws, wherein the screws can rotate in the same direction or in opposite directions. The second extruder may be identical to the first extruder, with optionally only two of the at least four separate feed openings of the first extruder being used.

The second extruder is preferably less than 0.5 wt .-% of manufacturing solvent based on the second extrudate fed, more preferably, the second extrusion step is performed solvent-free. Preferably, less than 1% by weight of water, based on the second extrudate, is also fed to the second extruder, and more preferably the second extrusion step is carried out anhydrous. Particularly preferably, the second extrusion step is carried out dry.

The second extrusion step is preferably carried out at a temperature which is above the melting temperature of at least one of the at least two components, in particular at a temperature of more than 100 ° C., more preferably at a temperature of more than 120 ° C. and particularly preferably at a temperature of more than 130 ° C. Usually, the temperature during the second extrusion step is not more than 200 ° C, preferably not more than 180 ° C, and more preferably not more than 160 ° C.

The first pressing step and / or the second pressing step, wherein the first extrudate or the second extrudate is pressed, is advantageously carried out in a calendering device. A calender device is understood to mean a machine which has at least two rolls, which can preferably be tempered, which are arranged in parallel and which run in opposite directions. Between two rollers is a gap whose width is adjustable. The first extrudate or the second extrudate is applied to the rolls and pressed as a web through the gap, wherein the first layer thickness of the first extrudate and optionally the second layer thickness of the second extrudate are reduced. The resulting web represents the first electrode foil or the separator foil.

An inventive hybrid supercapacitor finds advantageous use in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product. Consumer electronics products are in particular mobile phones, tablet PCs and notebooks.

The invention is further directed to the use of a mixture comprising a solvent, preferably acetonitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene methyl carbonate, ethylmethyl carbonate, propionitrile, glutaronitrile, adiponitrile or mixtures thereof, in particular acetonitrile, and A polymer selected from the group consisting of polyethylene oxide, copolymers of polyethylene oxide, such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, Carboxymethyl cellulose, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, and polymalonic acid esters, and optionally a conductive salt, as an electrolyte in a hybrid supercapacitor.

Advantages of the invention

Due to the thickened electrolyte in the event of a leakage of the hybrid supercapacitor, the hybrid supercapacitor according to the invention or the method according to the invention protects the user of the hybrid supercapacitor from exposure to toxic gases and from possible fire. In particular, acetonitrile is harmful to health by inhalation, ingestion and skin contact. Acetonitrile is also absorbed through the skin and acts as a blood poison in the body, so avoiding contact with this solvent is beneficial.

Accordingly, the security risk is reduced in case of leakage and increased safety for the user. At the same time, the functionality is maintained with increased safety and a better high-temperature behavior is achieved.

list of figures

• 1 zeigt den schematischen Aufbau eines Hybridsuperkondensators.

An embodiment of the invention will be explained in more detail with reference to the drawing and the following description:

• 1 shows the schematic structure of a hybrid supercapacitor.

In 1 is the construction of a hybrid supercapacitor 1 shown schematically. A flat current collector 31 contacts a negative electrode 21 and connects them to the negative terminal 11 , Opposite is a positive electrode 22 , which is also conductive with a current collector 32 for derivation to the positive terminal 12 is bound. The two electrodes 21 . 22 be through a separator 18 separated and are in a housing 2 arranged. The electrolyte 15 provides an ionic conductive connection between the two electrodes 21 . 22 and contains a polymer.

example

To prepare a positive electrode, a mixture of 33 . 34 Parts by weight of LMO and 61.9 parts by weight of activated carbon as active material (weight ratio LMO / activated carbon: 35/65) and 4.76 parts by weight of carbon black as conductive additive. This is dry blended for 10 minutes at 1000 rpm in a blender. Then, 105 parts by weight of a 4.76 wt .-% binder solution (PVDF in DMSO) was added and the resulting suspension was first stirred for 2 min at 900 U / min, then treated for 5 min with ultrasound and then again for 4 min at Stirred at 2500 rpm. The suspension is poured by means of a doctor blade method directly onto a current conductor with a thickness of about 100 microns to the positive electrode and dried.

To prepare a negative electrode, a binder solution consisting of 4% by weight CMC in water is first prepared. 20 parts by weight of this binder solution are mixed in a mixing unit with the 10 parts by weight conductive additive for 1 minute at 800 rpm and then for 1 minute at 1500 rpm. Then another 20 parts by weight of water are added and mixed for a further 5 min at 1500 rev / min and 2 min at 2500 rev / min. 20.5 parts by weight of this mixture are then mixed with 15 parts by weight LMO and 26 parts by weight of a 1 wt .-% CMC mixture with the addition of 4 parts by weight of ethanol for 4 min at 1500 rev / min and 2 min at 2500 rev / min, then this 5 min treated with ultrasound and then stirred again for 4 min at 2500 rev / min. By further addition of ethanol / water, a desired viscosity is set and the pourable suspension is then applied by means of a doctor blade method directly onto a current collector (aluminum foil) and dried. The generated layer thickness is about 50μm when dry.

The weight ratio of the negative electrode active material composition to the positive electrode is 0.5.

A separator is made on the basis of cellulose. An electrolyte contains LiClO ₄ , acetonitrile and a polymer.

The invention is not limited to the embodiments described herein and the aspects highlighted therein. Rather, within the scope given by the claims a variety of modifications are possible, which are within the scope of expert action.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2011/0195314 A1 [0013]
• US 2009/0030102 A1 [0014]

Cited non-patent literature

• Cericola et al., Journal of Power Sources 2011, 196, pages 10305-10313 [0010]
• DIN 53019-1: 2008-09 [0026]

Claims (15)

A hybrid supercapacitor (1) comprising at least one positive electrode (22), at least one negative electrode (21), at least one separator (18) and an electrolyte (15), the electrolyte (15) being a solvent selected from the group consisting of Acetonitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene methyl carbonate, ethyl methyl carbonate, propionitrile, glutaronitrile, adiponitrile and mixtures thereof, and a polymer and optionally a conducting salt. Hybrid supercapacitor (1) after Claim 1 characterized in that the polymer is selected from the group consisting of polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, polymalonic acid esters and mixtures thereof. Hybrid supercapacitor (1) after Claim 1 or 2 , characterized in that the electrolyte (15) consists of more than 5 wt .-% of the polymer. Hybrid supercapacitor (1) according to one of Claims 1 to 3 , characterized in that the electrolyte (15) contains 5 wt .-% to 30 wt .-% polymer and 70 wt .-% to 95 wt .-% acetonitrile. Hybrid supercapacitor (1) according to one of Claims 1 to 4 , characterized in that the electrolyte (15) has a dynamic viscosity in a range of 0.3 mPa · s to 400 mPa · s. Hybrid supercapacitor (1) according to one of Claims 1 to 5 characterized in that the separator (18) comprises polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, and / or polymalonic acid esters. Hybrid supercapacitor (1) according to one of Claims 1 to 6 , characterized in that the at least one positive electrode (22) contains LiMn ₂ O ₄ (LMO) and / or the at least one negative electrode (21) contains Li ₄ Ti ₅ O ₁₂ (LTO). Use of a hybrid supercapacitor (1) according to one of Claims 1 to 7 in an electric vehicle (EV), in a hybrid vehicle (HEV), in a plug-in hybrid vehicle (PHEV) or in a consumer electronics product. Process for the preparation of a hybrid supercapacitor (1) comprising the following steps: a. Providing at least one positive electrode (22), at least one negative electrode (21), at least one separator (18) and a housing (2), b. Providing a solvent and a polymer and optionally a conducting salt, the polymer preferably selected from the group consisting of polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinylpyrrolidone, carboxymethylcellulose, polyacrylonitrile, polymethylmethacrylate, polyvinylidene fluoride and polymalonic acid esters, c. Mixing the solvent and the polymer and optionally the conducting salt to form an electrolyte (15), wherein the electrolyte (15) has a higher viscosity than the solvent provided, d. Arranging the at least one positive electrode (22), the at least one negative electrode (21) and the at least one separator (18) in the housing (2) and filling the electrolyte (15) or the solvent and the polymer into the housing (2 ). Method according to Claim 9 , characterized in that the solvent and the polymer are mixed prior to filling in the housing (2). Method according to Claim 9 , characterized in that the solvent and the polymer are mixed during or after filling in the housing (2). Method according to one of Claims 9 to 11 , characterized in that the at least one positive electrode (22), the at least one negative electrode (21) and / or the at least one separator (18) are produced solvent-free. Method according to one of Claims 9 to 12 , characterized in that the at least one positive electrode (22) and / or the at least one negative electrode (21) are produced by extrusion. Method according to one of Claims 9 to 13 , characterized in that the solvent consists of more than 50 wt .-% of acetonitrile. Use of a mixture comprising a solvent, preferably acetonitrile, 3-methoxypropionitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethylene methyl carbonate, ethylmethyl carbonate, propionitrile, glutaronitrile, adiponitrile or mixtures thereof, and a polymer selected from the group consisting of A group consisting of polyethylene oxide, copolymers of polyethylene oxide such as polystyrene-polyethylene oxide, polysulfones, polyacrylic acid, polyvinyl alcohol, polyvinyl pyrrolidone, carboxymethyl cellulose, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride, and polymalonic acid esters, and optionally a conductive salt, as electrolyte (15) in a hybrid super capacitor (1).

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