EP2705559A1

EP2705559A1 - Electrochemical cell

Info

Publication number: EP2705559A1
Application number: EP12723370.8A
Authority: EP
Inventors: Tim Schaefer
Original assignee: Li Tec Battery GmbH
Current assignee: Li Tec Battery GmbH
Priority date: 2011-05-05
Filing date: 2012-04-25
Publication date: 2014-03-12
Also published as: KR20140035908A; JP2014519144A; WO2012150012A1; DE102011100607A1

Abstract

The invention relates to an electrochemical cell, comprising at least one negative electrode and at least one positive electrode, wherein at least one electrode comprises at least one substrate and at least one layer comprising active material, wherein fine structure elements are arranged at least partially between said layer comprising active material and the substrate.

Description

Electrochemical cell

Hereby, the entire contents of the priority application DE 10 2011 100 607 by reference is part of the present application.

Description

The present invention relates to an electrochemical cell, wherein at least one electrode has at least one substrate and at least one layer with active material, wherein fine structure elements are at least partially present or arranged between this layer and the substrate. The cell can preferably be used for driving a vehicle with an electric motor, preferably with hybrid drive or in "plug-in" operation.

Electrochemical cells, especially lithium secondary batteries, because of their high energy density and high capacity, are used as energy stores in mobile information devices, e.g. Mobile phones, in tools or in electrically powered automobiles, as well as in automobiles with hybrid drive application. Despite these very different fields of application of electrochemical cells, all the cells used, but especially those for driving 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 ,

The longevity of electrochemical cells is often dependent on the aging of the electrodes. In the aging process lose the electrochemical cells typically in capacity and / or performance. This process takes place to a greater or lesser extent in most common electrochemical cells, and is highly dependent on the conditions of use (temperature, storage conditions, state of charge, etc.), but also the quality and processing of the materials during the electrochemical cell manufacturing process , Thus, a high-quality processing of very pure materials can lead to very long-lived electrochemical cells, which age only a little over a longer period of time, so lose relatively little capacity and performance.

Since the purity of materials used are often set physical or chemical limits, for example due to synthesis processes, it is a primary goal of battery manufacturers to obtain by optimizing the manufacturing process of the electrodes always higher quality and thus more durable electrochemical cells, such as described in the document EP 2 006 942.

In particular, the adhesion of the electrochemical active material on the surface of the metallic substrate ("collector") contributes substantially to the quality and aging resistance of an electrochemical cell Chromosulphuric acid substrate, which improves the adhesion of the electrochemical active material on the surface of the metallic substrate, and thus reduces the delamination of the electrochemical active material from the metal collector / substrate A drawback to this process is the use of chromic acid, which is toxic to humans and the environment , and also represents an intolerable impurity for further processing in electrochemical cells.

Furthermore, it is known that the electrochemical active material, both the anode and the cathode, in the charging process or discharge process a Experience volume change. The amount of volume change during the charging or discharging process is partly dependent on the composition of the electrochemical active material. For example, an anode of lithium metal or a lithium metal alloy may experience a larger volume change during charging and discharging processes than other electrochemical active materials. It is known from the prior art that embedding electrochemical active material in a carbon matrix effectively reduces the volume change (Jusef Hassoun, Bruno Scrosati, Angew Chem Chem, Ed., 2010, 49, 1-5). The reduction of the volume change of the electrochemical active material during charging or discharging processes is of importance for the long-term stability of the cell, since the volume change can cause a delamination of the individual layers (active material, collector, separator) and thus the performance the cell decreases over time - so the electrochemical cell ages.

An object of the present invention is therefore to provide a stabilized electrochemical cell which is comparatively durable. 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, which has at least one negative electrode and at least one positive electrode, wherein at least one electrode has at least one substrate and at least one layer with active material, wherein at least partially between this layer with active material and substrate the fine structure elements are arranged.

In one embodiment, the at least one layer of active material is at least partially by means of the fine structure elements with the at least one Substrate is at least partially connected so that the at least one layer is substantially non-destructive free from the at least one substrate.

In one embodiment, the at least one layer is at least partially connected to the fine structure elements in such a way that the fine structure elements can not be detached from the at least one layer substantially non-destructively.

In one embodiment, the at least one layer of active material at least partially undergoes a reduced, preferably no change in volume during charging and / or discharging processes by means of the fine structure elements.

In one embodiment, the at least one layer of active material at least partially comprises materials used in an electrochemical cell, preferably selected from polymeric materials, materials comprising polymeric precursors (eg, monomers), electrochemical active material, separator materials, conductivity additives, liquid or gel materials, metallic materials or mixtures thereof.

In one embodiment, the fine structure elements comprise at least one material which is substantially different from the active material, and / or which is substantially different from the binder used for active materials.

In one embodiment, the fine structure elements or the at least one layer and the fine structure elements are formed by using a porous template or a template layer having negative recesses of the fine structure elements. In one embodiment, the negative electrode at least partially comprises an electrochemical active material 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, the positive electrode at least partially comprises at least one electrochemical active material selected from:

• at least one compound LiMP0 ₄ , where M is at least one

Transition metal cation is selected from manganese, iron, cobalt,

Titanium or a combination of these elements; or

• at least one lithium metal oxide or lithium metal mixed oxide in

Spinel type, 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 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.

• Provide at least one positive electrode

• Provide at least one negative electrode Providing an intermediate layer which is arranged between the positive electrode and the negative electrode

Assembly of the electrochemical cell according to the sequence of positive electrode / intermediate layer / negative electrode,

wherein at least one electrode at least partially at least one layer having active material and at least one substrate, wherein at least partially fine structure elements are arranged between the at least one layer and the at least one substrate.

Use of the electrochemical cell according to the invention for supplying energy to a consumer, in particular in mobile information devices, tools, electrically powered automobiles or automobiles with hybrid drive.

An "electrochemical cell" in the sense of the present invention means any device for the electrical storage of energy. The term defines in particular electrochemical cells of the primary or secondary type, but also other forms of energy storage, such as capacitors. In the present case, an electrochemical cell is preferably to be understood as meaning a lithium-ion battery / cell.

In a preferred embodiment, the electrochemical cell has at least one positive electrode, one negative electrode, and at least one separator separating the positive from the negative electrode.

Negative electrode

The term "negative electrode" means that the electrode emits electrons when connected to a consumer, such as 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.

Preferably, in addition to the electrochemical active material, the negative electrode 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 reduces the destruction of the electrochemical active material when the electrochemical cell is overcharged , 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, which is sold under the tradenames 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 LiMP0 ₄ , where 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 LiNi0 ₂ , or a mixture of two or three of these oxides. However, the oxides can also be different from the spinel type.

Further preferably, the positive electrode in addition to the aforementioned transition metal oxides exclusively a lithium -, transition metal mixed oxide containing manganese, cobalt and nickel, preferably a lithium-cobalt manganate, preferably LiCoMnO ₄ , preferably a lithium-nickel manganate, preferably LiNio _, sMnvsO _A , preferably a lithium-nickel-manganese-cobalt oxide, preferably LiNi _0, 3 ₃ Mno _, 33Coo, 33O ₂ , or a lithium-nickel-cobalt oxide, preferably LiNiCoO ₂ , which in the spinel type or deviating from 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, which is sold under the tradenames 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

For the purposes of the present invention, the term "substrate" refers to that component of an electrochemical cell which is known as "electrode carrier" and "collector" and essentially serves to supply or discharge electrodes to / from the active material Applying electrochemical active composition suitable and is substantially metallic nature, preferably completely metallic nature, so 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.

Layer The term "layer" is to be understood as meaning a substantially flat 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 layer can comprise one or more materials or at least partially or completely consist of materials. Preferably, the layer at least partially comprises materials which may be present in an electrochemical cell. Such materials may be, for example, 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 layer preferably comprises at least partially polymeric materials.

For the purposes of the present invention, the at least one layer at least partially comprises active material, preferably electrochemical active material. In a preferred embodiment, the at least one layer at least partially comprises active material, preferably electrochemical active material and polymeric materials.

Polymeric materials may be, for example, materials which are used as binders, at least partially in separators or polymer electrolytes in electrochemical cells.

In a particularly preferred embodiment, the at least one layer preferably comprises at least partially materials which can be used as binders (also called binders) in electrochemical cells. Preferably, up to 5%, preferably up to 10%, preferably up to 15%, preferably up to 20% of the at least one Layer of materials that can be used as binders in electrochemical cells. Preferably, such materials are selected from the group: polyvinylidene fluoride (PVdF), styrene-butadiene rubber (also called: butadiene-styrene copolymer; SBR) or poly (tetrafluoroethylene) (PTFE) or mixtures thereof.

In a particularly preferred embodiment, the at least one layer preferably comprises at least partially materials which can be used at least partially in separators in electrochemical cells. Preferably, such materials are selected from the group of polyolefins, such as polypropylene (PP) or polyethylene (PE), polyethylene glycol terephthalate, polyetherimide, polyamide, polyacrylonitrile, polycarbonate, polysulfone, polyvinylidene fluoride, polystyrene or mixtures thereof.

In a particularly preferred embodiment, the at least one layer preferably comprises at least partially materials which can at least partially be used in polymer electrolytes in electrochemical cells. Preferably, such materials are selected from the group consisting of polyethers such as poly (ethylene oxide) (PEO) or poly (propylene oxide) (PPO), polyamines such as poly (ethyleneimine) (PEI) or poly (acrylonitrile) (PAN). or the polysulfides such as poly (alkylene sulfide) (PAS) or mixtures thereof. Fine structure element

For the purposes of the present invention, the term "fine structure element" is to be understood in particular as meaning three-dimensional not completely symmetrical bodies, which are preferably fibrous, hair-shaped, reticulated, fork-like, root-like or the like. An advantage and the characteristic of fine structure elements characteristic of the present invention is that layers with fine structure elements have a higher surface area per mass and / or volume than layers without such fine structure elements.

Many surfaces, due to typically non-covalent interactions (that is, interactions not associated with the formation of a chemical bond), exhibit a "typical adhesiveness", which is typical of the particular surface, and some surfaces have relatively high adhesiveness, such as cling films, for example very thin (about 0.01 pm) and at the same time very soft (ie have elastic properties) Comparable plastic films of the same material without such fine structure elements (for example, of greater thickness) have a significantly lower adhesiveness.

By using fine structure elements, an advantageous increase in the surface area (per mass and / or volume) is achieved for the layer according to the invention. By means of the fine structure elements, the surface of the layer according to the invention is increased by up to 100%, preferably by up to 200%, preferably by up to 500%, preferably by up to 750% or more, in comparison to a layer which has no fine structure elements.

Now, if a larger surface area is present, non-covalent interactions of the fine structure element can advantageously affect its environment. This has the advantage that thereby the adhesiveness of the layer is increased by the presence of the fine structure element.

The effectiveness of this technical effect is known from the nature of the Reptiles of the Gekkoiden family, which with their adhesively shaped feet also find support on very smooth surfaces. According to the invention, at least one electrode of an electrochemical cell has at least one layer (with active material) and at least one substrate, wherein fine structure elements are arranged at least partially between this at least one layer and the at least one substrate. This has the advantage that the adhesivity can act within the layer and / or to regions of the cell adjacent to the layer, thus increasing the adhesion of the electrode to a substrate such as the separator or the electrode carrier, thereby stabilizing the electrode, and the Longevity of the electrode is improved.

The term "adhesiveness" is to be understood as meaning the property of a surface (of a material, article, etc.), of adhering to a second surface (eg of a material, article, etc.) The term "adhesiveness" thus describes the adhesion properties of a surface (eg, a layer, a material, article, etc.) High adhesiveness therefore means that the adhesion properties of a surface (eg, a layer, a material, article, etc.) are particularly pronounced Thus, the surface (eg, a layer, a material, an article, etc.) adheres substantially well to a second surface (eg, a layer, a material, an article, etc.) The two surfaces are That is, it is only after application of a certain force F _a b to separate the second surface (eg, a layer, a material, article, etc.) from having a lower adhesiveness than the first surface (eg a material, object, etc.). The force F _ab is greater than the adhesion force, which in turn is influenced by the sum of all interactions of the first surface with the second surface. Preferably, these interactions are essentially non-covalent. In addition to non-covalent interactions, covalent interactions, electrostatic interactions, capillary forces, magnetic interactions and the like may occur. Ä. Act between a first and a second surface. By the term "non-covalent" are preferably hydrogen bonds, dipole-dipole interactions (keesom interactions), charge-transfer interactions, ττ-ττ electron interactions, cation-Tr interactions, hydrophobic (lipophilic) interactions - Disperse interactions (London dispersion interactions), Debye interactions, and preferred to understand Van der Waals interactions.

Van der Waals interactions are to be understood as forces which interact between the atoms and / or molecules of a first surface with the atoms and / or molecules of at least one second surface according to the following equation.

WVDW = -

The adhesion force as a measure of the adhesiveness of a surface can be determined, for example, according to ASTM D1876, while a theoretical estimation of the adhesion force can be carried out, for example, according to the theory established by Kendall, Roberts and Johnson.

In one embodiment, the fine structure elements have at least one first material, and the at least one layer has at least one second material which is identical in composition and / or quality to the at least first material.

In one embodiment, the fine structure elements comprise at least one first material, and the at least one layer comprises at least one second material, which is different from the at least first material, with regard to composition and / or quality. In a preferred embodiment, the fine structure elements essentially comprise polymeric materials, preferably binders, and the at least one layer has at least partially active material, preferably electrochemical active material.

In a further preferred embodiment, the fine structure elements essentially comprise polymeric materials, preferably binders, and the at least one layer has at least partially active material, preferably electrochemical active material, conductivity additives and polymeric materials.

Preferably, the at least one layer is at least partially preferably fully bonded (i.e., surrounding) to the fine structure elements so that the at least one layer is substantially non-destructively detachable from the at least one substrate.

Preferably, at least one electrode of an electrochemical cell has a layer which has fine structure elements. In a preferred embodiment, at least one electrode has a layer which has fine structure elements, and this layer is preferably designed as a surface layer of the at least one electrode.

Preferably, in one embodiment, up to 30%, preferably up to 50%, preferably up to 70%, preferably up to 100%, of the volume of at least one electrode has a layer comprising fine structure elements.

Preferably, a fine structure element has at least one or a plurality of elongated sections having an average thickness and average length. By the term "elongate section" is meant a substantially three-dimensionally formed body or material, the propagation in two dimensions being at least 50%, preferably at least 70%, preferably at least 90%, preferably at least 99%, but not around 100% less than the propagation in a third dimensions.

Preferably, in a preferred embodiment, the order of magnitude of the largest spread, preferably the average length and / or the average thickness of the fine structure elements in the micrometer range, is furthermore preferred in the nanometer range. Preferably, the fine structure elements have a maximum extent, preferably an average thickness of greater than 0 nm to 10 nm, preferably up to 50 nm, preferably up to 100 nm, preferably up to 200 nm, preferably up to 500 nm, preferably from greater than to 1 μηι, preferably up to 3pm, preferably up to 5μητι, preferably up to 10μπν Preferably, the fine structure elements have an average largest dimension, preferably length of greater than 0 nm up to 300 nm, preferably up to 600 nm, preferably up to 1 μηι, preferably up to 5 μm, preferably up to 20 μm, preferably up to 50 μm, preferably up to 70 μm, preferably up to 20 μm, preferably up to 250 μm, preferably up to 500 μm.

In one embodiment, an average ratio average thickness average length of the elongate portion of the fine structure elements ([nm]: [nm] or [μιη]: [μηι]) of up to 1: 2, preferably from up to 1: 5, preferably from up to 1:10, preferably from up to 1:30, preferably from up to 1:50, preferably from up to 1: 100, preferably from up to 1: 200.

In one embodiment, a fine structure element preferably consists of a first material or a first material mixture, and the layer has the same or qualitatively and / or quantitatively the same first material or the same first material mixture or consists thereof. In a further embodiment, the at least one layer (without the fine structure elements) comprises second materials or second material mixtures which are different from the first material or the first material mixture or consists of these second materials or second material mixtures.

The fine structure elements preferably comprise materials which have an E-modulus (for example according to DIN 53457) of greater than 0 MPa up to 10 MPa, preferably up to 100 MPa, preferably up to 1000 MPa, preferably up to 5000 MPa, preferably up to to 10,000 MPa, preferably up to 30,000 MPa.

In a preferred embodiment, the fine structure elements comprise polymeric materials.

The layer preferably has a density of fine structure elements (FE) of greater than 0 FE / cm ³ to 10 ³ FE / cm ³ , preferably up to 10 ⁵ FE / cm ³ , preferably up to 10 ⁷ FE / cm ³ , preferably up to 10 ¹⁰ FE / cm ³ . In a preferred embodiment, the at least one layer is at least partially connected at least partially by means of the fine structure elements to a metallic substrate such that the at least one layer can not be detached from the metallic substrate substantially non-destructively. In a preferred embodiment, the layer is at least partially designed so that by means of the fine structure elements, the electrochemical cell a reduced, preferably no change in volume during loading and / or unloading processes undergoes.

In one embodiment, the fine structure elements or the fine structure elements and the at least one layer are produced as follows:

A template layer is provided.

The master layer preferably comprises a substantially soft, deformable material, which is preferably inelastic, preferably form-retaining, such as wax.

A template is provided which essentially has fine structure elements on at least one surface. The fine structure elements of the template are preferably designed as the fine structure elements of the at least one layer to be designed later.

Preferably, the original comprises material which is substantially harder than the material of the master layer, such as a metal or a metal-containing material.

The original is then pressed or rolled onto the master layer or brought into contact with the master layer by other methods, whereby the fine structural elements, located on the surface of the master, at least partially penetrate into the master layer. The template is used as a positive body. As a result, negative recesses of the fine structure elements located on the surface of the original are produced in the document layer. The master layer thus has a negative of the fine structure elements as they are on the template on.

The original is peeled from the master layer to give the prints of the fine features as negative in the master layer. This template layer Having the negative of the fine structure elements is now used to form the fine structure elements or the at least one layer and the fine structure elements. For this purpose, material which has the fine structure elements or the at least one layer and the fine structure elements at least partially applied to the master layer, comprising a negative of the fine structure elements, preferably so that the material at least partially, preferably completely fills the negative recesses of the fine structure elements of the master layer. This can be done, for example, by pouring or spraying on material, which has the fine structure elements or the at least one layer and the fine structure elements at least partially, in a liquid state. Another way to apply the material to the master layer is to coat the material, which is particularly advantageous when the material is designed substantially pasty.

This may be followed by a knocking or shaking step whereby the document layer is vibrated with applied material or tapped against a device to ensure the most complete possible penetration of the material into the negative recesses, and any trapped gases, such as air bubbles, if possible completely remove.

But there are also other methods known in the art, conceivable to apply the material to the master layer and to achieve a complete penetration of the material into the negative recess. The material which has the fine structure elements or the at least one layer and the fine structure elements at least partially, can thereby substantially exclusively in the negative recesses of the document layer can be introduced, which can be done for example by subsequent removal or dumping of excess material which is located on the master layer, but outside the negative recesses. But it is also possible that the material is located in the negative recesses of the document layer, and further forms a layer of thickness x, which also extends in areas between the negative recesses, and so at least two negative recesses, each containing the material, materially connected to each other ,

Furthermore, it is possible that the negative recesses of the master layer have at least one first material, and further a layer of thickness x is formed, which preferably has at least one second material, which is different from the at least first material located in the negative recesses, and which also extends in areas between the negative recesses, and thus preferably at least two negative recesses, each containing the at least first material, materially interconnected. This attachment step may be followed by a solidification step. By solidification step is meant that measures are carried out which solidify the material comprising the fine structure elements or the at least one layer and the fine structure elements at least partially. The solidification can be realized, for example, by evaporation of solvent, at least partial drying, pressing of the material or polymerization of the material. The solidification of the material is preferably carried out to the extent that the fine structure elements or the at least one layer and the fine structure elements are at least partially formed, which in a subsequent separation step is preferably to be separated as completely as possible from the original layer nondestructive. The solidification step may be followed by a separation step in which the master layer and the fine structural elements formed as described above or the formed at least one layer and the fine structural elements are separated from each other.

In this case, the fine structure elements or the at least one layer and the fine structure elements are preferably separated from the template layer having negative recesses of the fine structure elements in a non-destructive manner. The separation can take place by subtracting the fine structure elements or the at least one layer and the fine structure elements of the template layer having negative recesses of the fine structure elements. This has the advantage that the template layer comprising negative recesses of the fine structure elements can also be separated non-destructively from the fine structure elements or the at least one layer and the fine structure elements in order, after a possible cleaning step, for re-application of material to form fine structure elements or the at least one layer and the fine structure elements can be provided for use in electrochemical cells.

However, it is also possible for the master layer comprising negative recesses of the fine structural element to be separated from the fine structural elements or the at least one layer and the fine structural elements in a non-destructive manner. This may be done, for example, by heating the master layer to or above a temperature (which may correspond to the boiling or melting temperature of the master layer material), and thus liquefying or vaporizing the master layer. It is important to ensure that the temperature is lower than the melting temperature or boiling point or sublimation of the material which have the fine structure elements or the at least one layer and the fine structure elements substantially. A further possibility of separating the template layer comprising negative recesses of the fine structure element non-destructively from the fine structure elements or the at least one layer and the fine structure elements, it is the template layer chemically (for example by solvents or reagents which react with the material of the master layer) or physically (for example radiation or Evaporation), whereby the molecular structure of the material constituting the master layer is dissolved. In a further embodiment, the fine structure elements or the at least one layer containing fine structure elements are produced as follows:

A porous template with a thickness a is provided. As a porous template, any porous material can be used. Preferably, the porous template has porous, inelastic and / or rigid and / or dimensionally stable material. This has the advantage that the porous template does not deform substantially when pressure or vacuum is applied.

Such a porous template preferably comprises at least partially metal, ceramic, glass, hard plastic or other substantially inelastic, rigid materials or mixtures thereof. Particularly advantageous is the use of porous membranes as a porous template, as they are used in processes of filtration, in particular microfiltration, ultrafiltration and nanofiltration, such as glass or ceramic filters. Particularly preferred are porous templates having the designation (according to DIN / ISO 4793) P500, preferably P250, preferably P160, preferably P100, preferably P40, preferably P40, preferably P16, and furthermore preferably P1, 6. Particular preference is furthermore given to porous templates (according to ASTM / BS standard) "Extra coarse", preferably "Coarse", preferably "medium", preferably "fine", preferably "very fine", furthermore preferably "ultra fine".

Further preferred are porous templates whose pores are substantially not in contact with each other, for example by lateral crosslinks. Such porous pads preferably have pores having a substantially as short as possible straight connection between a first end of a pore, and a second end of the same pore spaced therefrom.

In a particularly preferred embodiment, the porous template used is separator material, in particular ceramic separator material (such as the material "Separion" sold by Evonik.) Material which has the fine structure elements or the at least one layer and the fine structure elements at least partially is applied to this template.

Subsequently, the material is at least partially introduced into the pores of the porous template. The pores serve as negative recesses of the fine structure elements to be formed. The maximum average thickness of the fine structure elements is defined by the average pore diameter of the pores of the porous template. The maximum average length of the fine structure elements is defined by the average thickness a of the porous template, the propagation of the average thickness a of the porous template being substantially parallel to the length course of the pores of the porous template. The introduction of the material can be active or passive. By passive introduction of the material is meant that the material is applied to the porous template, and the introduction, more precisely the penetration of the material into the pores of the porous template by taking advantage of Gravity, done by capillary forces or gravity and capillary forces.

Active incorporation of material is understood to mean that the material is applied to the porous backing and the introduction, more specifically the penetration, of the material into the pores of the porous backing is actively assisted by, for example, spreading the material over a first surface is carried out substantially perpendicular to the propagation of the thickness a of the porous template, and on this first surface comprising the material, a pressure is exerted, the effective direction substantially parallel to the propagation of the thickness a of the porous template, and thus in the Western parallel to the course of the pores within the porous template, is created.

Preferably, in addition to a second surface, which is arranged substantially parallel to the first surface of this at a distance substantially corresponding to the magnitude of the thickness a, a vacuum applied, the effective direction arranged substantially parallel to the effective direction of the applied pressure is. It goes without saying that when the material is actively introduced, the forces acting on the passive introduction of the material can continue to act.

The active introduction of the material preferably supports and / or enhances the effect of the forces which act on the passive introduction of the material.

The simultaneous application of pressure and vacuum is preferred, but it is also preferred to apply only pressure or only vacuum, or to apply pressure and vacuum alternately. It is also understood, although not expressly stated above, that when the material is actively introduced into the pores of the porous receiver, it should be in a container having means to ensure the application and / or maintenance of pressure and / or vacuum to be able to.

Preferably, at least one first material is introduced substantially completely, but at least partially into the pores, and at least one second material is applied at least partially on preferably one surface of the porous template, which is preferably at least partially perpendicular to the length of the pores of the porous template , and materially connected to the at least first material which is located in the pores. The at least first material and the at least second material may be identical or different from each other.

After the active or passive application and / or introduction of the material on the porous template, a solidification step can follow.

The solidification step is to be understood as meaning that measures are carried out which solidify the material which at least partially comprises the fine structure elements or the at least one layer and the fine structure elements. The solidification can be done for example by evaporation of solvent, at least partially drying, pressing the material or a polymerization of the material.

Preferably, the solidification of the material is carried out so far that the fine structure elements or the at least one layer and the fine structure elements are formed, which is preferably in a subsequent separation step as completely destructively separate from the porous template. The separation can be effected by subtracting the fine structure elements or the at least one layer and the fine structure elements of the porous template. This has the advantage that in this case also the porous template can be separated substantially non-destructive from the fine structure elements or the at least one layer and the fine structure elements to after a possible cleaning step, for re-applying material for forming fine structure elements or the at least one layer and the fine structure elements for use can be provided in electrochemical cells.

But it is also possible that the porous template is not destructively separated from the fine structure elements or the at least one layer and the fine structure elements. This can be done, for example, by heating the porous template to or above a temperature (which may be the boiling or melting temperature of the material of the porous template), and thus liquefying or vaporizing the porous template. It is important to ensure that the temperature is lower than the melting temperature or boiling point or sublimation of the material which have at least partially the fine structure elements or the at least one layer and the fine structure elements. Another way to non-destructively separate the porous template from the fine structure elements or at least one layer and the fine structure elements, it is the porous template chemically (for example, by solvents or reagents which react with the material of the master layer and decompose this) or physically (for example Radiation or evaporation), whereby the molecular structure of the material constituting the porous template is dissolved.

In a preferred embodiment, an electrochemical cell according to the invention comprises at least one positive electrode, one negative electrode and at least one separator which separates the positive from the negative electrode, at least one electrode at least one Layer having active material and at least one substrate, wherein at least partially fine structure elements are arranged between the one layer with active material and the at least one substrate. separator

In one embodiment, a separator is used which separates the positive electrode from the negative electrode and is not or only poorly electron-conducting, and which consists of an at least partially permeable carrier. The support is preferably coated on at least one side with an inorganic material. As at least partially permeable carrier is preferably an organic material is used, which is preferably designed as a non-woven fabric. The organic material, which preferably comprises a polymer, and more preferably one or more polymers selected from polyethylene terephthalate (PET), polyolefin or polyetherimide, is coated with an inorganic, preferably ion-conducting material, which is more preferably in a temperature range of -40 ° C is at least 200 ° C ion conducting, and preferably at least one compound selected from the group of oxides, phosphates, silicates, titanates, sulfates, aluminosilicates with at least one of zirconium, aluminum, lithium and more preferably zirconium oxide.

The inorganic, ion-conducting material of the separator preferably comprises particles having a size diameter below 100 nm, preferably from 0.5 to 7 μm, preferably from 1 to 5 μm, preferably from 1.5 to 3 μm.

In one embodiment, the separator has a porous inorganic coating located on and in the nonwoven, the aluminum oxide particles having an average particle size of from 0.5 to 7 μm, preferably from 1 to 5 μm, and very particularly preferably from 1.5 to 3 μιη which are bonded with an oxide of the 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. Preferably, the maximum particle size is preferably 1/3 to 1/5 and more preferably less than or equal to 1/10 of the thickness of the nonwoven fabric used.

Suitable polyolefins are preferably polyethylene, polypropylene or polymethylpentene. Particularly preferred is polypropylene. The use of polyamides, polyacrylonitriles, polycarbonates, polysulfones, polyethersulfones, polyvinylidene fluorides, polystyrenes as organic carrier material is also conceivable. It is also possible to use mixtures of the polymers.

A separator with PET as carrier material is commercially available under the name Separion ^® . It can be prepared by methods as disclosed in EP 1 017 476.

The term "nonwoven web" means that the polymers are in the form of nonwoven fibers (non-woven fabric). Such nonwovens are known from the prior art and / or can be prepared by the known methods, for example by a spunbonding process or a meltblowing process, as described, for example, in DE 95 01 271 A1.

The separator preferably has a nonwoven which has an average thickness of 5 to 30 μm, preferably 10 to 20 μm. Preferably, the fleece is flexible. Preferably, the nonwoven fabric has a homogeneous pore radius distribution, preferably at least 50% of the pores have a pore radius of 75 to 100 pm. Preferably, the web has a porosity of 50%, preferably from 50 to 97%.

"Porosity" is defined as the volume of the web (100%) minus the volume of the fibers of the web (corresponds to the fraction of the volume of the web which 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 web also allows for a higher porosity of the separator, which is why a higher uptake of electrolytes with the separator can be achieved.

In a further embodiment, the separator consists of a polyethylene glycol terephthalate, a polyolefin, a polyetherimide, a polyamide, a polyacrylonitrile, a polycarbonate, a polysulfone, a polyethersulfone, a polyvinylidene fluoride, a polystyrene, or mixtures thereof. 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 pm. The polymers are preferably in the form of fiber webs, wherein the polymer fibers preferably have an average diameter of 0.1 to 10 pm, preferably from 1 to 4 pm.

The term "mixture" or "mixture" of the polymers means that the polymers are preferably in the form of their nonwovens, which are bonded together in layers. Such nonwovens or nonwoven composites are disclosed, for example, in EP 1 852 926.

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 methods of making the separators are disclosed in EP 1 783 852. 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% by weight of the magnesium oxide can be constituted 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. Preferably, the separators of this embodiment have a layer thickness of 4 to 25 pm.

Electrolyte As the electrolyte, a non-aqueous electrolyte consisting of an organic solvent and a lithium ion-containing, inorganic or organic salt can be used.

Preferably, the organic solvent is selected from ethylene carbonate, propylene carbonate, diethyl carbonate, dipropyl carbonate, 1, 2-dimethoxyethane, γ-butyrolactone, tetrahydrofuran, 2-methyltetrahydrofuran,, 3-dioxane, sulfulane, acetonitrile or phosphoric acid esters, or mixtures of these solvents. Preferably, the lithium ion-containing salt, 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 -], CF ₃ S0 ₃ -, C ₄ F _e S0 ₃ ^- [(CF ₃ S0 ₂ ) ₂ N] [(C ₂ F ₅ S0 ₂ ) N] ^" [(CN) ₂ N] -, CIO ₄ - Preferably, the separator of the electrochemical cell is impregnated with the electrolyte In one embodiment, the separator is impregnated with an electrolyte, which is configured as an ionic liquid Electrolyte include excipients 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.

Additives, such as phenylene carbonate, which can influence the formation of the solid electrolytes interface (SEI) layer on the electrodes are also usable. [Erfindung Die] The present invention also relates to a method for producing the electrochemical cell according to the invention, comprising the following steps:

Providing at least one positive electrode. Providing at least one negative electrode

Providing an intermediate layer which is arranged between the positive electrode and the negative electrode

• Assembly of the electrochemical cell according to the sequence of positive electrode / intermediate layer / negative electrode, wherein at least one electrode at least partially at least one layer having active material and at least one substrate, wherein disposed between the at least one layer with active material and the at least one substrate at least partially fine structure elements are.

As an intermediate layer may serve a separator or a polymer electrolyte. The separator is impregnated with electrolyte and built into the electrochemical cell.

The electrochemical cell of the present invention can be used to power mobile information equipment, tools, electric powered automobiles, and hybrid drive automobiles. Fig. 1 shows schematically the structure of an embodiment of an electrode according to the invention and also an embodiment of the method according to the invention for their assembly;

Fig. 2 shows schematically the structure of an embodiment of an electrode according to the invention in comparison to a prior art electrode. FIG. 1 shows an electrode 180 according to the invention consisting of a substrate 170, a layer 150 and fine structure elements 140 arranged between layer 150 and substrate 170. Due to the elastic configuration of the fine structure elements 140, the fine structure elements 140 can adapt to the surface structure of the substrate 170. This has the advantage of increasing the contact area between the substrate 70 and the layer 150, whereby a higher adhesiveness of the layer 150 on the metallic substrate 170 is achieved.

Furthermore, FIG. 1 shows a method for assembling an electrode 180 according to the invention.

In a first step, a porous template 100 having a thickness a, comprising a material 110 penetrated by pores 120, is provided. In a second step, a first material or a first material mixture 130 is applied to a surface having the openings of the pores 120 of the porous template 100.

In a third step, pressure is applied to the surface to which the first material or the first material mixture 130 has been applied. However, it can also be arranged on a second surface which is substantially parallel to the surface on which the first material or the first Applied to material mixture 130 was a vacuum applied. Furthermore, the second surface has outlet opening of the pores 120. The application of pressure to a first surface and the application of vacuum to a second surface may preferably be performed simultaneously, or alternately. But it can also be applied only pressure or only vacuum created. It is thereby achieved that the first material or the first material mixture 130 at least partially, preferably completely penetrates into the pores 120, and thus the fine structure elements 140 substantially comprising the first material or the first material mixture 130, are formed.

In a fourth pass, a second material or mixture of materials 150 is applied to a surface of the porous receiver 100 having openings of the pores 120 to form a layer. As a result, the layer comprising the second material or the second material mixture 150 is preferably connected to the fine material elements 140 in the pores 120 comprising the first material or the first material mixture 130, preferably connected in a materially bonded manner. The first material or the first material mixture 130 may be identical or different to the second material or the second material mixture 150. Preferably, the first material or the first material mixture 130 comprises substantially binder, preferably PVdF, and the second material or the second material mixture 150 has a mixture of binder, preferably PVdF, electrochemical active material and, optionally, other additives such as conductivity additives.

In a fifth step, the layer comprising the second material or the second material mixture 150, which is now connected to the fine structure elements 140, preferably cohesively, is separated from the porous template 100, preferably separated nondestructively. This can, as shown here, by the application of separation forces F _a and F _b to the porous template 100 and / or on the layer having the second material or the second material mixture 150 which is now connected to the fine structure elements 140 preferably cohesively done. In a sixth step, the layer 160 and the fine structure elements 140 may now be brought into contact with a substrate, preferably a metallic substrate 170, whereby the electrode 180 according to the invention comprising a layer 160 and a substrate 170 and between layer 160 and substrate 170 is arranged Fine structure elements 140, receives.

FIG. 2 shows an electrode 210 according to the invention consisting of a substrate 213 and a layer 211 and fine structure elements 212 arranged between substrate 213 and layer 211. Due to the elastic configuration of the fine structure elements 212, the fine structure elements 212 can adapt to the surface structure of the substrate 213. This has the advantage that thereby the contact area between the substrate 213 and the layer 21 1 is increased, whereby a higher adhesiveness of the layer 21 1 is achieved on the substrate 213. The electrode 210 according to the invention can be produced, for example, by the method illustrated in FIG.

In comparison to the electrode 210 according to the invention, a prior art electrode 220 consists of a layer 221 and a substrate 222 between layer 221 and substrate 222 arranged fine structure elements. Due to the lack of fine structure elements, the layer 221 has a smaller contact area with the substrate 222.

Claims

claims

An electrochemical cell comprising at least one negative electrode and at least one positive electrode, wherein at least one

Electrode at least one substrate and at least one layer having active material, characterized in that at least partially fine structure elements are arranged between this layer with active material and the substrate.

Electrochemical cell according to claim 1, characterized in that the at least one layer of active material at least partially by means of the fine structure elements with the at least one substrate is at least partially connected so that the at least one layer is substantially non-destructive of the at least one substrate detachable.

Electrochemical cell according to at least one of the preceding claims, characterized in that the at least one layer is at least partially connected to the fine structure elements so that the fine structure elements are substantially non-destructive of the at least one layer detachable.

Electrochemical cell according to at least one of the preceding claims, characterized in that the at least one layer of active material at least partially by means of

Fine structure elements a reduced, preferably none

Volume change during loading and / or unloading processes undergoes. Electrochemical cell according to at least one of the preceding claims, characterized in that the at least one

Layer of active material at least partially comprises materials used in an electrochemical cell,

preferably selected from polymeric materials, materials comprising polymeric precursors (for example monomers),

electrochemical active material, separator materials,

Conductivity additives, liquid or gel materials, metallic materials or mixtures thereof.

Electrochemical cell according to at least one of the preceding claims, characterized in that the fine structure elements comprise at least one material which substantially

is different from the active material, and / or which is substantially different from the binder used for active materials.

Electrochemical cell according to at least one of the preceding claims, characterized in that the fine structure elements or the at least one layer and the fine structure elements

be formed by using a porous template or a template layer having negative recesses of

Fine structure elements.

Electrochemical cell according to at least one of the preceding claims, characterized in that the negative electrode at least partially comprises an electrochemical active material 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. Electrochemical cell according to at least one of the preceding claims, characterized in that the positive electrode at least partially comprises at least one electrochemical active material which is selected from: a. at least one compound L1MPO4, 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.

A process for producing an electrochemical cell according to any one of the preceding claims, comprising the following steps.

• Provide at least one positive electrode

• Provide at least one negative electrode

Assembly of the electrochemical cell according to the sequence of positive electrode / intermediate layer / negative electrode, characterized in that at least one electrode at least partially at least one layer having active material and at least one substrate, wherein between the at least one layer and the at least one substrate at least partially fine structure elements are arranged.

Use of the electrochemical cell according to one of claims 1 to 9 for supplying energy to a consumer, in particular in mobile information devices, tools, electrically powered automobiles or automobiles with hybrid drive.