DE102014001025A1 - Electrochemical cell - Google Patents

Abstract

An electrochemical cell comprising at least one negative electrode, wherein the negative electrode comprises at least one material which is designed as an electrochemical active material, and at least one positive electrode, wherein the positive electrode comprises at least one material which is designed as an electrochemical active material, and at least one separator which spaces the at least one positive electrode from the at least one negative electrode, in particular electrical, and at least one envelope, in particular designed as a foil envelope, which at least partially, preferably at least one, negative electrode and the at least one positive electrode and the at least one separator completely encloses, wherein the electrochemical cell further comprises at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, wherein the at least one sheath this e, at least one Lithiumdendritenabbau device also encloses, and wherein preferably the at least one Lithiumdendritenabbau device comprises at least one material which is designed to reduce lithium dendrites, in particular to reduce.

Description

The present invention relates to an electrochemical cell wherein the electrochemical cell has at least one negative electrode, at least one positive electrode, at least one separator and at least one sheath, wherein the electrochemical cell further comprises at least one lithium dendrite degradation device. The cell may preferably be used for driving a vehicle with electric motor, preferably with hybrid drive or in "plug-in" operation.

Electrochemical cells, especially lithium secondary batteries, find because of their high energy density and high capacity as energy storage in mobile information devices such. As in mobile phones, in tools or in electrically powered cars and in automobiles with hybrid drive application. Despite these very different fields of application of electrochemical cells, all the cells used, but especially those for the propulsion of automobiles, have to fulfill high requirements: the highest possible electrical capacity and energy density, which remains stable over a large number of charging and discharging cycles, with the lowest possible weight.

Especially the lifetime but also the safety of electrochemical cells is often dependent on the aging of the electrodes. In the aging process, the electrochemical cells lose capacity and performance. This process takes place to a greater or lesser extent in most common electrochemical cells, and is u. a. depending on the conditions of use (temperature, storage conditions, state of charge, etc.), but also the quality and processing of the materials during the manufacturing process of the electrochemical cell. Thus, a high-quality processing of pure materials can lead to long-lasting and also safe electrochemical cells, which age only a little over a longer period of time, thus losing little capacity and power.

However, such measures are often not sufficient to obtain a long-lived and especially safe electrochemical cell, since chemical reactions occur inside the cell during the operation of a cell, which are partly irreversible, and which not only lead to capacity loss of the electrochemical cell but can also pose a not insignificant security risk.

Thus, in particular lithium dendrites, which can arise during charging and discharging processes, are known as causers of so-called "hot spots" and micro-short circuits. When producing electrochemical cells which work with lithium ion-based active material, it is therefore important to ensure that as far as possible no lithium dendrites are formed or can form during the operation of the electrochemical cell.

In particular, cells in which lithium dendrites have arisen despite protective measures represent a not insignificant safety problem. Such cells are also more sensitive to pressure and temperature stresses. Cells in which lithium dendrites have formed can experience an irreversible loss of capacity, even as far as a short circuit, which can destroy the cell.

In the US 5,961,672 For example, it is described that a lithium metal anode is coated with a polymer film to prevent lithium dendrite formation during operation of the electrochemical cell.

As already mentioned, lithium dendrites can be formed not only during the regular operation of an electrochemical cell, but also during initial, conditioning charging and discharging operations.

In particular, when "enclosing" electrode assemblies of electrochemical cells in a film pouch, folds may be formed on the surfaces of the film envelope in which foamy or dendritic lithium intercalates during the first charge and discharge cycles. This can then no longer participate in the energy-supplying deposits and removals into or out of the electrochemical active material of the electrodes. As a result, the capacity of the electrochemical cell - as already mentioned - adversely affects, in particular lowers, the safety of the cell.

An object of the present invention is therefore to provide an electrochemical cell which is particularly durable and safe.

This is achieved according to the invention by the teaching of the independent claims. Preferred developments of the invention are the subject of the dependent claims.

To achieve this object, as described in detail below, an electrochemical cell is provided, comprising: at least one negative electrode, wherein the negative electrode comprises at least one material, which is designed as an electrochemical active material, and at least one positive electrode, wherein the positive electrode at least comprising a material which acts as an electrochemical active material is configured, and at least one separator, the at least one positive electrode spaced from the at least one negative electrode, in particular electrically isolated, and at least one envelope, in particular configured as a film envelope, which the at least one negative electrode and the at least one positive electrode and the at least one separator at least partially, preferably completely enclosing the electrochemical cell further comprising at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, said at least one enclosure also encloses these at least one Lithiumdendritenabbau device, and preferably wherein the at least one Lithiumdendritenabbau Device has at least one material which is designed to reduce lithium dendrites, in particular to reduce.

This has the advantage that resulting or already formed lithium dendrites can be reduced, preferably minimized, in particular degraded.

In one embodiment of the electrochemical cell, the at least one lithium dendrite decomposition device, preferably designed as a lithium dendrite decomposition layer, is at least partially disposed on at least parts of the surface of the at least one cladding, said surface of the cladding of the positive electrode closest to the cladding and / or negative Electrode and / or separator faces, and / or the at least one separator, and / or the at least one positive electrode, and / or the at least one negative electrode.

In one embodiment of the electrochemical cell, the at least one lithium dendrite removal device, preferably embodied as a lithium dendrite degradation layer, has at least one material which is designed to reduce, in particular degrade, lithium dendrites, wherein said at least one material comprises or consists of sulfur-containing compounds.

This has the advantage that the sulfur-containing material can react with the lithium dendrites in particular to form lithium sulfide, whereby lithium dendrites can be avoided in their formation process, or already formed lithium dendrites can be degraded.

In one embodiment of the electrochemical cell, the at least one lithium dendrite degradation device, preferably designed as a lithium dendrite degradation layer, at least one material which is designed to reduce lithium dendrites, especially to degrade, this at least one material selected from the group consisting of: elemental sulfur , in particular elemental sulfur in the form of S ₈ ; polysulfides; inorganic, organic or polymeric, sulfur-containing compounds, in particular trifluoromethanesulphonate salts; or mixtures of the aforementioned substances.

In one embodiment of the electrochemical cell, the negative electrode comprises at least one material which is designed as an electrochemical active material and which is selected from amorphous graphite, crystalline graphite, carbonaceous materials, lithium metal, lithium metal alloys, titanates, silicates, silicon, silicon alloys, tin , Tin alloys, or mixtures thereof.

In one embodiment of the electrochemical cell, the positive electrode comprises at least one material configured as an electrochemical active material and which is selected from: at least one compound including LiMPO ₄ , wherein M is at least one transition metal cation selected from manganese, iron, cobalt , Titanium or a combination of these elements; or at least one spinel-type lithium metal oxide or lithium metal mixed oxide, wherein the metal is selected from cobalt, manganese or nickel; or at least one lithium metal oxide or lithium metal mixed oxide in a type other than spinel type, wherein the metal is selected from cobalt, manganese or nickel; or mixtures thereof.

In one embodiment of the electrochemical cell, the separator or the separator material is selected from: a separator or a separator material, which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting, wherein the carrier on at least one side with an inorganic Material is coated, wherein as at least partially permeable support an organic material is used, which is designed as a non-woven fabric, wherein the organic material is configured in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET), wherein the nonwoven with an inorganic Material is coated, which is preferably permeable to ions, and preferably in a temperature range of -40 ° C to 200 ° C is permeable to ions, wherein the inorganic material preferably at least one compound selected from the group of oxides, phosphates, S sulfates, titanates, silicates, aluminosilicates comprising at least one of the elements zirconium, aluminum, lithium, particularly preferably aluminum oxide, wherein preferably inorganic material has particles with a maximum diameter below 100 nm, or a separator or a A separator material comprising or consisting of polymer fibers selected from the group of polymers consisting of polyethylene terephthalate, polyolefin, polyetherimide, polyamide, polyacrylonitrile, polycarbonate, polysulfone, polyethersulfone, polyvinylidene fluoride, polystyrene, or mixtures of two or more of these polymers, or a separator or a separator material comprising or consisting of inorganic material.

Furthermore, the invention encompasses a lithium dendrite degradation device for use in an electrochemical cell, wherein the at least one lithium dendrite degradation device is configured as a lithium dendrite degradation layer.

In one embodiment of the lithium dendrite decomposition device, the lithium dendrite decomposition device has at least one material which is designed to reduce, in particular decompose, lithium dendrites, wherein this at least one material is selected from the group consisting of elemental sulfur, in particular elemental sulfur in the form of S ₈ (especially chains or rings); polysulfides; inorganic, organic or polymeric, sulfur-containing compounds, in particular trifluoromethanesulphonate salts; or mixtures thereof.

This has the advantage that the sulfur-containing material can react with the lithium dendrites in particular to form lithium sulfide, whereby lithium dendrites can be avoided in their formation process, or already formed lithium dendrites can be degraded.

• • Bereitstellen mindestens einer positiven Elektrode, wobei die positive Elektrode zumindest ein Material aufweist, welches als elektrochemisches Aktivmaterial ausgestaltet ist,
• • Bereitstellen mindestens einer negativen Elektrode, wobei die negative Elektrode zumindest ein Material aufweist, welches als elektrochemisches Aktivmaterial ausgestaltet ist,
• • Bereitstellen mindestens eines Separator, welcher die mindestens eine positive Elektrode von der mindestens einen negativen Elektrode beabstandet, insbesondere elektrische isoliert, und
• • Bereitstellen mindestens einer Umhüllung, insbesondere ausgestaltet als Folienumhüllung, welche die mindestens eine negative Elektrode und die mindestens eine positive Elektrode und den mindestens einen Separator zumindest teilweise, vorzugsweise vollständig umschließt
• • Zusammenbau der elektrochemischen Zelle,

die elektrochemische Zelle weiterhin mindestens eine Lithiumdendritenabbau-Vorrichtung, vorzugsweise ausgestaltet als Lithiumdendritenabbau-Schicht, aufweist, wobei die mindestens eine Umhüllung diese mindestens eine Lithiumdendritenabbau-Vorrichtung ebenfalls umschließt, und wobei vorzugsweise die mindestens eine Lithiumdendritenabbau-Vorrichtung zumindest ein Material aufweist, welches ausgestaltet ist Lithiumdendriten zu reduzieren, insbesondere abzubauen.Furthermore, the invention encompasses a method for producing an electrochemical cell according to the invention comprising the following steps:

• Providing at least one positive electrode, wherein the positive electrode comprises at least one material which is designed as an electrochemical active material,
• Providing at least one negative electrode, wherein the negative electrode comprises at least one material which is designed as an electrochemical active material,
• Providing at least one separator which spaces the at least one positive electrode from the at least one negative electrode, in particular electrically isolates, and
• Provision of at least one envelope, in particular designed as a foil envelope, which encloses the at least one negative electrode and the at least one positive electrode and the at least one separator at least partially, preferably completely
• Assembly of the electrochemical cell,

the electrochemical cell further comprises at least one lithium dendrite degradation device, preferably configured as a lithium dendrite degradation layer, said at least one enclosure also enclosing said at least one lithium dendrite removal device, and wherein preferably said at least one lithium dendrite degradation device comprises at least one material configured To reduce lithium dendrites, in particular to reduce.

Furthermore, the invention covers the use of the electrochemical cell according to the invention for supplying energy to mobile information devices, tools, electrically powered automobiles, for automobiles with hybrid drive or for stationary energy storage.

Electrochemical cell

An "electrochemical cell" in the sense of the present invention means any type of device for the electrical storage of energy.

The term thus includes in particular electrochemical cells of the primary or secondary type, but also other forms of energy storage, such as capacitors.

Furthermore, the term "electrochemical cell" is also to be understood as meaning a corresponding battery, since the battery generally consists of a series or series connection of individual electrochemical cells. Accordingly, an electrochemical cell is always to be understood as meaning the corresponding battery having at least one electrochemical cell. Furthermore, the term "battery" can also be used synonymously with the term "accumulator".

For the purposes of the present invention, the electrochemical cell is preferably a lithium-ion battery / cell.

The electrochemical cell comprising at least one positive electrode, at least one negative electrode and at least one separator which spaces the positive electrode from the negative electrode is further at least partially surrounded, preferably completely surrounded by at least one sheath.

Lithiumdendritenabbau device

For the purposes of the present invention, the term "lithium dendrite degradation device" is to be understood as an apparatus which is designed such that the resulting or formed lithium dendrites are advantageously carried by Interaction with the lithium dendrite degradation device, in particular by chemical reaction between the lithium dendrites and at least one, contained in the lithium dendrites degradation device, reduced, in particular degraded.

Preferably, the lithium dendrite removal device is attached to locations within the electrochemical cell, where lithium dendrites may arise, ie in particular in the immediate vicinity, in particular in, on or on the at least one positive electrode and / or the at least one negative electrode, in particular in the vicinity or in material contact with the electrochemical active material of the at least one positive electrode and / or the at least one negative electrode.

• • der mindestens einen Umhüllung, wobei besagte Oberfläche der Umhüllung der, zur Umhüllung nächstliegenden, positiven Elektrode und/oder negativen Elektrode und/oder Separator zugewandt ist, und/oder
• • des mindestens einen Separators, und/oder
• • der mindestens einen positiven Elektrode, und/oder
• • der mindestens einen negativen Elektrode.

In one embodiment, the at least one lithium dendrite degradation device is at least partially, in particular completely, arranged on at least parts of the surface:

• The at least one sheath, said surface of the sheath facing the positive electrode closest to the sheath and / or the negative electrode and / or separator, and / or
• • the at least one separator, and / or
• The at least one positive electrode, and / or
• • the at least one negative electrode.

In a preferred embodiment, the lithium dendrite removal device is formed as a layer (lithium dendrite degradation layer). However, the lithium dendrite degradation device can also take any other conceivable or suitable for use in an electrochemical cell spatial structure.

For the purposes of the present invention, the term "layer" or "lithium dendrite degradation layer" is to be understood as meaning a substantially flat-formed body or material, the extent in one dimension being at least 50%, preferably at least 70%, preferably at least 90%, preferably at least 99%, but not 100% smaller than the spread in the other two dimensions.

The at least one lithium dendrite removal device can comprise a material, in particular a compound / a substrate, or a plurality of materials or at least partially or completely consist of materials. Preferably, the lithium dendrite degradation device has at least in part materials that may be present in an electrochemical cell. Such materials may include, for example, sulfur-containing materials, polymeric materials, materials comprising polymeric precursors (eg, monomers), electrochemical active material, conductivity additives, liquid or gel materials, metallic materials, or mixtures thereof.

In one embodiment, the at least one lithium dendrite degradation device preferably comprises at least partially polymeric materials, in particular separator materials.

In a particularly preferred embodiment, the at least lithium dendrite removal device has at least one material which is designed to reduce, in particular to decompose, lithium dendrites, this having at least one material having compounds, in particular containing or consisting of sulfur-containing compounds.

Preferably, said at least one material is selected from the group consisting of: elemental sulfur, in particular elemental sulfur in the form of S ₈ ; Sulfides, in particular polysulfides; inorganic, organic or polymeric, sulfur-containing compounds, in particular trifluoromethanesulphonate salts; or mixtures thereof. For the purposes of the present invention, the term "compound" also includes elemental sulfur, which in any case occurs in some modifications as covalently bonded rings or chains.

For the purposes of the present invention, the term "sulfur" is to be understood as meaning sulfur which is present essentially in the oxidation state "0", that is to say as elemental sulfur. It is not excluded that shares of sulfur also exist at least partially in other oxidation states.

For the purposes of the present invention, "sulfide"("suicidematerial" is to be used synonymously with "sulfide") is a compound in which at least one sulfur atom has an oxidation state which is different from "0", in particular "-1". or "-2". According to this convention, "sulfide" is synonymous with "sulfur anion" or "polysulfide" (where "polysulfide material" can also be used synonymously with "polysulfide"), where the prefix "poly-" is intended to mean that this compound has at least two or more more, in particular 2, 3, 4, 5, 6, 7 or 8 to have sulfur atoms, wherein at least one sulfur atom formally has an oxidation state which is different from "0", in particular "-1" or "-2" and wherein further sulfur atoms may formally have the oxidation state "0". Examples of sulfides or polysulfides are S ^2- , S ₃ ^2- , S ₄ ^2- , S ₅ ^2- , S ₆ ^2- , S ₇ ^2- , S ₈ ^2- , S ₂ ^- , S ₃ ^- , S ₄ ^- . As counterions, that is as cations, in particular metal cations are suitable, for example alkali metal cations, preferably lithium, alkaline earth metal cations, Subgroup metal cations, such as iron.

For the purposes of the present invention, "sulfur-containing" means both sulfur as defined above and sulfide or polysulfide as defined above or mixtures thereof.

This is advantageous in particular because the lithium dendrites are reduced by the reaction of elemental lithium from which lithium dendrites are composed with the sulfur which is contained in the abovementioned chemical compounds to form lithium polysulfides and / or lithium sulfide, in particular Li ₂ S. in particular be degraded (eg 2 Li + S → Li ₂ S).

It is furthermore advantageous that the resulting or formed lithium-sulfur compound (s), in particular Li ₂ S, have electrically insulating properties, ie can act as an electrical insulator within the electrochemical cell. In particular, when the lithium dendrite degradation device is present on at least parts of the at least one envelope, said surface of the envelope facing the envelope closest to the positive electrode and / or negative electrode and / or separator, and / or the at least one separator the electrically insulating property of resulting or formed lithium-sulfur compounds, in particular Li ₂ S advantageous because this reduces the risk of direct contact between the electrically conductive material of the sheath and the adjacent electrode, preferably can be prevented. Envelopes for electrochemical cells, as defined below, have dimensionally stable materials, in particular metals, on which the electrodes are electrically insulated in order to prevent undesired or unplanned contacts between the electrodes and the electrically conductive material, in particular the metal of the enclosure.

The lithium dendrite degradation device can be in solid, in particular in film-like or powder form or in liquid form. For example, separator material may be provided with sulfur-containing material to form a sheet-like lithium dendrite removal device.

In particular, in the case of lithium dendrite decomposition using sulfur-containing compounds, as mentioned above, sulfide compounds, in particular polysulfide compounds such as Li ₂ S _x with 2 ≦ x ≦ 8, can be formed as decomposition products. These compounds are soluble in non-aqueous organic electrolytes and could thus diffuse within the electrochemical cell, adversely affecting the performance of the electrochemical cell. Therefore, it is advantageous to integrate a sulfide scavenger layer into the electrochemical cell in addition to the lithium dendrite degrading device according to the invention, in particular layer, especially when a non-aqueous, organic electrolyte is used in the electrochemical cell. Preferably, the separator is then designed as a sulfide scavenger layer. Preferably, the nonwovens which can be used in the separator are produced from nanofibers of the polymers used, as explained below, whereby nonwovens are formed which have a high porosity with formation of small pore diameters. Thus, the risk of short circuit reactions can be further reduced, as well as the risk of unwanted diffusion of polysulfide anions through the separator.

wrapping

• • der Begrenzung der mindestens einen positiven Elektrode, der mindestens einen negativen Elektrode und des mindestens einen Separators und optional, des zumindest einen Elektrolyten gegenüber der Umgebung dient
• • dem Schutz der mindestens einen positiven Elektrode, der mindestens einen negativen Elektrode und des mindestens einen Separators und optional, des zumindest einen Elektrolyten gegenüber schädlichen Einflüssen aus der Umgebung, insbesondere dem Schutz vor Wasser aus der Umgebung dient,
• • dem Austritt von Material aus der mindestens einen positiven Elektrode, der mindestens einen negativen Elektrode und des mindestens einen Separators und/oder optional, des zumindest einen Elektrolyten in die Umgebung entgegenwirkt,
• • vorzugsweise die mindestens eine positive Elektrode, die mindestens eine negative Elektrode und den mindestens einen Separators und/oder optional, den zumindest einen Elektrolyten im Wesentlichen gasdicht und/oder fluiddicht umschließt.

An "envelope" within the meaning of the present invention means a device which, in particular

• The limitation of the at least one positive electrode, which serves at least one negative electrode and the at least one separator and optionally, the at least one electrolyte with respect to the environment
• The protection of the at least one positive electrode, which serves at least one negative electrode and the at least one separator and optionally, the at least one electrolyte against harmful influences from the environment, in particular the protection against water from the environment,
• The escape of material from the at least one positive electrode, which counteracts at least one negative electrode and the at least one separator and / or optionally, the at least one electrolyte into the environment,
• Preferably the at least one positive electrode enclosing at least one negative electrode and the at least one separator and / or optionally, the at least one electrolyte substantially gas-tight and / or fluid-tight.

In one embodiment, the enclosure has at least two shell parts, a first shell part and a second shell part. The first shell part may completely or partially envelop the second shell part. Preferably, the first and the second shell part may adjoin one another. The first shell part and the second shell part can preferably be positively and / or positively and / or materially connected to each other at least partially to the at least one positive electrode, the at least one negative electrode and the at least one separator and optionally, the at least one electrolyte at least partially surrounded.

Preferably, the shell parts at least partially adapt to the shape / contour of the at least one positive electrode, the at least one negative electrode and the at least one separator and optionally, the at least one electrolyte.

The shell parts may preferably have the same or different properties, for example, the first shell part may have good thermal conductivity properties, and the second shell part may have good insulating properties. The shell parts can at least partially have the same or different materials or be constructed from it. For example, one shell part can be made flexible, while the other is configured rigid.

In one embodiment, at least one shell part may be partially film-like, preferably the at least one shell part has composite material.

In one embodiment, the envelope is in particular formed in one piece. Preferably, the interior of the envelope is at least partially made of composite material which comprises at least one polymer, preferably polypropylene. It should not be ruled out that the interior of the envelope has only one material, or is constructed only in one piece. Rather, it is also preferably possible that the interior of the envelope is designed in several parts, which also includes a multi-layered design, such as in a composite material, and that the interior of the envelope has at least two materials, for example at least two polymers, or at least one Polymer and at least one metal. Preferably, the exterior of the enclosure is at least partially made of composite material. It should not be ruled out that the exterior of the envelope has only one material, or is constructed only in one piece. Rather, it is preferably also possible that the exterior of the enclosure is designed in several parts, which also includes a multi-layered design, such as in a composite material, and that the exterior of the enclosure comprises at least two materials, for example at least two polymers, or at least one Polymer and at least one metal. Preferably, the interior and the exterior of the enclosure are made of the same material, preferably a composite material.

In a preferred embodiment, the wrapper is configured as a film wrapper and formed in one or two parts, and comprises or consists of a flexible composite material, wherein the composite material comprises at least one polymer, preferably two polymers, in particular polyethylene, polypropylene and / or polyethylene terephthalate, and at least one Metal, in particular aluminum. Electrochemical cells having such flexible sheaths are known to those skilled in the art as "pouch cell" or "coffee bag cell". The composite material has in particular a layered structure, preferably with the following sequence polymer 1 / metal / polymer 2, wherein preferably at least one polymer is designed as a thermoplastic polymer, for example as a polyolefin, such as polyethylene or polypropylene, to form a substantially gas-tight and / or or fluid-tight enclosure of the at least one positive electrode, the at least one negative electrode and the at least one separator and / or optionally, the at least one electrolyte to achieve. This is preferably achieved by welding two polymer layers of the sheath which come to rest on one another.

In a further embodiment, the envelope is designed rigid. Electrochemical cells which have such rigid casings are known to the person skilled in the art under the name "hard case cell". Preferably, such a rigid casing metal, in particular aluminum, copper, iron or steel.

Negative electrode

The term "negative electrode" in the sense of the present invention means that the electrode emits electrons when connected to a consumer, for example an electric motor. Thus, according to this convention, the negative electrode is the anode.

Preferably, the negative electrode has at least one electrochemical active material which is suitable for incorporation and / or removal of redox components, in particular of lithium ions.

In one embodiment, the electrochemical active material of the negative electrode is selected from amorphous graphite, crystalline graphite, carbonaceous materials, lithium metal, lithium metal alloys, titanates, silicates, silicon, silicon alloys, tin, tin alloys, or mixtures thereof.

In addition to the electrochemical active material, the negative electrode preferably also has at least one further additive, preferably an additive for increasing the conductivity, for example based on carbon, for example carbon black, and / or a redox-active additive which, if the electrochemical cell is overcharged, destroys the electrochemical cell reduced electrochemical active material, preferably minimized, preferably prevented.

Preferably, the negative electrode has a metallic substrate. This metallic substrate serves as a collector for the electrons. Preferably, this metallic substrate is at least partially coated with at least one electrochemical active material.

In one embodiment, the active material applied to the metallic substrate comprises a binder which is capable of improving the cohesion in the active material and / or the adhesion between electrochemical active material and a metallic substrate. Preferably, such a binder comprises a polymer, preferably a fluorinated polymer, preferably polyvinylidene fluoride on, which is sold under the trade names Kynar ^® or Dyneon ^®.

Positive electrode

The term "positive electrode" means that the electrode receives electrons when connected to a consumer, such as an electric motor. Thus, according to this convention, the positive electrode is the cathode.

The positive electrode of the electrochemical cell preferably has at least one electrochemical active material which is suitable for incorporation and / or removal of redox components, in particular of lithium ions.

In one embodiment, the positive electrode electrochemical material is selected from at least one oxide, preferably a composite oxide, which has one or more elements selected from nickel, manganese, cobalt, phosphorus, iron or titanium.

In one embodiment, the positive electrode comprises a compound having the formula LiMPO ₄ wherein M is at least one transition metal cation, preferably a transition metal cation of the first series of transition metals of the Periodic Table of the Elements.

The at least one transition metal cation is preferably selected from the group consisting of manganese, iron, nickel, cobalt or titanium or a combination of these elements. The compound preferably has an olivine structure, preferably parent olivine, with iron or cobalt being particularly preferred, preferably LiFePO ₄ or LiCoPO ₄ . However, the compound may also have a structure different from the olivine structure.

In a further embodiment, the positive electrode comprises an oxide, preferably a transition metal oxide, or a transition metal mixed oxide, preferably of the spinel type, preferably a lithium manganate, preferably LiMn ₂ O ₄ , a lithium cobaltate, preferably LiCoO ₂ , or a lithium Nickelate, preferably LiNiO ₂ , or a mixture of two or three of these oxides. However, the oxides can also be different from the spinel type.

Further preferably, in addition to the aforementioned transition metal oxides, the positive electrode may comprise exclusively a lithium transition metal mixed oxide containing manganese, cobalt and nickel, preferably a lithium cobalt manganate, preferably LiOoMnO ₄ , preferably a lithium nickel manganate, preferably LiNi _0.5 Mn _1.5 O ₄ , preferably a lithium-nickel-manganese-cobalt oxide, preferably LiNi _0.33 Mn _0.33 Co _0.33 O ₂ , or a lithium-nickel-cobalt oxide, preferably LiNiCoO ₂ , which in Spinel type or different from the spinel type may be present.

In addition to the electrochemical active material, the positive electrode preferably has at least one further additive, preferably an additive for increasing the conductivity, for example based on carbon, for example carbon black, and / or a redox-active additive which reduces the destruction of the electrochemical active material when the electrochemical cell is overcharged , preferably minimized, preferably prevented.

Preferably, the positive electrode comprises a binder which is capable of improving the cohesion in the active material and / or the adhesion between electrochemical active material and a metallic substrate. Preferably, such a binder comprises a polymer, preferably a fluorinated polymer, preferably polyvinylidene fluoride on, which is sold under the trade names Kynar ^® or Dyneon ^®.

Preferably, the positive electrode has a metallic substrate ("collector"). Preferably, this metallic substrate is at least partially coated with electrochemical active material.

substratum

The term "substrate" in the context of the present invention relates to that component of an electrochemical cell which is known as "electrode carrier" and "collector" and essentially serves the supply or removal of electrodes to / from the active material. In the present case, the metallic substrate is suitable for applying electrochemical active composition and is substantially more metallic Nature, preferably completely metallic nature, thus contains "free" electrons.

Preferably, at least one electrode has at least partially a metallic substrate. Preferably, this metallic substrate is at least partially designed as a film or as a network structure or as a fabric.

In one embodiment, a metallic substrate comprises copper or a copper-containing alloy. In a further embodiment, a metallic substrate comprises aluminum. In one embodiment, the metallic substrate can be configured as a film, mesh structure or fabric, which preferably comprises at least partially plastics.

Preferably, up to 30%, preferably up to 50%, preferably up to 70%, preferably up to 100%, of the total surface of a metallic substrate has at least one layer which has at least one electrochemical active material which is suitable for incorporation and / or removal of lithium ions suitable is.

separator

"Separator" (the term "separator material" is synonymous with "separator") in the sense of the present invention is a material which separates the at least one negative electrode and the at least one positive electrode of the electrochemical cell, in particular spaced apart from one another, especially electrically isolated.

In the following, the term "nonwoven" becomes synonymous with terms such as "nonwoven fabrics", "nonwoven material"; "Knitted"; "Nonwoven" or "felt" used. Instead of the term "unwoven" the term "not woven" is used.

The separator used for the electrochemical cell is preferably permeable to lithium ions. This has the advantage that the ion transport of the lithium ions between the at least one positive and the at least one negative electrode can be ensured.

On the other hand, the separator is preferably insulating for electrons, i. H. the separator is preferably not or poorly electronically conductive. This has the advantage that a direct flow of electrons between the positive and the negative electrode is prevented, since this would lead to a short circuit of the battery.

In one embodiment, the separator comprises polymer fibers selected from the group of polymers consisting of polyethylene glycol terephthalate, polyolefin, polyetherimide, polyamide, polyacrylonitrile, polycarbonate, polysulfone, polyethersulfone, polyvinylidene fluoride, polystyrene, polyester, polyimide, polyamideimide, polyether, polyphenylene sulfide, aramid or mixtures of two or more of these polymers.

Polyolefins are, for example, polyethylene, polypropylene, polytetrafluoroethylene, polyvinylidene fluoride. Halogen-containing polyolefins such as polytetrafluoroethylene, polyvinylidene fluoride, polyvinyl chloride are also usable.

Polyesters are, for example, polyethylene terephthalate or polybutylene terephthalate.

Polyamides are for example the known types PA 6.65 and PA 6.0, known under the brand names Perlon Nylon ^® and ^®.

Aramids are, for example meta-aramid and para-aramid, which are known under the brand names Nomex ^® and Kevlar ^®.

Polyamide are known for example under the Markenbezeichung Kermel ^®.

Preferred polymer fibers are polymer fibers of polyethylene terephthalate.

Preferably, the separator consists of a polyolefin or of a mixture of polyolefins. Particularly preferred in this embodiment is then a separator which consists of a mixture of polyethylene and polypropylene.

Preferably, such separators have a layer thickness of 3 to 14 .mu.m.

The polymers are preferably in the form of nonwoven fiber webs, ie in the form of nonwoven polymer fibers which are not electrically conductive. Such nonwovens are produced in particular by spinning processes with subsequent solidification.

The polymer fibers preferably have an average diameter of 0.1 to 10 .mu.m, preferably from 1 to 4 .mu.m.

In a preferred embodiment, the separator comprises a nonwoven, preferably a nonwoven web of nonwoven polymer fibers, which are coated on one or both sides with an inorganic material, preferably with an inorganic material which is permeable to ions.

The term "coating" in the context of the invention also means that the inorganic material is not only on one side or both sides of the Fleece can be located, but also within the fleece.

The inorganic material is preferably ion-permeable, preferably ionically conductive in a temperature range of -40 ° C to 200 ° C, i. H. ionic for lithium ions. The inorganic material used for the coating is preferably at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates of at least one of zirconium, aluminum, silicon or lithium.

In a preferred embodiment, the inorganic material comprises or consists of alumina or zirconia or alumina and zirconia.

In one embodiment, a separator may be used, which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting. This support is coated on at least one side with an inorganic material. As an at least partially permeable carrier an organic material is used, which is designed as a non-woven fleece, so from non-woven polymer fibers. The organic material is in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET). The nonwoven is coated with an inorganic material, which is preferably permeable to ions, preferably in a temperature range of -40 ° C to 200 ° C is permeable to ions. The inorganic material preferably has at least one compound from the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates with at least one of the elements zirconium, aluminum, lithium, particularly preferably aluminum oxide. The inorganic material preferably has particles with a largest diameter below 100 nm.

Such a separator is marketed in Germany, for example, under the trade name "Separion ^®" by the company Evonik AG. Methods for producing such separators are known from the prior art, for example from the EP 1 017 476 B1 . WO 2004/021477 and WO 2004/021499 ,

In the following, particularly preferred embodiments of the separator used and the advantages are summarized in particular in terms of safety.

In principle, too large pores and holes in separators used in secondary batteries can lead to an internal short circuit. The battery can then discharge itself very quickly in a dangerous reaction. In this case, such large electrical currents can occur that a closed battery cell can even explode in the worst case. For this reason, the separator can contribute significantly to the safety or lack of security of a lithium high performance or lithium high energy battery.

Polymer separators prevent i. a. above a certain temperature (the so-called "shut-down temperature", which is typically about 120 ° C) any current transport through the electrolyte. This happens because at this temperature, the pore structure of the separator collapses and all pores are closed. The fact that no ions can be transported, the dangerous reaction that can lead to an explosion, comes to a standstill. However, if the cell continues to be heated due to external circumstances, the so-called "break-down temperature" is exceeded at approx. 150 to 180 ° C. From this temperature it comes in conventional separators to melt the separator, which contracts. In many places in the battery cell, there is now a direct contact between the two electrodes and thus to a large internal short circuit. This leads to an uncontrolled reaction, which can end with an explosion of the cell, or the resulting pressure must be reduced by a pressure relief valve (a rupture disc), often under fire phenomena.

In the separator used in the electrochemical cell according to the invention comprising a nonwoven fabric made of nonwoven polymer fibers and the inorganic coating, it can only come to shutdown (shutdown), when the polymer melted by the high temperature of the carrier material and penetrates into the pores of the inorganic material and this closes it. On the other hand, there is no such break-down (collapse) as the inorganic particles ensure that complete melting of the separator can not occur. This ensures that there are no operating states in which a large-area short circuit can occur. Due to the type of nonwoven used, which has a particularly suitable combination of thickness and porosity, separators can be produced that can meet the requirements for separators in high-performance batteries, especially lithium high-performance batteries. By the simultaneous use of precisely matched in their particle size oxide particles for the preparation of the porous (ceramic) coating a particularly high porosity of the finished separator is achieved, the pores are still small enough to unwanted growth of "lithium whiskers" through to prevent the separator.

Due to the high porosity of the separator, however, care must be taken to ensure that no or as little dead space as possible is created in the pores.

This happens because due to the high porosity in combination with the small thickness of the separator, it is possible to impregnate the separator completely or at least almost completely with the electrolyte, so that no dead spaces in individual areas of the separator and thus in certain windings or laminations of the Battery cells may arise in which there is no electrolyte. This is achieved in particular by the compliance of the particle size of the oxide particles, the resulting separators are free or virtually free of closed pores, in which the electrolyte can not penetrate.

The separators used for the invention also have the advantage that partially attach to the inorganic surfaces of the separator material, the anions of the conducting salt, which leads to an improvement in the dissociation and thus to a better ionic conductivity in the high current range.

Another not inconsiderable advantage of the separator is the very good wettability. Due to the hydrophilic ceramic coating, wetting with electrolytes takes place very rapidly, which likewise leads to improved conductivity.

The separator used for the electrochemical cell according to the invention, comprising a flexible nonwoven with a porous inorganic coating on and in this nonwoven, the material of the nonwoven being selected from (nonwoven) non-electrically conductive polymer fibers, is also characterized in that the nonwoven a thickness of less than 30 microns, a porosity of more than 50%, preferably from 50 to 97% and a pore radius distribution, wherein at least 50% of the pores have a pore radius of 75 to 150 microns.

Particularly preferably, the separator has a nonwoven, which has a thickness of 30 microns and less, preferably from 5 to 30 microns, preferably a thickness of 10 to 20 microns. Also particularly important is a homogeneous distribution of pore radii in the web as indicated above. An even more homogeneous pore radius distribution in the nonwoven, in combination with optimally matched oxide particles of a certain size, leads to an optimized porosity of the separator. The thickness of the substrate has a great influence on the properties of the separator, since on the one hand the flexibility but also the sheet resistance of the electrolyte-impregnated separator depends on the thickness of the substrate. Due to the small thickness, a particularly low electrical resistance of the separator is achieved in the application with an electrolyte. The separator itself has a very high electrical resistance, since it itself must have insulating properties. In addition, thinner separators allow increased packing density in a battery pack so that one can store a larger amount of energy in the same volume.

Preferably, the web has a porosity of 60 to 90%, more preferably from 70 to 90%. The porosity is defined as the volume of the web (100%) minus the volume of the fibers of the web, ie the proportion of the volume of the web that is not filled by material.

The volume of the fleece can be calculated from the dimensions of the fleece. The volume of the fibers results from the measured weight of the fleece considered and the density of the polymer fibers. The large porosity of the substrate also allows a higher porosity of the separator, which is why a higher uptake of electrolytes with the separator can be achieved. In order to obtain a separator having insulating properties, it preferably has non-electrically conductive fibers of polymers as defined above as polymer fibers for the nonwoven fabric. Preferably, these are selected from the polymers listed above, preferably polyacrylonitrile (PAN), polyesters, such as. As polyethylene terephthalate (PET) and / or polyolefin (PO), such as. As polypropylene (PP) or polyethylene (PE), or mixtures of such polyolefins.

The polymer fibers of the nonwovens preferably have a diameter of from 0.1 to 10 .mu.m, more preferably from 1 to 4 .mu.m.

Particularly preferred flexible nonwovens have a basis weight of less than 20 g / m ² , preferably from 5 to 10 g / m ² .

Preferably, the nonwoven is flexible and has a thickness of less than 30 microns.

In a preferred embodiment, the separator has a, on and in the non-woven, porous, electrically insulating, ceramic coating. The porous inorganic coating on and in the nonwoven preferably has oxide particles of the elements Li, Al, Si and / or Zr with an average particle size of 0.5 to 7 μm, preferably of 1 to 5 μm and very particularly preferably of 1 , 5 to 3 microns on.

Particularly preferably, the separator has a porous inorganic coating on and in the nonwoven, the aluminum oxide Particles. Preferably, these have an average particle size of 0.5 to 7 microns, preferably from 1 to 5 microns and most preferably from 1.5 to 3 microns. In one embodiment, the alumina particles are bonded to an oxide of elements Zr or Si.

In order to achieve the highest possible porosity, preferably more than 50% by weight and more preferably more than 80% by weight of all particles are within the abovementioned limits of average particle size. As already described above, the maximum particle size is preferably 1/3 to 1/5 and particularly preferably less than or equal to 1/10 of the thickness of the nonwoven used.

Preferably, the separator, preferably comprising a nonwoven and a ceramic coating, a porosity of 30 to 80%, preferably from 40 to 75% and particularly preferably from 45 to 70%. The porosity refers to the achievable, ie open pores. The porosity can be determined by the known method of mercury porosimetry or can be calculated from the volume and density of the starting materials used, if it is assumed that only open pores are present. The separators used for the electrochemical cell according to the invention are further distinguished by the fact that they can have a tensile strength of at least 1 N / cm, preferably of at least 3 N / cm and very particularly preferably of 3 to 10 N / cm. The separators can preferably be bent without damage to any radius down to 100 mm, preferably down to 50 mm and most preferably down to 1 mm.

The high tensile strength and the good bendability of the separator have the advantage that changes in the geometries of the electrodes occurring during the charging and discharging of a battery can be through the separator without being damaged. The flexibility also has the advantage that this makes the separator also in combination with wound electrodes, which are used for example commercially standardized winding cells, operational. In such standardized winding cells, the electrodes / separator layers are spirally wound together in a standardized size and contacted.

In one embodiment, it is possible to design the separator to have the shape of a concave or convex sponge or pad, or the shape of wires or a felt. This embodiment is well suited to compensate for volume changes in the battery.

In a further embodiment, the polymer fleece used in the separator has a further polymer. Preferably, this polymer is disposed between the separator and the negative electrode and / or the separator and the positive electrode, preferably in the form of a polymer layer.

In one embodiment, the separator is coated with this polymer on one or both sides.

Said polymer may be in the form of a porous membrane, i. H. as a film, or in the form of a nonwoven, preferably in the form of a nonwoven fabric of non-woven polymer fibers.

These polymers are preferably selected from the group consisting of polyester, polyolefin, polyacrylonitrile, polycarbonate, polysulfone, polyethersulfone, polyvinylidene fluoride, polystyrene, polyetherimide.

Preferably, the further polymer is a polyolefin. Preferred polyolefins are polyethylene and polypropylene.

The separator is preferably coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as a nonwoven, that is to say as nonwoven polymer fibers.

Preferably, a non-woven of polyethylene terephthalate is used in the separator, which is coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably also present as non-woven, so as non-woven polymer fibers.

Particular preference is given to a separator of the above-described type of separation which is coated with one or more layers of the further polymer, preferably of the polyolefin, which is preferably likewise present as a nonwoven, that is to say as nonwoven polymer fibers.

The coating with the further polymer, preferably with the polyolefin, can be achieved by gluing, lamination, by a chemical reaction, by welding or by a mechanical connection. Such polymer composites and processes for their preparation are known from EP 1 852 926 known.

The fiber diameters of the polyethylene terephthalate fleece are preferably larger than the fiber diameters of the further polymer fleece, preferably the polyolefin fleece, with which the separator is coated on one or both sides.

Preferably, the nonwoven made of polyethylene terephthalate then has a higher pore diameter than the nonwoven, which is made of the other polymer.

Preferably, the nonwovens usable in the separator are made of nanofibers of the polymers used, whereby nonwovens are formed which have a high porosity with formation of small pore diameters. Thus, the risk of short circuit reactions can be further reduced, as well as the risk of unwanted diffusion of polysulfide anions through the separator.

The use of a polyolefin in addition to the polyethylene terephthalate ensures increased safety of the electrochemical cell, since in unwanted or excessive heating of the cell, the pores of the polyolefin contract and the charge transport through the separator is reduced or terminated. Should the temperature of the electrochemical cell increase to such an extent that the polyolefin begins to melt, the polyethylene terephthalate effectively counteracts the melting together of the separator and thus an uncontrolled destruction of the electrochemical cell.

In a further embodiment of the separator, this consists of an inorganic material. Preferably, the inorganic material used are oxides of magnesium, calcium, aluminum, silicon and titanium, as well as silicates and zeolites, borates and phosphates. Such materials for separators and processes for the preparation of the separators are in EP 1 783 852 disclosed. In a preferred embodiment of this embodiment of a separator, the separator consists of magnesium oxide.

In a further embodiment of the separator 50 to 80 wt .-% of the magnesium oxide by calcium oxide, barium oxide, barium carbonate, lithium, sodium, potassium, magnesium, calcium, barium phosphate or by lithium, sodium, potassium borate, or Mixtures of these compounds, be replaced.

The separators of this embodiment preferably have a layer thickness of 4 to 25 μm.

electrolyte

"Electrolyte" (the term "electrolyte material" is synonymous with "electrolyte") in the sense of the present invention is a material which acts as an internal conductor to transport the charge carriers, in particular the lithium ions from the positive electrode to the negative electrode and vice versa - And discharging the electrochemical cell is involved.

In one embodiment, the electrochemical cell has at least one electrolyte.

An electrolyte preferably comprises a liquid and a conducting salt.

Preferably, the liquid is a solvent, in particular an organic solvent for the conducting salt. Preferably, the electrolyte is then present as an electrolyte solution.

Suitable electrolytes are known in the art.

In particular, as the electrolyte, a non-aqueous electrolyte consisting of at least one organic solvent and at least one alkali ion-containing, preferably lithium ion-containing inorganic or organic salt can be used.

In principle, all solvents known to the person skilled in the art which are used in electrolytes of electrochemical cells can serve as the organic solvent.

Suitable solvents are preferably organic and inert. Preferably, the solvent is selected from ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl methyl carbonate (EMC), methyl propyl carbonate, butyl methyl carbonate, ethyl propyl carbonate, cyclopentanones, methyl formate (MF). , Methyl acrylate (MA), methyl butyrate (MB), methyl acetate, ethyl acetate (EA), 1,2-dimethoxyethane, 3-methyl-1,3-oxazolidin-2-one, γ-butyrolactone, tetrahydrofuran (THF), 2-methyltetrahydrofuran , 1,3-Dioxylane, 1,3-Propanesultone, Sulfulan, Ethylmethylsulfone (EMS), Tetramethylenesulfone (TMS), Butylsulfone (BS), Ethylvinylsulfone (EVS), Dimethylsulfoxide, 1-Fluoro-2- (methylsulfonyl) benzene (FS) , Acetonitrile, nitromethane or phosphoric acid esters, or mixtures of two or more of these solvents.

Preferred conductive salts are alkali metal-containing salts which have inert anions and which are non-toxic. Preferably, the alkali metal-containing, preferably lithium-ion-containing conductive salt has one or more counterions selected from AsF ₆ ^- , PF ₆ ^- , PF ₃ (C ₂ F ₅ ) ₃ ^- , PF ₃ (CF ₃ ) ₃ ^- , BF ₄ ^- , BF ₂ (CF ₃ ) ₂ ^- , BF ₃ (CF ₃ ) ^- , [B (COOCOO) ₂ ] ^- , [B (C ₆ H ₅ ) ₄ ] ^- , Cl ^- , Br ^- , AlCl ₄ ^- , CF ₃ SO ₃ ^- , C ₄ F ₉ SO ₃ ^- , [(SO ₂ C _x F _{2x + 1} ) ₃ C] ^- where 0 ≤ x ≤ 8, preferably [(CF ₃ SO ₂ ) ₃ C] ^- , [ (CF ₃ SO ₂ ) ₂ N] ^- , [(C ₂ F ₅ SO ₂ ) N] ^- , [(CN) ₂ N] ^- , ClO ₄ ^- , SiF ₆ ^- , or mixtures of two or more of these salts.

Preferably, the separator of the electrochemical cell is impregnated with the electrolyte. In one embodiment, the separator is impregnated with an electrolyte which is designed as an ionic liquid.

Ionic liquids are ionic compounds which are in a liquid state at room temperature. Ionic liquids consist of anions and cations, with the size ratio between cations and anions chosen so that they do not dispose at room temperature in a crystal lattice, whereby a liquid at room temperature salt can be obtained, which is referred to as ionic liquid.

The ionic liquid typically has "large" organic cations, such as the ethylmethylimidazolium cation, and relatively "small" anions, such as the tetrafluoroborate anion.

Preferably, ionic liquids are used which have cationic imidazole-containing derivatives, in particular the cation ethyl-methyl-imidazolium. Further examples of useful cations which may also be alkylated are imidazolium, pyridinium, pyrrolidinium, guanidinium, uronium, thiuronium, piperidinium, morpholinium, sulfonium, ammonium and phosphonium cations.

Preferred anions can be selected from the group AlCl ₄ , Al ₂ Cl ₇ , F, F × HF, NO ₂ , NO ₃ , BF ₄ , AlF ₄ , PF ₆ , AsF ₆ , SbF ₆ , NbF ₆ , TaF ₆ , WF ₇ , CH ₃ CO ₂ , CF ₃ CO ₂ , C ₃ F ₇ CO ₂ , CH ₃ SO ₃ , CF ₃ SO ₃ , C ₄ F ₉ SO ₃ , (CF ₃ CO) (CF ₃ SO ₃ ) N, CF ₃ SO ₂ ) ₂ N, (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ ) N, (C ₂ F ₅ SO ₂ ) ₂ N, (CF ₃ SO ₂ ) ₃ C, (CN) ₂ N, (CN) ₃ C, CF ₃ BF ₃ , C ₂ F ₅ BF ₃ , C ₃ F ₇ BF ₃ , C ₄ F ₉ BF ₃ or mixtures thereof.

Examples of ionic liquids which may be mentioned are: N-methyl-N-propylpiperidinium bis (trifluoromethylsulfonyl) imide, N-methyl-N-butyl-pyrrolidinium bis (trifluoromethylsulfonyl) imide, N-butyl-N-trimethyl-ammonium bis (Trifluoromethylsulfonyl) imide, triethylsulfonium bis (trifluoromethylsulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) -ammonium bis (trifluoromethylsulfonyl) -imide.

Furthermore, the electrolyte may have adjuvants that are commonly used in electrolytes for lithium-ion batteries. For example, these are free-radical scavengers such as biphenyl, flame retardant additives such as organic phosphoric acid esters or hexamethylphosphoramide, or acid scavengers such as amines.

Furthermore, the electrolyte preferably contains additives preferably phenylene carbonate, fluorine-containing or non-fluorine-containing lithium organoborates, for example lithium difluoro (oxalato) borate (LiDFOB) or lithium bis (oxalato) borate (LiBOB) and fluorine-containing or non-fluorine-containing lithium organophosphates, for example lithium tetrafluoro (oxalato) phosphate (LiTFOP) or lithium tris (oxalato) phosphate (LiTOP), which may affect the formation of the SEI layer on the electrodes.

In one embodiment, the electrolyte is configured as a polymer electrolyte which, in addition to the abovementioned salts, solvents, auxiliaries and additives, has a polymer matrix. The polymer or polymer blend for the polymer matrix is preferably selected from the polymers that can be used for separators.

In one embodiment, a polymer electrolyte of a lithium salt and polyethylene oxide is used.

Production of the electrochemical cell

The electrochemical cell according to the invention may be constructed from at least one positive electrode, at least one negative electrode, at least one electrolyte and at least one separator according to principles known in the art and commonly used for the production of lithium ion batteries.

• • Bereitstellen mindestens einer positiven Elektrode, wobei die positive Elektrode zumindest ein Material aufweist, welches als elektrochemisches Aktivmaterial ausgestaltet ist,
• • Bereitstellen mindestens einer negativen Elektrode, wobei die negative Elektrode zumindest ein Material aufweist, welches als elektrochemisches Aktivmaterial ausgestaltet ist,
• • Bereitstellen mindestens eines Separator, welcher die mindestens eine positive Elektrode von der mindestens einen negativen Elektrode beabstandet, insbesondere elektrische isoliert, und
• • Bereitstellen mindestens einer Umhüllung, insbesondere ausgestaltet als Folienumhüllung, welche die mindestens eine negative Elektrode und die mindestens eine positive Elektrode und den mindestens einen Separator zumindest teilweise, vorzugsweise vollständig umschließt
• • Zusammenbau der elektrochemichen Zelle

wobei die elektrochemische Zelle weiterhin mindestens eine Lithiumdendritenabbau-Vorrichtung, vorzugsweise ausgestaltet als Lithiumdendritenabbau-Schicht, aufweist, wobei die mindestens eine Umhüllung diese mindestens eine Lithiumdendritenabbau-Vorrichtung ebenfalls umschließt, und wobei vorzugsweise die mindestens eine Lithiumdendritenabbau-Vorrichtung zumindest ein Material aufweist, welches ausgestaltet ist Lithiumdendriten zu reduzieren, insbesondere abzubauen.In a further embodiment, the invention encompasses a method for producing an electrochemical cell according to at least one of the preceding claims, comprising the following steps:

• Providing at least one positive electrode, wherein the positive electrode comprises at least one material which is designed as an electrochemical active material,
• Providing at least one negative electrode, wherein the negative electrode comprises at least one material which is designed as an electrochemical active material,
• Providing at least one separator which spaces the at least one positive electrode from the at least one negative electrode, in particular electrically isolates, and
• Provision of at least one envelope, in particular designed as a foil envelope, which encloses the at least one negative electrode and the at least one positive electrode and the at least one separator at least partially, preferably completely
• • Assembly of the electrochemical cell

wherein the electrochemical cell further comprises at least one lithium dendrite degradation device, preferably embodied as a lithium dendrite decomposition layer, wherein the at least one enclosure likewise encloses these at least one lithium dendrite removal device, and wherein preferably the at least one lithium dendrite removal device has at least one material which is designed to reduce, in particular degrade, lithium dendrites.

The timing and technique of incorporation of the conductive dendritic degradation device may vary depending on the technique used to assemble the electrochemical cell.

For example, it is possible to provide the lithium dendrite removal device in the form of a sheet-like device, and to integrate it into the electrode stack as an additional layer during assembly of the electrode stack.

Furthermore, it is possible to provide the finished electrode stack with a lithium dendrite removal device before the electrode stack is enclosed by the cover. This can be achieved, for example, by wrapping the finished electrode stack with a foil-like lithium dendrite removal device.

However, it is also possible, for example, to apply or introduce a pulverulent or liquid lithium dendrite removal device onto the electrode stack or into the electrode stack.

Furthermore, it is possible that z. B, the, the electrode stack facing surface of the enclosure is equipped with the lithium dendrite removal device.

Operation and use of the electrochemical cell

The electrochemical cell according to the invention preferably has a capacity of at least 3 ampere hours [Ah], more preferably at least 5 Ah, more preferably at least 10 Ah, more preferably at least 20 Ah, more preferably at least 50 Ah, even more preferably at least 100 Ah , more preferably of at least 200 Ah, more preferably of at most 500 Ah. This embodiment offers the advantage of an improved service life of the consumer powered by the electrochemical cell.

Preferably, the electrochemical cell according to the invention is designed, at least temporarily, preferably for at least one hour, an electric current of at least 50 A, more preferably of at least 100 A, more preferably of at least 200 A, more preferably of at least 500 A, more preferably of at most 1000 A up. This embodiment offers the advantage of improved performance of the consumer powered by the electrochemical cell.

Preferably, the electrochemical cell according to the invention is operable at least temporarily, preferably for at least one hour, between -40 ° C and 100 ° C, more preferably between -20 ° C and 80 ° C, more preferably between -10 ° C and 60 ° C, more preferably between 0 ° C and 40 ° C, on. This embodiment offers the advantage of an unrestricted installation or use of the electrochemical cell according to the invention for supplying a consumer, in particular a motor vehicle or a stationary system or machine.

The electrochemical cell preferably has an energy density of at least 50 Wh / kg, more preferably of at least 100 Wh / kg, more preferably of at least 200 Wh / kg, more preferably of more than 500 Wh / kg, in particular 1500 Wh / kg. Preferably, the electrode assembly comprises lithium ions. This embodiment offers the advantage of an improved energy density of the electrochemical cell.

In a further embodiment, the invention encompasses the use of the electrochemical cell according to the invention for supplying power to mobile information devices, tools, electrically powered automobiles, hybrid-powered automobiles or stationary energy storage devices.

According to a preferred embodiment, the electrochemical cell is provided for installation in a vehicle with at least one electric motor. Preferably, the electrochemical cell is provided for supplying this electric motor. Particularly preferably, the electrochemical cell is provided to supply at least temporarily an electric motor of a drive train of a hybrid or electric vehicle. This embodiment offers the advantage of improved supply of the electric motor.

According to a further preferred embodiment, the electrochemical cell is intended for use in a stationary battery, in particular in a buffer memory, as a device battery, industrial battery or starter battery. The nominal charge capacity of the electrochemical cell for these applications is preferably at least 3 Ah, more preferably at least 10 Ah. This embodiment offers the advantage of an improved supply of a stationary consumer, in particular a stationary mounted electric motor.

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 5961672 [0007]
• EP 1017476 B1 [0095]
• WO 2004/021477 [0095]
• WO 2004/021499 [0095]
• EP 1852926 [0125]
• EP 1783852 [0130]

Claims (11)

Electrochemical cell comprising: at least one negative electrode, wherein the negative electrode comprises at least one material, which is designed as an electrochemical active material, and at least one positive electrode, wherein the positive electrode comprises at least one material which is designed as an electrochemical active material, and At least one separator, which spaces the at least one positive electrode from the at least one negative electrode, in particular electrically insulated, and at least one envelope, in particular designed as a foil envelope, which comprises the at least one negative electrode and the at least one positive electrode and the at least one positive electrode Separator at least partially, preferably completely encloses characterized in that the electrochemical cell further comprises at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, wob ei the at least one sheath also encloses these at least one lithium dendrite removal device, and wherein preferably the at least one lithium dendrite removal device comprises at least one material which is designed to reduce lithium dendrites, in particular to degrade them. Electrochemical cell according to claim 1, characterized in that the at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, at least partially disposed on at least parts of the surface: • the at least one enclosure, said surface of the enclosure, the closest to the enclosure , the positive electrode and / or negative electrode and / or separator, and / or • the at least one separator, and / or • the at least one positive electrode, and / or • the at least one negative electrode. Electrochemical cell according to at least one of the preceding claims, characterized in that the at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, comprising at least one material which is designed to reduce lithium dendrites, in particular to reduce, said at least one material having sulfur-containing compounds or consists of. Electrochemical cell according to at least one of the preceding claims, characterized in that the at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, comprising at least one material which is designed to reduce lithium dendrites, in particular to reduce, this at least one material is selected from the group consisting of: elemental sulfur, in particular elemental sulfur in the form of S ₈ ; polysulfides; inorganic, organic or polymeric, sulfur-containing compounds, in particular trifluoromethanesulphonate salts; or mixtures thereof. Electrochemical cell according to at least one of the preceding claims, characterized in that the negative electrode comprises at least one material which is designed as an electrochemical active material and which is selected from amorphous graphite, crystalline graphite, carbonaceous Materiaalien, lithium metal, lithium metal alloys, titanates, silicates , Silicon, silicon alloys, tin, tin alloys, or mixtures thereof. Electrochemical cell according to at least one of the preceding claims, characterized in that the positive electrode comprises at least one material which is designed as an electrochemical active material and which is selected from: a. at least one compound LiMPO ₄ , wherein M is at least one transition metal cation selected from manganese, iron, cobalt, titanium or a combination of these elements; or b. at least one spinel-type lithium metal oxide or lithium metal mixed oxide, wherein the metal is selected from cobalt, manganese or nickel; or c. at least one lithium metal oxide or lithium metal mixed oxide in a type other than spinel type, wherein the metal is selected from cobalt, manganese or nickel; or mixtures thereof. Electrochemical cell according to at least one of the preceding claims, characterized in that the separator or the separator material is selected from: d. a separator or a separator material, which consists of an at least partially permeable carrier, which is not or only poorly electron-conducting, wherein the carrier is coated on at least one side with an inorganic material, wherein as at least partially permeable carrier an organic material is used , which is designed as a non-woven fabric, wherein the organic material is configured in the form of polymer fibers, preferably polymer fibers of polyethylene terephthalate (PET), wherein the nonwoven fabric is coated with an inorganic material, which is preferably permeable to ions, preferably in a temperature range of -40 ° C to 200 ° C is permeable to ions, wherein the inorganic material preferably at least one compound the group of oxides, phosphates, sulfates, titanates, silicates, aluminosilicates comprising at least one of the elements zirconium, aluminum, lithium, more preferably alumina, wherein preferably the inorganic material has particles with a maximum diameter below 100 nm, or e. a separator or a separator material comprising or consisting of polymer fibers selected from the group of polymers consisting of polyethylene terephthalate, polyolefin, polyetherimide, polyamide, polyacrylonitrile, polycarbonate, polysulfone, polyethersulfone, polyvinylidene fluoride, polystyrene, or mixtures of two or more of these polymers , or f. a separator or a separator material comprising or consisting of inorganic material. A lithium dendrite degradation device for use in an electrochemical cell, characterized in that the at least one lithium dendrite degradation device is configured as a lithium dendrite degradation layer. A lithium dendrite degradation device according to claim 8 for use in an electrochemical cell, characterized in that the lithium dendrite degradation device comprises at least one material configured to reduce, particularly degrade, lithium dendrites, said at least one material selected from the group consisting of: elemental sulfur , in particular elemental sulfur in the form of S ₈ ; polysulfides; inorganic, organic or polymeric, sulfur-containing compounds, in particular trifluoromethanesulphonate salts; or mixtures thereof. Method for producing an electrochemical cell according to at least one of the preceding claims 1 to 7, comprising the following steps: providing at least one positive electrode, wherein the positive electrode comprises at least one material which is designed as an electrochemical active material, providing at least one negative electrode, wherein the negative electrode comprises at least one material which is designed as an electrochemical active material, providing at least one separator which spaces the at least one positive electrode from the at least one negative electrode, in particular electrical insulation, and at least one envelope, in particular designed as a foil envelope which at least partially, preferably completely surrounds the at least one negative electrode and the at least one positive electrode and the at least one separator n cell, characterized in that the electrochemical cell further comprises at least one Lithiumdendritenabbau device, preferably designed as a lithium dendrite decomposition layer, wherein the at least one sheath also encloses these at least one Lithiumdendritenabbau device, and preferably wherein the at least one Lithiumdendritenabbau device at least a material which is designed to reduce lithium dendrites, in particular to reduce. Use of the electrochemical cell according to at least one of claims 1 to 7 for power supply for mobile information devices, tools, electrically powered automobiles, for automobiles with hybrid drive or for stationary energy storage.