Battery cell, battery and vehicle

Abstract

Battery cell (20) comprising a first electrode arrangement (51) and a second electrode arrangement (52), wherein the first electrode arrangement (51) comprises a first active material layer arrangement (54), wherein the first active material layer arrangement (54) comprises a first layer (81), wherein the first layer (81) comprises at least one anode material from an anode material group consisting of graphite-silicon-carbon, and-silicon-composite-graphite, wherein a second layer (83; 83A, 83B) is arranged at least partially on at least one outer surface of the first layer (81), which second layer (83; 83A, 83B) comprises vertical graphene, wherein the vertical graphene is doped, and wherein a silicon-carbon coating (82; 82A, 82B) is arranged at least partially on the first layer (81).

Description

The invention relates to a battery cell, a battery and a vehicle. CN 1 05 140 490 A discloses a process for manufacturing a flexible positive electrode for a lithium-sulfur battery. This involves forming nitrogen-doped, porous carbon fibers between the graphene sheet layers. CN 1 08 963 215 A shows a flexible substrate made of N-doped graphene on which porous MoS2 nanomaterial with a three-dimensional structure is fixed. CN 1 08 199 014 A shows a porous, nitrogen-doped, foamed composite material made of carbon and CN 1 16 031 424 A shows a composite electrode comprising a porous carbon electrode body and three-dimensionally formed graphene on the surface of the electrode body. The surface of the three-dimensional graphene is doped. The three-dimensionally formed graphene can be arranged vertically. It is therefore an object of the invention to provide a new battery cell, a new battery and a new vehicle. These tasks are solved by the subject matter of the independent claim and the subsidiary claims. A battery cell comprises a first electrode arrangement and a second electrode arrangement, wherein the first electrode arrangement comprises a first active material layer arrangement, and wherein the first active material layer arrangement comprises a first layer, the first layer comprising at least one anode material from an anode material group consisting of graphite, silicon oxide, silicon-carbon, silicon composite, and silicon composite / graphite, wherein a second layer is arranged at least partially on at least one outer surface of the first layer, the second layer comprising vertical graphene, the vertical graphene being doped. The first layer is protected by the second layer, and the vertical graphene can compensate for the volume change occurring in the first layer during a charging cycle. The doped vertical graphene also has good electrical properties. The first layer has at least a portion of a silicon-carbon coating. Silicon has a high specific capacity and enables a high energy density. The silicon-carbon coating is located between the first and second layers, or it is located on one side of the first layer where no second layer is present. According to a preferred embodiment, the silicon-carbon coating is designed as an amorphous silicon-carbon coating. This already enables partial compensation of the volume change of the silicon during a charging cycle. According to a preferred embodiment, the first layer comprises graphite at least in certain areas, with a silicon-carbon coating arranged on the graphite. This combination has proven advantageous for energy density and manufacturing. According to a preferred embodiment, the doping comprises at least one substance from a doping substance group consisting of nitrogen, phosphorus, carbon, fluorine, and titanium dioxide. These substances have produced good results in experiments. According to a preferred embodiment, the doping comprises carbon, wherein the carbon is at least partially in a form of carbon consisting of a group of forms including carbon black, diamond, graphite, fullerene, carbon nanotubes, and aerographite. These shapes have advantageous electrical properties. According to a preferred embodiment, the first layer is surrounded by the second layer on at least two sides. This provides good mechanical protection for the first layer. According to a preferred embodiment, the first electrode arrangement comprises a first conductive foil. The conductive foil enables good electrical conductivity. According to a preferred embodiment, the first active material layer arrangement is arranged on one side of the first current collector foil or on two opposite sides of the first current collector foil. According to a preferred embodiment, the second electrode arrangement comprises at least one material from a group of materials consisting of: lithium iron phosphate, lithium manganese iron phosphate, lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.2Co0.2O2 (NMC622), lithium nickel manganese cobalt oxide according to the formula LiNi0.5Mn0.3Co0.2O2 (NMC532), lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.1Co0.3O2 (NMC613), and lithium nickel manganese cobalt oxide according to the formula LiNi0.8Mn0.1Co0.1O2 (NMC811). These second electrode arrangements can advantageously be combined with the first electrode arrangement. According to a preferred embodiment, the first electrode arrangement is the anode, and the second electrode arrangement is the cathode. A battery contains such battery cells. Such a battery offers excellent properties with regard to fast charging and energy density. A vehicle has such a battery. This enables a long range and fast charging. Further details and advantageous embodiments of the invention will become apparent from the exemplary embodiments described below and illustrated in the drawings, which are in no way to be understood as limiting the invention, as well as from the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the present invention. The figures show: Fig. 1 in a side view of an electrode arrangement, Fig. 2 in a schematic top view of the electrode arrangement of Fig. 1, Fig. 3 in a schematic longitudinal section of a battery cell with electrode arrangements of Fig. 1, Fig. 4 in a schematic sectional view of a first embodiment of an active material layer arrangement, Fig.Fig. 5 shows a second embodiment of an active material layer arrangement in a schematic sectional view, and Fig. 6 shows a vehicle with a battery in a schematic representation. In the following, identical or similarly functioning parts are designated with the same reference symbols and are usually described only once. The description builds upon itself across figures to avoid unnecessary repetition. Fig. 1 shows a side view of an electrode arrangement 51 or 52, which comprises an electrode 61 or 62 and a strip element 55 or 56. Such strip elements 55, 56 serve to contact the electrode 61 or 62. The electrode 61 or 62 has a longitudinal direction 91 and a transverse direction 92 perpendicular to the longitudinal direction. Fig. 2 shows in a schematic top view the electrode arrangement 51, 52 of Fig. 1 . The electrode arrangement 51 or 52 comprises a film 53, also referred to as a current collector film, which acts as an electrical conductor and enables current flow. The film 53 forms the strip element 55, 56 in its edge region. In the region of the electrode 61, 62, an active material layer arrangement 54 is provided on one side or on both sides of the film 53. The thickness 93 of the electrode 61, 62 is preferably in the range of 15 µm to 2 mm. The strip element 55 or 56 is preferably at least partially or completely free of the active material layer arrangement 54, since this area is not effective for the galvanic cell. Furthermore, the strip element 55 or 56 without the active material layer arrangement 54 has a smaller thickness 94 than in the area of ​​the electrode 61 or 62, which allows for better bending of the strip element 55 or 56 and a more compact design in the contact area. The thickness 94 of the strip element 55 or 56 is preferably in the range of 4 µm to 50 µm. The electrode arrangement 52 preferably comprises at least one material from a group of materials consisting of: lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.2Co0.2O2(NMC622), lithium nickel manganese cobalt oxide according to the formula LiNi0.5Mn0.3Co0.2O2(NMC532), lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.1Co0.3O2(NMC613), and lithium nickel manganese cobalt oxide according to the formula LiNi0.8Mn0.1Co0.1O2(NMC811). Tests have shown that these materials enable rapid charging. Fig. 3 shows a schematic representation of a battery cell 20 from above in a longitudinal section. The battery cell 20 has a schematically indicated housing 68. An electrode stack arrangement 50 comprises electrode arrangements 51 and electrode arrangements 52. Separators 63 are provided between the electrodes 61 of electrode arrangements 51 and the electrodes 62 of electrode arrangements 52. In the exemplary embodiment, electrodes 61 and electrodes 62 are always arranged alternately. It is also possible to provide at least partially – e.g., in the middle – two identical electrodes 61 or two identical electrodes 62 adjacent to each other. An electrolyte 64 is provided to enable an ion flow. The electrodes 61 and 62 extend in their longitudinal direction 91 between the strip elements 55 and 56. Preferably, all electrodes 61, 62 extend in the same longitudinal direction 91. However, the longitudinal direction 91 can also differ, at least partially. The strip elements 55 of the electrode arrangements 51 are provided on a first side 95 of the electrode arrangements 51, 52 or the electrode stack arrangement 50, and the strip elements 56 are preferably positioned on a second side 96 of the electrode arrangements 51, 52 or the electrode stack arrangement 50, opposite the first side 95. Alternatively, both strip elements 55, 56 can be positioned on the same side, whereby a short circuit is prevented by the design of the strip elements 55, 56. Preferably, the battery cell 20 is designed as a lithium-ion battery cell. The electrode arrangement 51 preferably comprises a foil 53 made of copper or a copper alloy. The electrode arrangement 52 preferably comprises a foil 53 made of aluminium or an aluminium alloy. The active material layer arrangements 54 can each additionally contain additives. Preferably, the battery cell 20 is rechargeable, and such a battery cell 20 is also referred to as a secondary cell or secondary element. The strip elements 55, 56 are also referred to as current collector foils or current collector foils. Preferably, the first electrode arrangement 51 is the anode and the second electrode arrangement 52 is the cathode. Fig. 4 shows the active material layer arrangement 54 in a first embodiment. The active material layer arrangement 54 has a layer 81, wherein the layer 81 comprises at least one anode material from an anode material group consisting of graphite-silicon-carbon, and silicon-composite-graphite. Silicon composite graphite contains a combination of silicon carbon and graphite. On the opposite outer sides of layer 81, at least in some areas, layers 83A and 83B are arranged. Layers 83A and 83B exhibit vertical graphene. The vertical graphene is doped. Vertical graphene (VG) is composed of two-dimensional carbon units oriented in a direction perpendicular to the layer. This results in a three-dimensional structure within the layer. A silicon-carbon coating 82A, 82B (Si-C coating) is preferably arranged at least partially on layer 81, wherein the silicon-carbon coating 82A, 82B is preferably designed as an amorphous silicon-carbon coating. A common method for producing vertical graphene is plasma-enhanced chemical vapor deposition (PEC). Layer 81 preferably has graphite at least in some areas, and the silicon-carbon coating 82A, 82B is arranged on the graphite. The doping preferably comprises at least one dopant from a dopant group consisting of nitrogen (N), phosphorus (P), carbon (C), fluorine (F), and titanium dioxide (TiO2). The carbon preferably has a form other than graphene. The doping preferably consists of carbon, wherein the carbon is at least partially doped in a form of carbon from a group of forms consisting of: carbon black, diamond, graphite, fullerene, carbon nanotubes, and aerographite. Carbon black is a black, powdery solid consisting of 80% to 99.5% carbon, depending on its quality and application. Industrial carbon black (CAS No.: 1333-86-4) is a carbon black specifically produced as an industrial raw material and is the preferred choice. By design, industrial carbon black is a modification of carbon with a high surface area to volume ratio. The active material layer arrangement 54 can be arranged on one side of the current collector foil 53 or on two opposite sides of the current collector foil 53, see Fig. 2 . The active material layer arrangement 54 enables a fast charging process. The use of pure graphite in the active material layer arrangement 54 is advantageous with regard to lifetime and cost. However, pure graphite is only conditionally suitable for fast charging. Firstly, the lithiation voltage is low, at 0.08 V relative to Li / Li+. Secondly, the intercalation kinetics are comparatively slow. The specific capacity of graphite is 372 mAh g⁻¹. This is relatively low. Silicon has a higher specific capacity of 4,200 mAh g⁻¹ and a safe lithium alloy potential of 0.22 V compared to Li / Li⁺. However, other problems arise when using silicon. Firstly, a comparatively large volume change occurs during cycling, which can lead to mechanical stresses. Secondly, its electrical conductivity is low, at approximately 10⁻⁴ S m⁻¹. In practice, the use of silicon-carbon anodes leads to unsatisfactory results under industrial conditions due to the large volume change and slow charge transport capability, particularly with regard to cycle stability and fast charging capability. A graphite layer 81, on which a silicon-carbon layer is deposited, has proven advantageous for the active conductor material layer arrangement 54. The silicon-carbon layer leads to a strong acceleration of electron and lithium ion transport. The silicon-carbon layer is preferably amorphous. Preferably, the silicon-carbon layer is deposited homogeneously. Preferably, the silicon-carbon layer is formed as a nanolayer. Here, the silicon particles are arranged in a 3D carbon framework, and this already leads to a reduction in volume change during charging cycles. Layers 83A and 83B feature vertical graphene with a doping layer. Vertical graphene with a doping layer has a porous structure, good flexibility, numerous exposed edges, and directed ion transport channels. This allows layers 83A and 83B to partially or completely compensate for the volume change of silicon, and the mechanical stress within the active conductor material layer assembly 54 is reduced. The vertical graphene can be figuratively viewed as armoring layer 81 and layers 81 and 82, respectively. The electrical contact points between the silicon are increased. In combination with graphite, silicon carbon and vertical graphene, this results in a high speed capacity and a long cycle life under industrial electrode conditions in the automotive sector. A combination of such an electrode arrangement 51 with one of the electrode arrangements 52 listed in Fig. 2 has resulted in very good fast charging capability in tests. For example, when combined with an electrode array made of NMC811, charging in under 8 minutes was achieved. The C-rating for the charging speed was 5C. Simultaneously, a long cycle life is possible, with more than 1,000 cycles. Fig. 5 shows the active material layer arrangement 54 in a second embodiment. In this embodiment, layer 81 containing the anode material is surrounded by layer 83 only on one side. In this embodiment, the silicon-carbon coating 82 is also arranged at least partially on layer 81. The silicon-carbon coating 82 can also be provided on both sides of layer 81. Layer 83, which serves as mechanical protection, already provides protection when applied to only one side. Fig. 6 shows a vehicle 10. The vehicle 10 has a battery 12. The battery 12 is connected, for example, to a drive motor 16 for the vehicle via an electronic circuit 14. Such batteries 12 are also called traction batteries. Battery 12 has several battery cells 20. Naturally, various variations and modifications are possible within the scope of the present invention. With regard to cell chemistry, the invention is not limited to a specific cell chemistry. A standard lithium-ion cell, a lithium-ion cell with advanced chemistry, a Si-rich chemistry, a Ni-rich chemistry, LFP, LMFP, NMC (NMC 622-, NMC532-, NMC613-, NMC811-) Na-ion, hybrid semi-solid, dense solid state, semi solid state and all solid state cell can be used.

Claims

Battery cell (20) comprising a first electrode arrangement (51) and a second electrode arrangement (52), wherein the first electrode arrangement (51) comprises a first active material layer arrangement (54), wherein the first active material layer arrangement (54) comprises a first layer (81), wherein the first layer (81) comprises at least one anode material from an anode material group consisting of graphite-silicon-carbon, and-silicon-composite-graphite, wherein a second layer (83; 83A, 83B) is arranged at least partially on at least one outer surface of the first layer (81), which second layer (83; 83A, 83B) comprises vertical graphene, wherein the vertical graphene is doped, and wherein a silicon-carbon coating (82; 82A, 82B) is arranged at least partially on the first layer (81). Battery cell (20) according to claim 1, in which the silicon-carbon coating (82; 82A, 82B) is designed as an amorphous silicon-carbon coating. Battery cell (20) according to one of the preceding claims, wherein the first layer (81) has graphite at least in certain areas, wherein the silicon-carbon coating (82; 82A, 82B) is arranged on the graphite. Battery cell (20) according to one of the preceding claims, wherein the doping comprises at least one substance from a doping substance group consisting of nitrogen (N), phosphorus (P), carbon (C), fluorine (F), and titanium dioxide (TiO2). Battery cell (20) according to one of the preceding claims, wherein the doping comprises carbon (C), the carbon being at least partially in a form of carbon consisting of a group of forms consisting of - carbon black, - diamond, - graphite, - fullerene, - carbon nanotubes, and - aerographite. Battery cell (20) according to one of the preceding claims, wherein the first layer (81) is surrounded on at least two sides by the second layer (83; 83A, 83B). Battery cell (20) according to one of the preceding claims, wherein the first electrode arrangement (51) comprises a first conductor foil (53). Battery cell (20) according to claim 7, wherein the first active material layer arrangement (54) is arranged on one side of the first current collector foil (53) or on two opposite sides of the first current collector foil (53). Battery cell (20) according to one of the preceding claims, wherein the second electrode arrangement (52) comprises at least one material from a group of materials consisting of: lithium iron phosphate (LFP), lithium manganese iron phosphate (LMFP), lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.2Co0.2O2(NMC622), lithium nickel manganese cobalt oxide according to the formula LiNi0.5Mn0.3Co0.2O2(NMC532), lithium nickel manganese cobalt oxide according to the formula LiNi0.6Mn0.1Co0.3O2(NMC613), and lithium nickel manganese cobalt oxide according to the formula LiNi0.8Mn0.1Co0.1O2(NMC811). Battery cell (20) according to one of the preceding claims, wherein the first electrode arrangement (51) is the anode and the second electrode arrangement (52) is the cathode. Battery (12) comprising battery cells (20) according to any of the preceding claims. Vehicle (10) which has a battery (12) according to claim 11.

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