Cathode material

Abstract

The invention relates to a cathode material (26) comprising an active material (28) and a further material (34), namely a carbon-based binder (30) and / or a conductive additive (32). The further material (34) is provided with a lithium ion (36). The invention further relates to a method (44) for producing a cathode (18).

Description

[0001] The invention relates to a cathode material and a method for producing a cathode.

[0002] Motor vehicles are increasingly being powered at least partially by an electric motor, so that they are designed as electric vehicles or hybrid vehicles. A high-voltage battery comprising several individual battery modules is typically used to power the electric motor. The battery modules are usually identical in construction and are electrically connected in series and / or parallel, so that the electrical voltage applied to the high-voltage battery corresponds to a multiple of the electrical voltage provided by each of the battery modules. Each battery module, in turn, comprises several batteries, which are usually arranged in a common housing and are electrically connected in series and / or parallel.

[0003] Each battery comprises one or more battery cells, also known as galvanic cells. Each battery cell has two electrodes, namely an anode and a cathode, as well as a separator arranged between them and an electrolyte with freely moving charge carriers. A liquid, for example, is used as such an electrolyte. In an alternative, the battery cell is designed as a solid-state battery, and the electrolyte is in the form of a solid.

[0004] The anode and cathode, which form the electrodes of the battery (cell), typically comprise a conductor / carrier that acts as a current collector. An active material suitable for absorbing the working ions, e.g., lithium ions, is usually attached to this conductor / carrier. The active material is a component of a layer made of an electrode material and applied to the carrier. In addition to the active material, the electrode material also contains a conductive additive that provides electrical conductivity. Conductive carbon black, for example, is used as such a conductive additive. The electrode material also comprises a binder that holds the active material and the conductive carbon black together and provides mechanical stabilization. Polyvinylidene fluoride (PVDF) is typically used as the binder.

[0005] Both the conductive additive and the binder are non-conductive to lithium ions and therefore do not participate in the battery's charge / discharge process. Typically, the conductive additive content of the electrode material is in the range of 2-4%, while the binder content is 2-3%. This reduces energy density. Reducing the binder content would lead to adhesion problems, and reducing the conductive additive content would reduce electronic conductivity. Thus, approximately 5% of the electrode material is inactive material, and only 95% of the electrode material provides the electrical capacity of the respective electrode.

[0006] After the electrode material has been applied to the conductor, the formed layer has a comparatively high porosity and therefore a comparatively low density. This also results in a comparatively low energy density. To increase the energy density, it is therefore necessary to increase the density of the layer, for which a calender is typically used. This compresses the layer, with the force being applied to the outer surfaces of the layer, which is why it is compressed more intensively there. As a result, the pores there are comparatively closed, so that subsequent penetration of the electrolyte into the layer is slowed / made more difficult. It is therefore necessary to soak the layer with the electrolyte for a comparatively long period of time until the battery is ready for use. This leads to increased production costs.

[0007] The invention is based on the object of specifying a particularly suitable cathode material and a particularly suitable method for producing a cathode, wherein production costs are advantageously reduced and / or an energy density is increased, and wherein a service life is expediently extended.

[0008] With regard to the cathode material, this object is achieved according to the invention by the features of claim 1 and with regard to the method for producing a cathode by the features of claim 8. Advantageous further developments and refinements are the subject of the respective subclaims.

[0009] The cathode material serves to produce a cathode. In other words, it is possible to use the cathode material to produce a cathode, and the cathode material is suitable, in particular provided and configured, for this purpose. The cathode, in turn, is a component of a battery when used as intended. The battery is in particular rechargeable and is thus a secondary battery. The battery further comprises an anode associated with the cathode. The battery expediently comprises a plurality of such anodes and cathodes, which together form the electrodes of the battery. A separator is expediently arranged between each anode and each cathode, and the battery preferably comprises an electrolyte that provides a number of freely mobile charge carriers, such as lithium ions.For example, the electrolyte is a component of the anode and / or cathode, or is at least suitable for accumulating there and thus being absorbed by them. The battery is, for example, a solid-state battery, so the electrolyte is present as a solid. Alternatively, the electrolyte is liquid. The battery has, in particular, a housing in which the electrodes / electrolytes / separators are arranged. In particular, the housing is made of a metal, for example a steel such as stainless steel, or an aluminum alloy. A die-casting process, for example, is used to produce the respective housing. In particular, the housing is designed to be sealed.

[0010] In its intended state, the battery is preferably a component of a motor vehicle. The battery is suitable, in particular provided and configured, for this purpose. In its intended state, the battery is, for example, a component of an energy storage device of the motor vehicle, which has a plurality of such batteries. The battery is preferably divided into a plurality of battery modules, which in turn are structurally identical to one another. The motor vehicle is preferably land-based and preferably has a number of wheels, of which at least one, preferably several or all, are driven by a drive. Suitably, one, preferably several, of the wheels is designed to be steerable. This makes it possible to move the motor vehicle independently of a specific roadway, for example rails or the like.In this case, it is advantageously possible to position the motor vehicle essentially anywhere on a roadway, which is made, in particular, of asphalt, tar, or concrete. The motor vehicle is, for example, a commercial vehicle, such as a truck or a bus. However, the motor vehicle is particularly preferably a passenger car.

[0011] The motor vehicle is expediently moved by means of the drive. For example, the drive, in particular the main drive, is at least partially electric, and the motor vehicle is, for example, an electric vehicle. The electric motor is operated, for example, by means of the energy storage device, which is suitably designed as a high-voltage battery. A direct electrical voltage is expediently provided by the high-voltage battery, wherein the electrical voltage is, for example, between 200 V and 800 V and, for example, substantially 400 V. Preferably, an electrical converter is arranged between the energy storage device and the electric motor, by means of which the current supply to the electric motor is adjusted. In an alternative, the drive additionally has an internal combustion engine, so that the motor vehicle is designed as a hybrid motor vehicle.In an alternative, the energy storage device is used to feed a low-voltage electrical system of the motor vehicle, and the energy storage device is used to provide, in particular, an electrical direct voltage of 12 V, 24 V or 48 V.

[0012] In one alternative, the battery is a component of an industrial truck, an industrial plant, or a hand-held device, such as a tool, in particular a cordless screwdriver. In another alternative, the battery is a component of an energy supply and is used there, for example, as a so-called buffer battery. In another alternative, the battery is a component of a portable device, such as a portable mobile phone or other wearable. It is also possible to use such a battery in camping, model making, or other outdoor activities. In another alternative, the battery is a component of a charging station, such as a charging column, a drone or other aircraft, an e-scooter, an e-bike, or a portable computer, such as a laptop.

[0013] The cathode material is expediently in powder form, especially if it has not yet been processed into a cathode. This is thus an electrode powder mixture, also referred to as an electrode blend, with the electrode being the cathode of the battery. Alternatively, the cathode material can be liquid or pasty, for example. If the cathode is in its intended state, and in particular forms a component of the battery, the cathode material is expediently in solid form.

[0014] The cathode material comprises an active material and another material. The active material is preferably suitable, intended, and configured to accommodate working ions. Lithium ions are used as the working ions. A metal oxide, preferably LiwNixCoyMnzO2 (w=0.8-1.4; x+y+z = 1), an olivine such as LiFePO4, or a spinel such as LiNi0.5Mn1.5O4, is used as the active material. A lithium metal oxide, such as lithium cobalt(III) oxide (LiCoO2), NMC, NCA, LFP, LTO, LNMO, LMO, lithium, or LiPO4, is used as the active material. For example, NMC622 or NMC811 is used as the active material for the cathode.

[0015] The additional material is a binder or a conductive additive. In other words, the binder or conductive additive forms the additional material. In an alternative, the additional material is formed from the binder and the conductive additive, i.e., in particular, from a mixture of the conductive additive and the binder. The active material and the additional material are expediently present as a mixture in the cathode material.

[0016] The binder serves in particular to mechanically stabilize / bond the active material to the other components of the cathode material. The conductive additive, on the other hand, serves to conduct electrons. In other words, the conductive additive has conductivity for electrons. The conductive additive is carbon-based and thus comprises carbon atoms, which provide electrical conductivity. In summary, the conductive additive is thus suitable, in particular intended, and configured for electron conduction. For example, the cathode material consists solely of the active material and the additional material. Alternatively, for example, the additional material is formed solely by means of the binder, and the cathode material is formed by means of the active material, the additional material, and one or more of the conductive additives.If, however, the further material is formed only by means of the conductive additive, the cathode material expediently comprises the active material, the further material and a binder.

[0017] The additional material is provided with a lithium ion. In other words, the binder or the conductive additive, or both, contains a lithium ion. Suitably, the molecule or substance from which the binder or the conductive additive is formed, i.e., in particular, the individual particles of the additional material, comprises the lithium ion, which is bonded, for example, ionically, covalently, or metallically, to another atom of the additional material. Each molecule is expediently assigned several lithium ions. Due to the inclusion of the lithium ion, the additional material is conductive to lithium ions. In other words, the additional material has conductivity for lithium ions.

[0018] The addition of the lithium ion increases the energy density. The lithium ion in the additional material also contributes to the lithium ion conductivity of the cathode material. This increases the number of possible paths for the working ions (lithium ions). The path length (tortuosity) is also reduced. The increased lithium ion conductivity also improves lithium ion transport during charging and discharging. It is also possible to compress the cathode material comparatively strongly, thus reducing porosity. The conductivity of the additional material for lithium ions also enables penetration of lithium ions. The comparatively low porosity of the cathode created using the cathode material further increases the energy density. The required amount of electrolyte is also reduced, which further increases the energy density.Since the conductivity for lithium ions is provided by the additional material, it is not necessary to modify existing machines and / or methods / processes for manufacturing the battery, so there is no additional effort.

[0019] If the conductive additive contains a lithium ion, additional deposition of PF6 anions is not possible, even at an elevated electrical voltage applied to the battery, such as 4.5 V. Since deposition is prevented, the subsequent release of the fluorine ion, which would otherwise react with a hydrogen ion to form hydrogen fluoride, is also prevented. The lithium ion does not impair electronic conductivity. Due to the lithium (ion) conductivity of the conductive additive, oxidation of the electrolyte by the conductive additive is also reduced / prevented, so that no decomposition products of the electrolyte attach to the conductive additive. Thus, electronic conductivity is not impaired due to a reaction between the conductive additive and the electrolyte, even after a long battery life.

[0020] For example, a surface of the additional material is provided with a coating comprising the lithium. Due to the arrangement of the lithium ion on the surface, lithium ion conductivity is comparatively high. For example, each particle of the additional material is provided with the coating, or a group of several particles is provided with the coating. For example, the coating is only partially present, so that the other properties of the additional material, in particular the adhesion to the individual components / particles, if the additional material is provided by means of the binder, and / or the electronic conductivity if the additional material is at least partially formed by means of the conductive additive, are not impaired. Advantageously, 80%-90% of the surface is coated.Thus, the other properties / requirements for the other material are still met, with a comparatively high lithium ion conductivity being provided.

[0021] Advantageously, a defect or similar site is first formed on the surface of the further material for coating, so that attachment there is simplified. In particular, a functional group, in particular LI-OH or LI-O, is attached to the surface to provide it. Preferably, the further material is exposed to lithium vapors. The surface is thus preferably vapor-deposited with lithium. The lithium is reduced on the surface of the further material, so that lithium carbonate, lithium oxide, lithium peroxide and / or lithium hydroxide forms there and adheres to the surface. This simplifies production, and the compound is comparatively stable.

[0022] For example, no further processing is carried out after exposure to the lithium vapors and the corresponding reduction. In other words, the coating expediently comprises lithium carbonate, lithium oxide, lithium peroxide, and / or lithium hydroxide. However, the additional material is particularly preferably coated with a lithium phosphate (Li3PO4). For example, the coating comprises lithium phosphate, or particularly preferably, the coating consists of lithium phosphate. For production, the functional group is expediently first deposited on the surface, in particular by using lithium vapors. Thus, lithium carbonate, lithium oxide, lithium peroxide, and / or lithium hydroxide adhere to the surface. The surface treated in this way is then exposed to phosphoric acid (H3PO4). This reacts with the functional groups deposited on the surface: 3(Li2O) + 2(H3PO4) -> 2(Li3PO4) + 3(H2O) 3(LiOH) + H3PO4 -> Li3PO4 + 3(H2O) 3(Li2CO3) + H3PO4 -> 2(Li3PO4) + 3(CO2) + 3(H2O)

[0023] In summary, Li3PO4 forms, which adheres to the outer surface of the additional material. The lithium ion conductivity of Li3PO4 is such that the cathode material exhibits a comparatively high conductivity. The invention also relates in particular to a method for producing the additional material, the surface of which is provided with the coating comprising the lithium ion, according to the variants mentioned above.

[0024] For example, the lithium ion is embedded in a crystalline part of the additional material. For example, the additional material is formed solely by a single crystal, or it contains additional components in addition to the crystalline part. In this case, the additional material is particularly amorphous. Because the lithium ion is embedded, detachment from the additional material is more difficult, thus increasing the stability of the cathode material, and a cathode produced with it exhibits the same properties over a comparatively long period of time.

[0025] Storage is carried out, for example, by calcination. For this purpose, the additional material and a lithium-containing material, preferably a lithium carbonate or lithium hydroxide, are mixed and melted. For this purpose, heating to over 350 °C or 800 °C is carried out. During subsequent cooling, the crystalline part is recreated, in which the lithium ions are then stored. Alternatively, or in combination with this, a solid-state diffusion process is used for storage. In another alternative, lithium metal is used, to which an electrical potential is applied. An electrical potential is also applied to the additional material, so that an electrical voltage is created between them. This is in particular 4.5 V, and the additional active material serves as the cathode. Due to the applied electrical voltage, lithium ions diffuse into the additional material, so that the additional material is pre-lithiated.In another alternative, the active material diffuses into the additional material, thereby doping it. In a further development, lithium silicates are used. For this purpose, the additional material, in particular the individual particles, is first coated with SiOx, which is then lithiated to form lithium silicates. The lithium from lithium phosphate or lithium silicate then diffuses into the crystalline part. If there is an excess of SiOx, it adheres to the surface of the additional material, so that the excess is also present in the battery. In other words, the additional material has a lithium-conductive coating, which acts as an active material during operation to store lithium, thus increasing the battery capacity.If, in one of the variants mentioned, lithium ions still adhere to the surface of the additional material and are thus retained, a lithium hydroxide and lithium oxide layer forms on the surface due to a reaction with the ambient air. These lithium impurities are preferably converted into a conductive lithium-ion coating by reaction with H3PO4 acid. Thus, the additional material has the embedded lithium ion and is additionally provided with the coating containing the lithium ion, so that the number of lithium ions is increased. The invention also relates in particular to a method for producing the additional material with the embedded lithium ion according to the variants mentioned above.

[0026] Alternatively or in combination with this, the further material comprises a polymer. However, this is not a homopolymer, but rather a copolymer. Here, the copolymer comprises a lithium-based functional group. In other words, one or more hydrogen ions are substituted by a lithium ion. For example, before being provided with the lithium ion, the further material has a functional group with two carbon atoms. Two fluorine atoms are covalently bonded to one of the carbon atoms and two hydrogen atoms to the other. One or both of the hydrogen atoms is replaced by the lithium ion, so that the group has one or two lithium ions. In particular, the copolymer thus has the formula V2F-2Li or V2F-HLi. Thus, a comparatively high number of lithium ions is present, and the stability of the further material provided with the lithium ion is comparatively high.

[0027] For example, the binder is a homogeneous material. Particularly preferably, the binder is an amorphous material and, in particular, comprises the crystalline part, if any, or another crystalline part. The crystalline part, in particular, provides high mechanical integrity, and the additional components expediently provide, at least in part, electrode conductivity and / or flexibility.

[0028] In another alternative, the binder is a rubber, such as styrene-butadiene rubber (SBR) or acrylonitrile. Preferably, the binder is a polymer. In particular, a polyvinyl acetate (PVAC), a polymethyl methacrylate (PMMA), or cellulose nitrate is used as the binder. In another alternative, the binder is a fluoropolymer, such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), or vinylidene fluoride-hexafluoropropylene copolymer. Particularly preferably, the binder comprises polyvinylidene fluoride (PVDF) or is expediently formed therefrom. This reduces the number of different starting materials. Polyvinylidene fluoride has the crystalline part into which the lithium ion can be incorporated.In addition, it is possible to provide the surface, in particular at least the remaining part, with the coating comprising the lithium ion, so that a comparatively large number of lithium ions can be used.

[0029] Graphite, carbon nanotubes, carbon nanofibers, or carbon fibers, for example, are used as the conductive additive. Alternatively, a fullerene, i.e., spherical molecules made of plastic atoms, is used as the conductive additive. Conductive carbon black is particularly preferred as the conductive additive. In other words, the conductive additive comprises the conductive carbon black or is expediently formed with it. The use of conductive carbon black reduces manufacturing costs, while providing the lithium ion is comparatively easy. The conductive carbon black is particularly industrial carbon black, such as furnace black. This reduces manufacturing costs. Alternatively, acetylene black, for example, is used. This has a comparatively high purity, thus increasing performance.

[0030] The method for producing a cathode. In its intended state, the cathode is a component of a battery which further comprises an anode. A separator is arranged between the anode and the cathode. The battery expediently comprises an electrolyte. The method provides for a cathode material to be mixed with a non-aqueous solvent to form a paste, which is also referred to as a slurry. Before mixing, the cathode material is expediently in powder form. The cathode material comprises an active material and a further material, namely a binder and / or a carbon-based conductive additive. The further material is provided with a lithium ion. For example, for mixing, the cathode material is first created or at least prepared and then mixed with the solvent.Alternatively, the individual components of the cathode material are at least partially mixed with the solvent one after the other, so that the cathode material is not present alone, but only in dissolved form.

[0031] The paste is then applied to a conductor, preferably by coating / pouring or spraying. In a preferred alternative, the electrode powder mixture is applied to the conductor by electrostatic coating. This allows for even distribution of the electrode powder mixture on the conductor. Alternatively, a roller press, a calender, or a roller mill is used for this purpose. A doctor blade is expediently used to distribute the paste on the conductor. The conductor is made, in particular, of a metal, for example, a metal foil. Aluminum is more expediently used as the metal. The conductor is, in particular, flat or strip-shaped.

[0032] After being applied to the conductor, the paste is cured, which primarily involves removing the solvent. For this purpose, the conductor coated with the layer is expediently heated, irradiated with light, or subjected to a heated press. After curing, calendering is preferably carried out, for which purpose a calender is used, for example a 4-roll calender, so that the conductor is coated on both sides. The calender is used, particularly in a calendering process, to adjust the thickness of the cathode. This process enables a comparatively rapid production of the cathode, with the additional material increasing the lithium ion conductivity.

[0033] The invention further relates to a cathode produced in this way and to a battery having such a cathode or at least one cathode comprising the cathode material.

[0034] The advantages and further developments described in connection with cathode material can also be transferred to the processes / battery and to each other, and vice versa.

[0035] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In the drawings: Fig. 1 schematically shows a simplified version of a motor vehicle having a high-voltage battery with several identical batteries, Fig. 2 schematically shows a sectional view of one of the identical batteries, which comprises a cathode with a cathode material with a further material, wherein three different forms of the further material are shown, Fig. 3 a crystalline part of the further material, Fig. 4 the crystalline part in which a lithium ion is embedded, Fig. 5 a copolymer of the further material , Figures 6 and 7 show two different versions of the copolymer in which a lithium ion is embedded, Fig. 8 excerpts from the further material, Fig. 9 the further material on whose surface a functional group is attached, Fig. 10 the further material, the surface of which is provided with a coating comprising the lithium ion, and Fig. 11 a process for producing the cathode.

[0036] Corresponding parts are provided with the same reference numerals in all figures.

[0037] In Fig. 1 shows a simplified schematic representation of a motor vehicle 2 in the form of a passenger car (car). The motor vehicle 2 has a number of wheels 4, at least some of which are driven by a drive 6 comprising an electric motor. Thus, the motor vehicle 2 is an electric vehicle or a hybrid vehicle. The drive 6 has an inverter by means of which the electric motor is powered. The inverter of the drive 6, in turn, is powered by an energy storage device 8 in the form of a high-voltage battery. For this purpose, the drive 6 is connected to an interface 10 of the energy storage device 8, which is incorporated into a housing 12 of the energy storage device 8, which is made of stainless steel. Arranged within the housing 12 of the energy storage device 8 are several battery modules, some of which are electrically connected in series with one another and these, in turn, are electrically connected in parallel with one another.The electrical connection of the battery modules is electrically connected to the interface 10, so that the battery modules are discharged or charged (recuperated) when the drive 6 is operated. Due to the electrical interconnection, the electrical voltage provided at the interface 10, which is 400 V, is a multiple of the electrical voltage provided by the identically constructed battery modules.

[0038] Each of the battery modules, in turn, comprises several identical batteries 14, two of which are shown here. The batteries 14 are electrically connected to one another, partly in parallel and partly in series, so that the electrical voltage provided by each battery module is a multiple of the electrical voltage provided by one of the batteries 14.

[0039] In Fig. Figure 2 is a schematic sectional view of a section of one of the identical batteries 14. A housing for the battery 14 is not shown. Arranged within the housing are a plurality of identical anodes 16 and cathodes 18, each of which has a flat design, and only two of which are shown here. The anodes 16 and the cathodes 18 are stacked one above the other, with a separator 20 arranged between each of them. The anodes 16 and the cathodes 18 are of similar construction and each have a conductor 22 made of a metal foil and arranged parallel to the separator 20. The conductor 22 is provided with a layer 24 on each side. One of the layers 24 assigned to the cathode 18 is shown enlarged for clarity, but the layers 24 are essentially the same size.The conductor 22 of the anodes 16 is made of copper foil, whereas the conductor 22 of the cathodes 18 is made of aluminum foil. The layers in the anode 16 are made of an anode material comprising an active material (not shown in detail), a binder, and a conductive additive. The layers 24 of the cathode 18, on the other hand, are made of a cathode material 26.

[0040] The cathode material 26 comprises an active material 28, a binder 30, and a conductive additive 32. The active material 28 is LNMO, the binder 30 is polyvinylidene fluoride (PVDF), and the conductive additive 32 is conductive carbon black, for example, furnace black or acetylene black. Consequently, the conductive additive 32 is a carbon-based conductive additive. A further material 34 is provided by means of the binder 30 and / or the conductive additive 32. Thus, three different forms of the further material 34 are possible, of which only one is used for the same cathode material 26. In other words, three different configurations of the cathode material 26 are possible.

[0041] In one variant, the additional material 34 only has the binder 30, and in another only the conductive additive 32. In the last variant, however, the additional material for 34 comprises both the binder 30 and the conductive additive 32. The additional material 34 is each provided with a lithium ion 36. If the additional material 34 therefore only has the binder 30, this, i.e. the polyvinylidene fluoride, is provided with the lithium ion 36. The conductive additive 32, on the other hand, does not comprise an additional lithium ion. If the additional material 34 only comprises the conductive additive 32, the conductive carbon black is provided with the lithium ion 36, but not the binder 30. The conductive additive 32, on the other hand, does not comprise an additional lithium ion. If both the binder 30 and the conductive additive 32 are assigned to the additional material 34, both of them are each provided with the lithium ion 36.It is not necessary for the binder 30 and the conductive additive 32 to form a specific bond together; they can also be mechanically separated from each other. Due to the additional lithium ion 36, the binder 30 and the conductive additive 32 also contribute to the lithium ion conductivity. This accelerates the charging and discharging process of the battery 14. Penetration of lithium ions through the surface of the layer 24 is also facilitated, even if there is comparatively low porosity there.

[0042] If the conductive additive 32 comprises the lithium ions 36, the accumulation of further lithium ions or PF6 anions, which are provided, for example, by an electrolyte of the battery 14, is prevented during operation of the battery 14. As a result, the formation of fluorine ions, which would otherwise react with existing protons to form hydrogen fluoride, is also prevented. Thus, it is not necessary to provide corresponding degassing or safety precautions for the battery 14, and environmental compatibility is also improved. Since no undesired chemical reactions occur at the conductive additive 32, no reaction products from it accumulate on the conductive additive 32, which could otherwise reduce its electrical conductivity, i.e., its electronic conductivity. Thus, the battery 14 exhibits reduced aging effects and can be used for a comparatively long period of time.

[0043] To provide the lithium ion 36, this is, for example, incorporated into a crystalline part 38 of the further material 34, for example the binder 30 and / or the conductive additive 32, which is in Fig. 3 is shown schematically. In the variant shown, the crystalline part 38 has lattice structures extending in a first direction La, so that layers extending in this direction are formed, which are stacked one above the other in a second direction Lc extending perpendicular thereto. During storage, the lithium ions 36 are arranged between the individual layers of the crystalline part 38, as shown in Fig. 4. Thus, they are arranged in the second direction Lc between the respective layers of the crystalline part 38.

[0044] To store the lithium ions 36, in one variant, the additional material 34 and lithium metal are melted, for which purpose they are heated to 350°C or 800°C, depending on the use of the binder 30 or the conductive additive 32. After mixing, this mixture is cooled so that it crystallizes and the crystalline part 38 is reformed, in which the lithium ions 36 are stored. Alternatively, for example, lithium metal 38 is arranged next to the crystalline part and an electrical voltage, in particular 4.5 V, is applied to it, which leads to a diffusion of the lithium ions 36 into the crystalline part 38.

[0045] In an alternative, the additional material 34 has a Fig. 5. This comprises a functional group with two carbon atoms (C), to one of which two fluorine ions (F) and to the other two hydrogen ions (H) are covalently bonded. To provide the lithium ion 36, one of the hydrogen ions is replaced by the lithium ion 36, as shown in Fig. 6. In a further development, the remaining hydrogen ion is also substituted by a lithium ion 36, as in Fig. 7. Thus, the copolymer 40 and hence also the further material 34 have a comparatively large number of lithium ions 36, so that the ionic conductivity is further improved.

[0046] In Fig. 8 shows a further embodiment of the further material 34, which comprises long-chain molecules. The binder 30 and / or the conductive additive 32 is formed by means of the molecules. At each molecule, as in Fig. As shown in Figure 9, a functional group 42 is attached, namely Li-OH or Li2-CO3 or Li2-O. This is done by exposing the binder 30 or the conductive additive 32 to lithium vapors. In a subsequent step, the thus-treated molecule is exposed to phosphoric acid (H3PO4), forming lithium phosphate (Li3PO4): 3(Li2O) + 2(H3PO4) -> 2(Li3PO4) + 3(H2O) 3(LiOH) + H3PO4 -> Li3PO4 + 3(H2O) 3(Li2CO3) + H3PO4 -> 2(Li3PO4) + 3(CO2) + 3(H2O)

[0047] Using lithium phosphate, a Fig. 10, by means of which the respective molecule is coated. In other words, the further material 34 is coated with the lithium phosphate, and the surface of the further material 34 is provided with the coating 42 comprising the lithium ions 36.

[0048] In Fig.Figure 11 illustrates a method 44 for producing the cathode 18. In a first step, the cathode material 26 is provided, which comprises the active material 28 and the additional material 34. If the binder 30 or the conductive additive 32 are not part of the additional material 34, they are provided separately. The cathode material 26 is in powder form, in particular as a so-called "blend." The cathode material 26 is mixed with a non-aqueous solvent to form a paste, also referred to as a "slurry."

[0049] In a subsequent second step 48, the paste is applied to the conductor 22, i.e., the aluminum foil, and spread using a doctor blade. The paste is then cured, for which purpose, in particular, the aqueous solvent is evaporated. Thus, the layer 24 is formed, which essentially consists solely of the cathode material 26. In a subsequent third step 50, the conductor 22 provided with the layer(s) 24 is moved through a calender, by means of which a force is exerted on the layer 24. As a result, the cathode material 26 is compacted, and any existing pores are closed.

[0050] The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can also be derived therefrom by those skilled in the art without departing from the subject matter of the invention. In particular, all individual features described in connection with the individual exemplary embodiments can also be combined with one another in other ways without departing from the subject matter of the invention. List of reference symbols 2 motor vehicles 4 wheel 6 Drive 8 energy storage 10 Interface 12 housings 14 Battery 16 Anode 18 Cathode 20 Separator 22 arresters 24 shift 26 Cathode material 28 active material 30 binders 32 Lead additive 34 additional material 36 lithium ion 38 crystalline part 40 Copolymer 42 Coating 44 procedures 46 first step 48 second step 50 third step The first direction Lc second direction

Claims

[1] Cathode material (26) comprising an active material (28) and a further material (34), namely a binder (30) and / or a conductive additive (32) based on carbon, wherein the further material (34) is provided with a lithium ion (36). [2] Cathode material (26) according to claim 1, characterized by that a surface of the further material (34) is provided with a coating (42) comprising the lithium ion (36). [3] Cathode material (26) according to claim 2, characterized by that the further material (34) is coated with a lithium phosphate. [4] Cathode material (26) according to one of claims 1 to 4, characterized by that the lithium ion (36) is embedded in a crystalline part (38) of the further material (34). [5] Cathode material (26) according to one of claims 1 to 4, characterized by that the further material (34) comprises a copolymer (40) wherein a hydrogen ion is substituted by the lithium ion (36). [6] Cathode material (26) according to one of claims 1 to 5, characterized by that the binder (30) comprises a polyvinylidene fluoride. [7] Cathode material (26) according to one of claims 1 to 5, characterized by that the conductive additive (32) comprises a conductive carbon black. [8] Method (44) for producing a cathode (18), in which - a cathode material (26) according to one of claims 1 to 7 is mixed with a non-aqueous solvent to form a paste, - the paste is applied to a conductor (22) and cured there.

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