Electrode arrangement and battery comprising the electrode arrangement

Abstract

The present invention provides an electrode arrangement, designed for arrangement in a battery, and a battery comprising such an electrode arrangement, wherein the electrode arrangement (1) has at least two layers (10, 20) each composed of an electrode pair having in each case an elongate anode surface element (11, 21) and an associated elongate cathode surface element (12, 22), which are arranged one above another in each case in a manner separated by a separator layer (13, 23), and at least one of the anode surface elements (11, 21) or cathode surface elements (12, 22) has a surface shape comprising perforations (14, 24), and wherein this at least one anode or cathode surface element (11, 21, 12, 22) differs from the second elongate associated anode or cathode surface element (11, 21, 12, 22) in regard to the surface shape thereof, wherein the electrode pair forms an asymmetrical electrode pair.

Description

[0001] ELECTRODE ASSEMBLY AND BATTERY WITH THE ELECTRODE ASSEMBLY

[0002] The invention relates to an electrode arrangement which is designed to be arranged in a battery and to a battery having such an electrode arrangement.

[0003] Lithium-ion batteries are known from the state of the art and are used, for example, in the automotive industry for electric / hybrid vehicles. Furthermore, batteries for stationary storage systems are needed for energy supply in various areas, which require energy storage systems with a long service life and energy and power densities that can be flexibly accessed depending on the requirements profile. However, currently, the performance and capacity of lithium-ion batteries cannot be increased simultaneously.

[0004] It is known to structure electrodes to create so-called 3D batteries, in which all electrodes are perforated at predetermined locations, thus increasing the battery's efficiency (e.g., the fast-charging capacity of an electric car). However, this type of structuring removes active material from the electrodes: A mass loss of the cathodes can be in the range of 10-20% of the total mass of the cathode and is therefore generally too high because a large amount of electrode material is removed to create perforations. This results in capacity losses. Other concepts aimed at increasing battery performance can only use electrodes with low areal capacity or thin electrode layers, which in turn means a decrease in the gravimetric and volumetric energy density.

[0005] Based on this prior art, it is an object of the present invention to provide an improved electrode arrangement in which power and capacity can be flexibly increased and which is suitable for being arranged in a battery.

[0006] This object is achieved by an electrode arrangement having the features of claim 1.

[0007] The further object of providing a battery with an improved electrode arrangement whose power and capacity can be flexibly increased is achieved by the battery having the features of independent claim 7. Further developments of the electrode arrangement and the battery are set forth in the respective subclaims.

[0008] According to a first embodiment of the electrode arrangement, which is designed for arrangement in a battery, the electrode arrangement has at least two layers, each comprising an electrode pair, each comprising an elongated anode surface element and an elongated cathode surface element. The anode surface element and the cathode surface element are each arranged one above the other, separated by a separator layer. According to the invention, at least one of the anode surface elements or the cathode surface elements has a surface shape with perforations. This at least one anode or cathode surface element differs from the second elongated associated anode or cathode surface element with regard to its surface shape, wherein the electrode pair forms an asymmetrical electrode pair.To achieve the highest possible energy density at the electrode level, the active mass loss due to perforations should be kept as low as possible. The cathode is the source of lithium ions for the energy storage process. Therefore, the concept of asymmetric electrodes is preferably applied to cathode surface elements.

[0009] “Arranged one above the other” here means arranged in layers like a sandwich, and also includes, for example, the vertical position in space if the electrode arrangement is positioned accordingly.

[0010] The asymmetric, one-sided structuring of the respective anode or cathode surface element with perforations makes it possible to reduce mass loss while simultaneously increasing capacity. The intermediate separator layer is an electrically insulating material, such as polyolefins (polyethylene PE, polypropylene PP), multilayer polyolefins (PE / PP or PP / PE / PP), ceramic-coated polyolefins (Al2O3 / PE), or so-called ceramic separators, whose carrier materials consist of polymer fleece.

[0011] "Surface element" refers here to any type of electrode that can be provided as an anode or cathode and that, in the geometric sense, extends flatly over a certain predetermined surface section. "Asymmetric electrode pair" refers here to an electrode pair consisting of an anode and a cathode, in which one of the partners, either the anode or the cathode, has openings, so that the surface shape of the anode surface element differs from the cathode surface element. Thus, the anode surface element of the electrode pair can have openings, whereas the cathode surface element has no openings, or vice versa.

[0012] According to a further embodiment of the electrode arrangement according to the invention, both layers provide an asymmetrical electrode pair of the electrode arrangement. Thus, an asymmetrical electrode pair can be present in each layer, or a layer can be symmetrically structured and both surface elements of the respective layer can have perforations.

[0013] In a particular embodiment, only the cathode (or anode) surface element of one of the at least two layers has openings, while the cathode (or anode) surface element of the at least one other layer has no structuring. Both layers can be designed symmetrically or asymmetrically.

[0014] According to a further embodiment of the electrode arrangement according to the invention, the surface elements of a layer of the at least two layers that does not provide the asymmetrical electrode pair of the electrode arrangement have surface shapes of congruent surface elements with perforations. This enables different cell designs.

[0015] According to yet another embodiment of the electrode arrangement according to the invention, the perforations are grooves, channels, blind holes or openings. Other structures are also possible, for example grids or a combination of perforations such as lines and blind holes. It is important that the perforations in the surface elements or electrodes are continuous over the electrode surface and thus have a different surface design compared to a simple flat electrode. The distance between the perforations is preferably in the range between 50 pm and 2000 pm, particularly preferably in the range from 80 pm to 600 pm. The depth of the perforations is preferably at least 10% of the electrode thickness, particularly preferably at least 50% of the electrode thickness, in particular at least 70% of the electrode thickness.In a particular embodiment, the structure is a line or lattice structure, preferably with a line spacing of 100 pm to 2000 pm, particularly preferably 100 pm to 600 pm. The channel width is between 10 pm and 100 pm, particularly preferably between 20 pm and 80 pm. A lattice describes two line structures rotated by any angle. An angle of 90° is preferred for a classic lattice.

[0016] In a further embodiment, the structure is a hole structure composed of hexagonally or cubically arranged holes, preferably with a hole spacing of 50 pm to 1000 pm, particularly preferably between 80 pm and 300 pm. The hole diameter is between 10 pm and 200 pm, preferably between 20 pm and 150 pm, particularly preferably between 30 pm and 100 pm.

[0017] Furthermore, a structural combination of holes and lines / gratings with structural spacings between 50 pm and 2000 pm, particularly preferably in the range from 80 pm to 600 pm, is provided.

[0018] According to yet another embodiment of the electrode arrangement according to the invention, the surface elements are thick-film electrodes. A predetermined layer thickness is in a range from 40 pm to 250 pm, preferably in a range from 100 pm to 200 pm, particularly preferably in a range of 150 pm. The use of thick-film electrodes results in an increased surface capacitance. The surface capacitances are in the range of 1-14 mAh / cm 2 , preferably in the range of 3-8 mAh / cm 2 . or 4 to 7mAh / cm 2 .

[0019] According to yet another embodiment of the electrode arrangement according to the invention, a current collector is located adjacent to each of the anode surface elements and the cathode surface elements. This allows the voltage that builds up between the electrodes to be tapped or the current to be diverted.

[0020] The invention further relates to a battery with an electrode arrangement according to the invention.

[0021] This battery is suitable for use in the field of secondary cells / accumulators (H01M 10 / 00), and particularly for lithium-ion batteries. Likewise for post-lithium batteries, sodium batteries, and solid-state batteries. The electrode arrangement according to the invention can also be used in batteries with large-area electrodes, e.g., pouch cells or prismatic cells. Preferred areas of application for the battery according to the invention are in the field of stationary energy storage and the automotive industry. The battery according to the invention, thanks to the electrode arrangement according to the invention, enables flexibly available energy and power densities; the concept of asymmetric electrode pairs can meet these requirements, with the available capacity for C rates greater than C / 5 (i.e., five hours for a complete discharge or charge of the battery) being significantly increased compared to the prior art.Battery life also increases, especially when using electrodes with high mass loading (> 20 mg / cm. 2 with layer thicknesses > 100 pm).

[0022] A combination of asymmetric electrode pairs and the use of thick-film electrodes thus enables a cost-effective and high-performance solution for lithium-ion batteries. The degradation behavior can also be improved compared to the state of the art.

[0023] A method for producing the electrode arrangement according to the invention may comprise the following steps:

[0024] - Providing a substrate for a predetermined battery design,

[0025] - applying at least two surface elements, an anode and a cathode surface element, as well as at least one separator layer and current collectors, one for each type of surface element (anode / cathode) to the substrate.

[0026] - Structuring at least one surface element, for which purpose electrode material is removed by laser ablation and perforations are introduced into the at least one surface element. Other structuring mechanisms can also be used, including in combination, e.g., embossing, printing, and milling. The depth of the perforations is preferably at least 10% of the electrode thickness, particularly preferably at least 50% of the electrode thickness, in particular at least 70% of the electrode thickness. In particular, the perforations extend to the current collector.

[0027] Multilayer electrode assemblies can then be produced, with two layers being created by folding, rolling, stacking, or double-sided coating. This allows the production of composite electrodes that can be manufactured in a particularly space-saving manner. Further embodiments of the electrode assembly and the battery, as well as some of the advantages associated with these and other embodiments, will become clear and easier to understand from the following detailed description with reference to the accompanying figures. Objects or parts thereof that are essentially the same or similar may be provided with the same reference numerals. The figures are merely a schematic representation of one embodiment of the invention.

[0028] Showing:

[0029] Fig. 1 is a sectional view of a first electrode arrangement according to the invention, and Fig. 2 is a sectional view of a further electrode arrangement according to the invention.

[0030] In Figs. 1 and 2, an electrode arrangement 1 is schematically shown. The electrode arrangement is constructed from two layers 10, 20, which appear to be spatially adjacent to one another in Figs. 1 and 2. Depending on their spatial positioning, this is also synonymously referred to here as "lying one above the other." Each layer 10, 20 has a pair of electrodes, with each pair of electrodes comprising flat, elongated electrodes in the form of surface elements. Each pair of electrodes has an elongated anode surface element 11, 21 and a corresponding cathode surface element 12, 22.

[0031] The anode surface elements 11, 21 and the cathode surface elements 12, 22 are separated by separator layers 13, 23, which electrically insulate the surface elements 11, 12, 21, 22 from one another. In layer 10, a current collector 15 is provided on the left in Fig. 1, adjacent to the anode surface element 11. In layer 20, a current collector 25 is provided on the right in Fig. 1, adjacent to the anode surface element 21. The cathode surface elements 12, 22 of layers 10, 20 are adjacent to one another in the center of the figurative representations in Figs. 1 and 2 and are separated by a common current collector 26.

[0032] In Fig. 1, the anode surface element 11 and the cathode surface element 22 have a total of five perforations 14, 24, which extend in a groove-like manner through the entire surface element to the respective current collector 15, 26. These two surface elements 11 and 22 have a different surface shape compared to the paired surface elements 12 and 21 and thus differ from the consistently flat surface elements 12 and 21. As a result, electrode pairs of different symmetries, i.e., asymmetrical electrode pairs, are formed in layer 10 and layer 20. The embodiment in Fig. 1 therefore shows two asymmetrical electrode pairs, whereas the embodiment in Fig. 2 shows an asymmetrical electrode pair in layer 10 and a symmetrical electrode pair in layer 20, since both surface elements, anode surface element 21 and cathode surface element 22, show five openings.

[0033] In contrast to the prior art, which previously used electrode layer thicknesses of 50 pm to 70 pm, the electrode arrangement according to the invention uses thick-film electrodes with a thickness of 150 pm each on both sides of the respective current collector. Increasing the layer thickness increases the surface capacity (per side) from approximately 2 to 3 mAh / cm 2 to values ​​of > 4 to 6 mAh / cm 2 By using laser ablation (e.g., with ultrashort pulse laser radiation), the perforations can be introduced into the double-sided coated composite electrodes as asymmetrically arranged electrode structures (channels, holes, blind holes, grids) extending to the current collector. Pouch cells with such asymmetric electrode structures exhibit higher capacity at C-rates > C / 5 and improved cycle stability compared to cells with unstructured, continuously flat surface elements or electrodes.

[0034] Electrode arrays using laser-ablated cathode surface elements, such as Li(NiO.6MnO.6COO.2)O2 (NMC 622), which have channel structures as perforations, exhibit higher specific capacitances compared to electrode arrays with unstructured cathodes, especially when thick-film electrodes with layer thicknesses greater than 100 pm are used at C rates greater than C / 5. Other structure types, such as freestanding or line structures or holes for NMC 811, LiM^C, and LiFePC (LFP) cathodes, are possible.

[0035] The electrode arrangements 1 shown in Fig.1 and 2 represent a bi-cell design and can be manufactured with surface elements of 100 pm to 200 pm layer thickness per side.

[0036] Active materials such as NMC, LFP, LiMn x Free. x PO4 (LMFP), LiCoO2 (LCO), LiM^C (LMO), Li(Ni x Mn2- x)C>4 (LNMO) as materials for cathode surface elements and graphite, LTO and silicon graphite as materials for anode surface elements are suitable for the asymmetric electrode design described by the electrode arrangement according to the invention. The openings can be created using laser ablation. When designing the electrode designs, the so-called cell balancing factor must be taken into account in order to avoid lithium plating. This means that the ratios of the surface capacities (capacitance of the anode divided by the capacitance of the cathode) should be within a defined range, typically in the range of 1.05 - 1.3. For example, this means that the unstructured anode (type A) must be designed somewhat thinner than the structured side of the double-sided coated cathode in order to keep the cell balancing factor at 1.05 - 1.3.Compared to symmetrically structured electrodes, asymmetrically structured electrodes exhibit a higher active mass: The "mass loss" for asymmetric electrode pairs (compared to unstructured electrodes) is only approximately 3%, which is significantly lower than the mass loss for symmetrically structured electrodes, which is 10-20%. In the case of a mixed embodiment with two asymmetric electrode pairs, the mass loss is also less than 12%, but only 7%.

[0037] LIST OF REFERENCE SYMBOLS

[0038] 1 Electrode arrangement

[0039] 10, 20 two layers 11 , 21 elongated anode surface elements

[0040] 12, 22 elongated cathode surface elements

[0041] 13, 23 separator layers

[0042] 14, 24 breakthroughs

[0043] 15, 25, 26 current collectors

Claims

PATENT CLAIMS 1. Electrode arrangement (1) designed for arrangement in a battery, wherein the electrode arrangement (1) comprises at least - two layers (10, 20) each comprising a pair of electrodes, each having an elongated anode surface element (11, 21) and an associated elongated cathode surface element (12, 22), which are each arranged one above the other separated by a separator layer (13, 23), characterized in that at least one of the anode surface elements (11, 21) or the cathode surface elements (12, 22) has a surface shape with openings (14, 24), and that this at least one anode or cathode surface element (11, 21, 12, 22) differs from the second elongated associated anode or cathode surface element (11, 21, 12, 22) with respect to its surface shape, wherein the electrode pair has an asymmetric forms a pair of electrodes.

2. Electrode arrangement (1) according to claim 1, characterized in that each of the at least two layers (10, 20) provides an asymmetrical electrode pair of the electrode arrangement.

3. Electrode arrangement (1) according to claim 1, characterized in that the surface elements (11, 12, 21, 22) of a layer (10, 20) of the at least two layers (10, 20) which does not provide the asymmetric element of the electrode arrangement have surface shapes of congruent surface elements (11, 12, 21, 22) with openings (14, 24).

4. Electrode arrangement (1) according to at least one of claims 1 to 3, characterized in that the openings (14, 24) in the at least one surface element (11, 12, 21, 22) are grooves, channels, blind holes or openings.

5. Electrode arrangement (1) according to at least one of claims 1 to 4, characterized in that the surface elements (11, 12, 21, 22) are thick-film electrodes and have a predetermined layer thickness in a range from 70 pm to 250 pm, preferably in a range from 100 pm to 200 pm, particularly preferably 150 pm.

6. Electrode arrangement (1) according to at least one of claims 1 to 5, characterized in that a current collector (15, 25, 26) is adjacent to each of the anode surface elements (11, 21) and the cathode surface elements (12, 22).

7. Battery with an electrode arrangement, characterized in that the electrode arrangement is an electrode arrangement (1) according to at least one of claims 1 to 6.

Images