Method for manufacturing an electrode, electrode, and energy storage device comprising the electrode

Abstract

The invention relates to a method for manufacturing an electrode for an energy storage device, comprising the following process steps: A) Providing a first electrode film that is self-supporting and electrically conductive and a second electrode film that is self-supporting and electrically conductive, B) Providing at least one current collector flag, wherein the current collector flag is electrically conductively connected to movable wires, and C) Arranging the movable wires of the current collector flag between the first and second electrode films, and connecting the first electrode film to the second electrode film to form a self-supporting electrode layer, whereby the electrode is formed and the current collector flag protrudes from the electrode layer and the movable wires extend into the electrode layer. Such a method is particularly suitable for producing electrodes in which there are no mechanical stresses between a current collector and the electrode layer.

Description

[0001] The present invention relates to a method for producing an electrode for an energy storage device, the electrode, and an energy storage device comprising the electrode.

[0002] In the production of electrodes for energy storage devices, such as lithium-ion or solid-state batteries, electrode materials are often applied to current collector foils in a wet-chemical process using doctor blades or slot dies, and then dried to form an electrode layer. Drying is often very time-consuming, and defects in the electrode composite layer, such as air inclusions, can occur during the wet-chemical application process. Furthermore, poor adhesion of the electrode layer to the current collector foil is also a problem.

[0003] The production of dry electrode layers as electrode foils is also known. These can be applied to a current collector foil or a current collector mesh by calendering. During calendering, the current collector foil can be deformed, resulting in internal mechanical stresses building up between the electrode foil and the current collector foil. To ensure sufficient adhesion of the electrode foils to the current collector foil, the current collector foils must often be etched or pretreated with primers in a time-consuming and costly process. The current collector foils, which are usually made of copper in the case of anode foils and frequently of aluminum in the case of cathode foils, also increase the weight and cost of the individual electrodes.

[0004] The object of the present invention is to provide a method for producing an electrode that is improved with respect to the above-mentioned disadvantages. In particular, the object of the present invention is to provide a method for producing an electrode in which the internal mechanical stress between the current-discharging structures and the electrode material is reduced.

[0005] This problem is solved by a method for producing an electrode for an energy storage device. An electrode and an energy storage device are the subject of further independent patent claims.

[0006] One aspect of the invention provides a method for producing an electrode for an energy storage device. The method comprises the following steps: A) Providing a first electrode film which is self-supporting and electrically conductive and a second electrode film which is self-supporting and electrically conductive, B) Providing at least one current collector lug, wherein the current collector lug is electrically conductively connected to movable wires and C) Arranging the movable wires of the current collector tab between the first and second electrode films, and connecting the first electrode film to the second electrode film to form a self-supporting electrode layer, wherein the electrode is formed and wherein the current collector tab protrudes from the electrode layer and the movable wires extend in the electrode layer.

[0007] The method according to the invention allows for a simple connection of self-supporting electrode films to form an electrode layer, wherein movable wires are used as structures for conducting the electrical current, which are electrically conductively connected to at least one current collector tab. The movable wires can be arranged particularly easily between the first and second electrode films. Due to the mobility of the wires, mechanical stresses can be avoided during the connection of the electrode films, which often occur with flat current collector foils. Rather, the movable wires also adapt particularly easily to possible unevenness of the electrode films, thus preventing buckling, which can occur due to mechanical stresses between a current collector and the electrode layer.Furthermore, in the method according to the invention, a first and a second electrode film are bonded together, thus avoiding the problems of poor adhesion that typically occur when bonding electrode films to metallic current collector foils. This also reduces any tension that may occur between the current conductor foil and the electrode foil, which can lead to a saber-like bending of the electrode. In particular, the method according to the invention eliminates the need for etching the electrical wires or pretreating them with a primer.

[0008] During operation of the electrode, the current is conducted through the electrode material to the current collector tab via the electrically conductive wires, and from there to the electrical pole of the energy storage device connected to the current collector tab. During the bonding of the first and second electrode films, the movable wires are fixed in different positions in the forming electrode layer and extend randomly from the current collector tab within the electrode layer.

[0009] The wires extending in a random manner within the electrode layer can meander through the electrode layer in various ways, with different wires usually meandering in different ways within the electrode layer.

[0010] The movable wires are also flexible and can, for example, be bent prior to joining the first electrode film and the second electrode film so that, after fixing in process step C), they extend primarily away from the current collector tab through the formation of the self-supporting electrode layer. Due to slight differences in the surface properties of the two electrode films, the movable wires are nevertheless fixed in different positions in the forming electrode layer during process step C).

[0011] The first self-supporting electrode film and the second electrode film may comprise a binder that can be used to bond both electrode films. The first and second electrode films can be used as rolls and unrolled during process step A).

[0012] In a further embodiment of a method according to the invention, a plurality of current collector tabs can be provided in method step B). Each current collector tab is connected to movable wires. In method step C), the movable wires of the plurality of current collector tabs are then arranged between the first and second electrode films, with the plurality of current collector tabs protruding from the electrode layer.

[0013] After the two electrode films are bonded, the wires of the numerous current collector tabs run within the electrode layer. Using this process, so-called "multi-tab" electrodes, which have a large number of current collector tabs, can be produced particularly easily. Such electrodes with a large number of current collector tabs can reduce the ohmic resistance of the electrode layer.

[0014] In method step C), an electrode layer can be formed that has a first edge and a second edge opposite the first edge. The at least one current collector tab or the plurality of current collector tabs can protrude from the electrode layer at the first edge. The wires fixed in the electrode layer, which are electrically conductively connected to the one or the plurality of current collector tabs, can extend randomly from the current collector tabs toward the second edge within the electrode layer.

[0015] This can particularly easily ensure the current conduction through the electrode from the second edge in the direction of the current collector lug located at the first edge or in the direction of the plurality of current collector lugs.

[0016] The electrode formed by a method according to the invention can, in particular, form a long strip comprising a strip-shaped electrode layer. The long strip is normally rolled up into an electrode roll. The electrode roll can have a length of up to 1000 meters, in particular a length of 500 meters to 1000 meters. The electrode roll can be cut into individual electrode sections, which are incorporated as electrodes in energy storage devices. The individual electrode sections can have a length of 4 to 5 meters, for example for the 4695 round cell format. These are cylindrical cells with a diameter of 46 mm and a height of 95 mm. The first and second edges of the electrode layer preferably extend along the main axis of the strip-shaped electrode layer. In particular, the first and second edges of the electrode layer can form the long edges of the strip-shaped electrode layer.

[0017] In a further embodiment of a method according to the invention, a current collector lug or a plurality of current collector lugs can be provided in method step B), wherein the current collector lug or the current collector lugs are connected to individual, unconnected wires and wherein the wires are movable relative to one another.

[0018] These isolated, unconnected wires are movable relative to each other and make it particularly easy to connect the first and second electrode films without causing mechanical stress between the wires and the electrode layer being formed.

[0019] Furthermore, it is possible for some of the movable wires connected to a current collector tab to be interconnected by cross-connections. This can also enable current flow between interconnected movable wires in the surface of the electrode material. The cross-connections can, for example, comprise electrical wires connected to two movable wires. The cross-connections can, in particular, run transversely to the extension direction of the wires toward the second edge in the electrode layer being formed.

[0020] In method step B), a current collector lug or a plurality of current collector lugs can be provided, wherein the movable wires of the current collector lug or the current collector lugs comprise wires which are electrically conductively connected to the current collector lug separately from one another.

[0021] Such movable wires are not connected to each other, but are only electrically connected to the respective current conductor lug. This makes it particularly easy to keep the wires movable relative to each other.

[0022] In process step A), a first and a second electrode film can be provided, comprising components selected from a group consisting of: electrically conductive additives, electrically conductive polymers, and at least one dry binder. The electrically conductive additives can be selected from a group consisting of: carbon powder, graphite, carbon nanotubes (CNTs), carbon nanoparticles, and metal particles. Carbon nanotubes and / or carbon nanoparticles are preferably used as electrically conductive additives. The dry binder can be selected from a group consisting of: polytetrafluoroethylene, ultra-high molecular weight polypropylene, polyethylene, copolymers, polymer blends, and the like. These dry binders are fibrillatable, in particular dry fibrillatable without the addition of process solvents.The dry binders can be mixed or fibrillated, particularly with high shear force, for example, using a jet mill, a pin mill, an impact pulverizer, or a mixer. The carbon powder can comprise carbon selected from a group consisting of: carbon particles impregnated with metals, graphite particles, and carbon black particles.

[0023] The electrically conductive polymers may, for example, include poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS).

[0024] The first and second electrode films can, in particular, comprise 80 to 95 weight percent of active material, 0 to 10 weight percent of conductive carbon, for example, carbon black, carbon nanotubes (CNTs), carbon nanoparticles, graphite, and 3 to 15 weight percent of dry binder. The weight percentages in each case refer to the total weight of the electrode films.

[0025] The active material comprises, in particular, electrochemically active material capable of absorbing and releasing metal ions, in particular lithium ions. The first and second electrode films can comprise, for example, graphite as the active material if the electrode film is to be used as an anode in a lithium-ion battery. Lithium ions can intercalate in the graphite. Oxides comprising lithium, nickel, manganese, and cobalt, or phosphates, such as LiCoO2, LiNi, are used as the active material for the cathode in a lithium-ion battery as an energy storage device. 0,33 CO 0,33 Mn 0,33 O2 and / or LiFePO4. Nickel-rich Mn-Co oxides (NMC) are typically used for high-energy cells. Silicon, silicon-carbon compounds, and / or silicon oxides that can absorb lithium ions can also be used as the active material.

[0026] The electrically conductive self-supporting electrode films can be produced, for example, by calendering mixtures of the respective components.

[0027] In a further embodiment of a preferred method according to the invention, a first and a second electrode film are provided in process step A), which are self-supporting electrode dry films. The self-supporting electrode dry films can be produced using a solvent-free process, as described above, by means of extrusion and calendering. The self-supporting electrode dry films can, in particular, be free of process solvent residues. In wet-chemical processes for producing electrodes, solvents such as water or N-methyl-2-pyrrolidone are normally used. Self-supporting electrode dry films are described, for example, in US 2013 / 157141 A1, which is hereby incorporated by reference in its entirety.

[0028] Such a process is particularly well suited to provide self-supporting electrically conductive electrode films that can be connected to the flexible wires using the current collector tabs.

[0029] In process step B), one or more strip-shaped current collector tabs can be provided. Strip-shaped current collector tabs are particularly well suited for connection to the terminals of an energy storage device.

[0030] The current collector lug or the plurality of current collector lugs may comprise or be made of a metal or a metal alloy. In particular, the current collector lugs may comprise metals and alloys selected from a group consisting of: copper, aluminum, copper-aluminum alloy, nickel, stainless steel, titanium, silver, and an aluminum-cadmium alloy.

[0031] Depending on the design of the energy storage device, the flat current collector tabs can have a width of 0.5 cm to 1 cm and / or a length of 0.7 cm to 1.3 cm.

[0032] The movable wires may comprise or be made of a metal or metal alloy, wherein the metal or metal alloy is selected from a group consisting of: copper, aluminum, nickel, and copper alloys. Movable wires for the anode preferably comprise or are made of copper. Movable wires for the cathode preferably comprise or are made of aluminum.

[0033] The movable wires can have a round or square cross-section. In particular, the wires can have a thickness of 0.1 mm to 1 mm and / or a length of 1 cm to 10 cm.

[0034] In particular, movable electrical wires of different thicknesses and / or lengths can be used in the manufacture of an electrode for an energy storage device. Thicker electrical wires enable better conduction of current and heat to the current collector tab, while thinner wires reduce the weight of the electrodes.

[0035] In process step B), one current collector lug or a plurality of current collector lugs can be provided, each current collector lug being connected to a plurality of movable wires. In particular, each current collector lug can be connected to at least two, more preferably at least three, movable wires. A current collector lug can be connected to 2 to 5, preferably 3 to 4, movable electrical wires. This ensures sufficient electrical conductivity from the electrode layer to the current collector lugs.

[0036] The movable wires can be electrically connected to a current collector lug, in particular by soldering, gluing or welding.

[0037] In process step C), the first electrode film can be bonded to the second electrode film using a process parameter selected from the group consisting of: application of pressure elevated relative to normal pressure, and application of temperatures elevated relative to room temperature. Preferably, in process step C), the first electrode film can be bonded to the second electrode film by calendering. For this purpose, the first electrode film and the second electrode film can be passed through rotating rollers, whereby both electrode films are bonded to one another by means of pressure and elevated temperature.

[0038] In process step C), a linear load of 100 N / mm to 3000 N / mm can be applied. For example, a linear load of 330 N / mm can be applied on a 14-roll calender.

[0039] In process step C), a temperature of 50°C to 280°C, preferably a temperature of 80°C to 250°C, can be used.

[0040] In process step C), in particular, the first electrode film can be directly connected to the second electrode film. Connecting two electrode films to each other is easier to accomplish than the prior art connection of an electrode layer to a flat current collector foil or a current collector network. In particular, the first electrode film and the second electrode film can be directly connected to each other in the spaces between adjacent electrical wires.

[0041] In the method according to the invention, no current collector layer or current collector network needs to be arranged between the first electrode film and the second electrode film.

[0042] The present invention also relates to an electrode for an energy storage device. The electrode comprises: - a self-supporting dry electrode layer comprising active material, electrically conductive additives and a dry binder, wherein the dry electrode layer has a first edge and a second edge opposite the first edge, - at least one current collector lug, wherein the current collector lug is electrically connected to metallic and electrically conductive wires, and - wherein the current collector tab protrudes from the electrode layer at the first edge, and the electrical wires extend randomly in the dry electrode layer towards the second edge.

[0043] Such an electrode is particularly easy to manufacture because no complex pretreatment steps, such as etching a current collector foil, are necessary to ensure sufficient adhesion of the current collector foil to an electrode layer. Furthermore, such an electrode can exhibit increased long-term stability because delamination between the electrical wires and the dry electrode layer is not expected.

[0044] The electrode according to the invention can be either an electrode roll with a length of up to 1000 m or an already separated electrode that can be installed in an energy storage cell.

[0045] Various electrical wires extend in various random ways toward the second edge of the dry electrode layer. This distinguishes an electrode according to the invention from, for example, conventional electrodes with a current collector network in which various wires cross over in an orderly manner.

[0046] In a further embodiment of an electrode of the present invention, a plurality of current collector tabs are provided, each current collector tab being electrically connected to the metallic and electrically conductive wires. The plurality of current collector tabs can protrude from the electrode layer at the first edge. The electrically conductive wires can extend randomly in the dry electrode layer toward the second edge of the electrode layer.

[0047] Such an embodiment of an electrode according to the invention provides a “multi-tab” electrode in which the current can be discharged to the pole of the energy storage device via a plurality of current collector tabs.

[0048] In particular, with the plurality of current collector tabs, each current collector tab can be electrically connected to different electrical wires. These different electrical wires extend in a random manner toward the second edge of the electrode track and can ensure a good electrical connection between the electrode layer and the respective current collector tabs.

[0049] Electrically conductive wires that are electrically connected to adjacent current collector tabs can intersect in the dry electrode layer. This can ensure good electrical conductivity across the entire surface of the electrode layer and allow the current to be diverted to the current collector tabs. Furthermore, electrically conductive wires that are electrically connected to adjacent current collector tabs can contact each other. This can ensure particularly good electrical conductivity of the electrode layer across the entire surface, even between adjacent current collector tabs.

[0050] The electrical wires of a current conductor lug may comprise individual, unconnected wires. Such wires are particularly easy to move relative to other wires.

[0051] The electrical wires may comprise wires that meander toward the second edge of the dry electrode layer. It is possible for different electrical wires to meander in different, random ways toward the second edge of the dry electrode layer. The flexibility and mobility of the electrical wires during process step C), the bonding of the first electrode film to the second electrode film, ensures that no mechanical stresses arise between the wires and the forming electrode layer.

[0052] The metallic wires extending in the dry electrode layer may comprise wires of different lengths and / or different cross-sections.

[0053] The dry electrode layer can have a density of more than 0.3 g / cm 3 preferably more than 0.5 g / cm 3A dry electrode layer with such a density is particularly well suited as a self-supporting electrode layer. After bonding the first electrode film to the second electrode film by means of, for example, calendering, the dry electrode layer can have a density of 1.3 g / cm 3 up to 1.7 g / cm 3 for the anode and 3 g / cm 3 up to 3.6 g / cm 3 for the cathode.

[0054] The current collector lug(s) can be metal strips that are electrically connected to the electrical wires. These metal strips or current collector lugs can be easily connected to the terminal of an energy storage device, for example, by welding.

[0055] Each current collector lug can be electrically connected to a plurality of wires. The plurality of wires can be electrically connected to the current collector lug separately from one another. In particular, each of the wires of the plurality of wires can only be electrically connected to the current collector lug, with no further connections between different wires. This can ensure that the movable wires can move particularly easily relative to one another during process step C).

[0056] The electrically conductive wires can comprise or be made of metal and / or a metal alloy. Particularly preferably, the metal can be selected from a group consisting of copper, aluminum, and nickel. The metal alloy can be selected from a group consisting of Cu-Al and Ni-Cu.

[0057] The dry electrode layer of the electrode may comprise a dry binder selected from a group consisting of: polytetrafluoroethylene, ultra-high molecular weight polypropylene, polyethylene, copolymers, polymer blends, and the like.

[0058] The present invention furthermore also relates to an energy storage device comprising: - an electrode as described above, - a counter electrode, - a separator located between the electrode and counter electrode, and - an electrolyte.

[0059] The energy storage device can be, for example, a lithium-ion battery or a solid-state battery.

[0060] In a lithium-ion battery, an electrode according to the invention can be an anode and / or a cathode. The separator prevents an electrical short circuit between the electrode and the counter electrode and can be a porous, electrically insulating layer made of polyethylene or propylene, glass fibers, a polyolefin membrane, or another porous, electrically insulating material. In particular, an electrolyte solution containing an aprotic solvent such as ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, or 1,2-dimethoxyethane and a conducting salt, for example lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), or lithium bis(oxalato)borate, dissolved in the aprotic solvent, can be used as the electrolyte.

[0061] An electrode according to the invention can also be used in a solid-state battery. In such an energy storage device, lithium can be used as the anode, and an electrode according to the invention can be used as the cathode. A ceramic permeable to lithium ions, such as lithium orthosilicate, or glass can be used as the solid-state electrolyte.

[0062] Such energy storage devices can exhibit greater long-term stability due to the use of electrodes according to the invention, since delamination of the electrode layer from a current collector is not a concern. The possibility of current dissipation across the surface of the electrode via multiple current collector tabs contributes significantly to reducing the cell's internal resistance. Furthermore, the homogeneously distributed electrical dissipation also promotes the absence of "hot spots," excessive heating at localized points. Furthermore, such energy storage devices can be manufactured more cost-effectively and simply thanks to the electrode according to the invention.

[0063] In the following, aspects of the present invention will be explained in more detail with reference to figures and exemplary embodiments. They show: Fig. 1 a schematic cross-sectional drawing of a method according to the invention, Fig. 2 a schematic plan view of an electrode according to the invention, Fig. 3A and Fig. 3B is a schematic plan view and a cross-section through an embodiment of an electrode according to the invention, and Fig. 4A and Fig. 4B schematic drawings of a current collector lug, with metallic wires connected thereto, with movable, flexible wires with cross connections, as well as a schematic plan view of an embodiment of an electrode according to the invention with these current collector lugs.

[0064] Fig. Figure 1 shows a schematic cross-sectional drawing of a method according to the invention, in which a first self-supporting electrically conductive electrode film 2A is extruded from a first extruder 7A and a second self-supporting electrically conductive electrode film 2B is extruded from a second extruder 7B. Both electrode films 2A, 2B are pressed together by means of calendering rollers 6A, 6B under pressure and at an elevated temperature, with current collector tabs 3, which are connected to movable electrical wires 4, being positioned between the two electrode films. In this case, the electrode 1 is formed with the self-supporting electrode layer 2C, from which the current collector tabs 3 protrude. An example is shown in the lower right corner of the Fig. 1 shows a plan view of a current collector lug 3 with the electrically conductive wires 4.

[0065] Fig. Figure 2 shows a schematic plan view of an embodiment of an electrode 1 according to the invention, wherein, for reasons of clarity, only the first electrode film 2A is shown, but not the second electrode film 2B located thereabove. This electrode according to the invention is already produced by singulation from an electrode roll and can be installed as a single electrode in an energy storage device. This second electrode film 2B would conceal the electrically conductive wires 4 extending through the electrode layer, which in the Fig. 2. Each current collector lug 3 is connected to a plurality of metallic wires 4, which extend randomly toward the second edge 2E of the electrode layer. Each electrically conductive wire 4 meanders in a different way toward the second edge 2E of the electrode layer. These electrically conductive wires can be positioned particularly easily between the two conductive electrode films without the risk of mechanical stresses occurring. The current collector lugs 3 protrude from the first edge 2D of the electrode film. Electrically conductive wires 4 of adjacent current collector lugs 3 can either cross or contact each other, as shown in the dashed region 8A. Furthermore, an intermediate region 8B, shown in dashed lines, in which no wires are present, can form between the electrical wires 4 of two adjacent current collector lugs 3.

[0066] Fig. 3A shows a plan view of an embodiment of an electrode 1 according to the invention with the self-supporting electrode layer 2C and the current collector lugs 3 protruding from the electrode layer. Fig. 3B shows a cross section through the electrode 1 according to the invention of the Fig. 3A along the dashed line marked 9. Fig. 3B shows how the electrically conductive wires 4 extend from the current collector tab 3 protruding at the first edge 2D through the self-supporting electrode layer 2C in the direction of the second edge 2E of the electrode layer.

[0067] Fig. Figure 4A schematically shows a top view of a current collector lug 3 connected to two different groups 4, 4' of electrically conductive wires. The groups 4, 4' of electrically conductive wires each consist of two electrically conductive wires that are electrically connected to each other by a cross-connection 4A.

[0068] Such electrically conductive wires can ensure good electrical conductivity between adjacent electrical wires. The different groups 4, 4' of electrically conductive wires are movable relative to each other. Fig. 4B shows a schematic plan view of an embodiment of an electrode 1 according to the invention, the current collector lugs 3, as in Fig. 4A. For reasons of clarity, only the first electrode film 2A is shown, so that the course of the electrical wires 4 within the electrode layer is visible. In addition, current collector tabs with electrical wires, as in Fig. 1 and Fig. 2 shown.

[0069] The invention is not limited by the description based on the exemplary embodiments. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the patent claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This 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

[0000] US 2013 / 157141 A1

[0027]

Claims

[1] Method for producing an electrode (1) for an energy storage device, comprising the method steps: A) providing a first electrode film (2A) which is self-supporting and electrically conductive, and a second electrode film (2B) which is self-supporting and electrically conductive, B) providing at least one current collector lug (3), wherein the current collector lug (3) is electrically conductively connected to movable wires (4), and C) Arranging the movable wires (4) of the current collector tab (3) between the first and second electrode films (2A, 2B), and connecting the first electrode film to the second electrode film to form a self-supporting electrode layer (2C), wherein the electrode (1) is formed and wherein the current collector tab (3) protrudes from the electrode layer and the movable wires (4) extend in the electrode layer (2C). [2] A method for producing an electrode according to the preceding claim, wherein in method step B) a plurality of current collector tabs (3) are provided, each current collector tab (3) being connected to movable wires (4), and wherein in method step C) the movable wires of the plurality of current collector tabs are arranged between the first and second electrode films and wherein the plurality of current collector tabs protrude from the electrode layer. [3] Method for producing an electrode according to one of the preceding claims, wherein in method step C) an electrode layer (2C) is formed which has a first edge (2D) and a second edge (2E) opposite the first edge, wherein the at least one current collector lug (3) or the plurality of current collector lugs protrude from the electrode layer at the first edge (2D) and wherein the movable wires (4) extend in the direction of the second edge (2E) within the electrode layer. [4] A method for producing an electrode according to one of the preceding claims, wherein in method step B) a current collector lug or a plurality of current collector lugs is provided, wherein the current collector lug or the current collector lugs are connected to individual, unconnected wires, wherein the wires are movable relative to one another. [5] A method for producing an electrode according to any one of the preceding claims, wherein in process step A) a first and a second electrode film are provided which are self-supporting electrode dry films, preferably wherein the self-supporting electrode dry films are free of process solvent residue. [6] A method for producing an electrode according to any one of the preceding claims, wherein in method step C) the first electrode film is directly connected to the second electrode film, preferably wherein no current collector layer or current collector network is arranged between the first electrode film and the second electrode film. [7] Electrode (1) for an energy storage device, comprising: - A self-supporting dry electrode layer (2C) comprising active material, electrically conductive additives and a dry binder, wherein the dry electrode layer has a first edge (2D) and a second edge (2E) opposite the first edge, - At least one current collector lug (3), wherein the current collector lug (3) is electrically connected to metallic and electrically conductive wires (4), - Wherein the current collector lug (3) protrudes from the electrode layer (2C) at the first edge (2D) and where the electrical wires (4) extend randomly in the dry electrode layer in the direction of the second edge (2E). [8] Electrode according to the preceding claim, wherein a plurality of current collector tabs are present, and each current collector tab is electrically conductively connected to electrical wires, and wherein the plurality of current collector tabs protrude from the electrode layer at the first edge and the electrically conductive wires extend randomly in the dry electrode layer towards the second edge [9] Electrode according to the preceding claim, wherein electrically conductive wires connected to adjacent current collector tabs cross in the dry electrode layer. [10] An electrode according to any one of the preceding claims 7 to 9, wherein the electrical wires of a current collector tab comprise isolated, unconnected wires. [11] An electrode according to any one of the preceding claims 7 to 10, wherein the metallic wires comprise wires that meander towards the second edge of the dry electrode layer. [12] Electrode according to one of the preceding claims 7 to 11, wherein the wires comprise or are made of metal and / or a metal alloy, preferably wherein the metal is selected from a group consisting of: copper, aluminum, nickel and wherein the metal alloy is selected from a group consisting of: Cu-Al, and Ni-Cu. [13] Electrode according to one of the preceding claims 7 to 12, wherein the dry electrode layer comprises a dry binder selected from a group consisting of: polytetrafluoroethylene, polyethylene, and polypropylene. [14] Energy storage, comprising an electrode according to one of the preceding claims 7 to 13, a counter electrode, a separator located between the electrode and counter electrode, and an electrolyte.

Images