Method and apparatus for manufacturing electrodes for rechargeable batteries

Abstract

To provide a method and an apparatus for efficiently producing an electrode for a rechargeable battery that enable uniform application of an electrode material onto a carrier while minimizing the use of harmful solvents as much as possible.SOLUTION: The invention relates to a method for producing an electrode for a rechargeable battery, where an electrode compound is applied to a carrier, in particular metal foil, by means of an extrusion step. In the extrusion step, the electrode compound is fed through an extrusion die by means of a feeding device. The electrode compound is prepared by mixing in a mixing device and passed on from the mixing device to the feeding device, fluctuations in the flow rate of the electrode compound that is passed on from the mixing device to the feeding device being evened out.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a method and an apparatus for manufacturing an electrode for a rechargeable battery according to the preamble of the independent claim.

Background Art

[0002] Common to this type of method is that, in order to manufacture an electrode, first an electrode material is applied to a carrier. This application of the electrode material is then further processed by downstream method steps, particularly drying steps, extraction steps, and / or steps for introducing a suitable electrolyte, depending on how the subsequent method proceeds, to form the electrode. The electrode material may consist of a plurality of components. Here, the application of the electrode material to the carrier is not a trivial step but a step that relates to the quality of the resulting rechargeable battery. In the finished rechargeable battery, the carrier, which can in particular be a metal foil, is often wound, folded and / or laminated into a plurality of layers. Therefore, the thin layer of electrode material has to be applied with high uniformity.

[0003] On an industrial scale, this is carried out by the so-called "wet method". The wet method includes the step of mixing substances that already have a very low viscosity at a relatively low temperature. The substance is then applied to the carrier at room temperature, generally by means of a slot die.

[0004] The drawback of these methods is that the required viscosity of the substance to be coated is determined by the solvent. The solvent can be, for example, N-methyl-2-pyrrolidone (NMP). The resulting substance, known as a slurry, has excellent properties for coating carriers, but the solvent must then be removed from the electrode material. The use of solvents creates environmental and health hazards, which are undesirable. Therefore, especially in the context of increasingly stringent environmental regulations, it is desirable to find ways to eliminate, or at least reduce, the need to use such harmful solvents.

[0005] Therefore, for example, Patent Document 1 (DE102004012476A1) discloses a method for producing an electrode material using a flow accelerator at high temperature with minimal solvent use and for coating it onto a carrier. This method is carried out using a so-called twin-screw extruder, which is heat-retaining and has a very high shear rate. As a result, this extruder can achieve sufficient mixing even with relatively viscous materials. Thus, when the components of the electrode material are supplied to this extruder, such a twin-screw extruder can first process these components to make a sufficiently homogeneous mixture, and then feed this material through an equally heat-retaining extrusion die, thereby coating the material onto a carrier.

[0006] However, in reality, the mass flow of electrode material delivered by a twin-screw extruder is known to fluctuate over time. This is due to the type of structure of the twin-screw extruder, which acts as a mixing and feeding device in this process. This fluctuation results in a lack of uniformity when coating the electrode material onto the carrier, which has so far hindered the application of this method on an industrial scale.

[0007] Similarly, Patent Document 2 (EP2744019A1) discloses a method for manufacturing electrodes that avoids harmful solvents to the greatest extent possible. However, in this method, a molding material is first produced in the form of extruded pellets. In a further method step, these pellets are melted at a later point and applied to a carrier by extrusion. Implementing the method in this manner is inefficient. On the one hand, repeated melting of the electrode material increases energy consumption. On the other hand, separating the production of pellets mixed with the electrode material from the subsequent application of the electrode material to the carrier creates additional effort regarding pellet handling between the two method steps. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] DE102004012476A1 [Patent Document 2] EP2744019A1 [Overview of the project]

[0009] Therefore, the present invention is based on the objective of providing a method and apparatus for manufacturing electrodes for rechargeable batteries that can uniformly coat an electrode material onto a carrier with as little use as possible and are more efficient.

[0010] This objective is achieved by a method and apparatus having the features of the independent claim. The features of the dependent claim relate to advantageous embodiments.

[0011] A method for manufacturing electrodes for rechargeable batteries includes, first, mixing electrode material in a mixing device and then feeding it through the mixing device to a supply device. In this case, the mixing device and / or supply device operate in particular continuously. The feeding of the mass flow of electrode material through the mixing device to the supply device is carried out in particular continuously. In this case, fluctuations in the mass flow of electrode material fed through the mixing device to the supply device are compensated for. The feeding of the mass flow of electrode material through the mixing device to the supply device allows this method to be carried out without interruption. This has the advantage, on the one hand, of making the method more efficient as a result of no longer needing storage and reduced handling effort, and on the other hand, of better ensuring certain characteristics, in particular certain quality, compared to the “wet method” described in the prior art in which the production of “slurry” is carried out in batches and therefore discontinuously, and to implementations that first produce intermediate products such as pellets as described at the beginning, and on the other hand, of better ensuring certain characteristics, in particular certain quality.

[0012] By implementing the method in this way, the step of mixing the electrode material and the step of supplying it through the extrusion die can be separated from each other. As a result, the supply device can be optimized to the extent that it can supply the most constant mass flow possible through the extrusion die. This, in turn, leads to the electrode material being uniformly coated onto the carrier.

[0013] Accordingly, the apparatus presented and described includes a compensation device for compensating for fluctuations in the mass flow of electrode material produced by a mixing device and supplied to a feeding device.

[0014] By separating the function of "mixing electrode material" and the function of "supplying electrode material via extrusion die" into different directional steps or different technical devices, the effect is achieved that each device or each method step can be optimized with respect to the effect to be achieved. The electrode material mixing or mixing device can be optimized with respect to mixing the components as well as possible, and correspondingly with respect to the homogeneous electrode material obtained. On the other hand, the supply of electrode material via extrusion die, or the supply device used therefor, can be optimized with respect to keeping the mass flow of the supplied electrode material as constant as possible. The extrusion die can be a slot die in particular.

[0015] Thus, to compensate for fluctuations, the electrode material may be stored in an intermediate location. For this purpose, the apparatus may have, for example, an intermediate storage device. The intermediate storage device may be, for example, a compensation container. In particular, the intermediate storage device allows the mixing device to supply a mass flow that fluctuates over time to the intermediate storage device, while at the same time the supply device receives a constant mass flow that fluctuates at least less than the mass flow generated by the mixing device. Thus, fluctuations in the mass flow delivered by the mixing device are compensated for by corresponding fluctuations in the filling level of the intermediate storage device. Here, it has been found that in practice the intermediate storage device may be of relatively small size. This is always true, in particular, when the overall mass flow of the electrode material delivered by the mixing device fluctuates little, and / or when these fluctuations occur regularly, especially periodically. Both of these cases are always true, for example, when the mixing device is a twin-screw extruder.

[0016] Alternatively and / or additionally, to compensate for variations in the mass flow of electrode material delivered by the mixing device, the electrode material may be returned to the mixing device. For the apparatus, this specifically means that the apparatus has a return device for returning the electrode material to the mixing device.

[0017] This has the effect of branching off a portion of the fluctuating mass flow of electrode material delivered by the mixing device. This portion of the flow is returned to the mixing device, where it is mixed with the starting materials of the electrode material. In particular, if the mixing ratio of each component is kept constant over time, the returned electrode material does not change the quality, especially the composition, of the resulting mixture. In this case, the returned portion of the electrode material flow has fluctuations corresponding to those resulting from the fluctuations in the mass flow of electrode material delivered by the mixing device. Correspondingly, the remainder of the mass flow of electrode material delivered by the mixing device becomes stable or at least less fluctuating than the mass flow delivered by the mixing device. Thus, the supply device can receive a constant mass flow of electrode material, or at least a more constant mass flow than the mass flow delivered by the mixing device.

[0018] Incidentally, it is particularly preferable if the mixing device and the supply device are designed and / or operate in such a way that the mixing device delivers a mass flow of electrode material greater than the amount the supply device receives. This difference makes it possible to divert some of the flow that needs to be returned.

[0019] Needless to say, the two concepts presented above for providing compensation and compensation devices may be implemented in the same method or apparatus. This means that this method may provide both the intermediate storage of electrode material between mixing and feeding through an extrusion die, and at the same time, the return of electrode material. Accordingly, the apparatus may have both a return device and an intermediate storage device positioned between the mixing device and the feeding device. Positioning between the feeding device and the mixing device does not necessarily mean the spatial arrangement of the devices relative to each other, but rather their arrangement along the flow path of the electrode material.

[0020] The method may include coating the electrode material onto a carrier in the form of an uninterrupted strip at least 2 m long, and especially at least 5 m long, extending in the coating direction. Compensating for fluctuations in the mass flow of the electrode material delivered to the supply device by the mixing device has the effect of enabling uniform coating even on such long strips of electrode material. Coating uniformity here specifically corresponds to forming the edges of the electrode material extending parallel to the coating direction as straight as possible. The coating direction should be understood in particular as the direction in which the carrier moves through the extrusion die while the electrode material is being coated. Relative movement has the effect of causing the strip of electrode material to accumulate on the carrier in this coating direction.

[0021] The method may include, in particular, coating the carrier with the electrode material such that strips without electrode material, extending parallel to the coating direction of the electrode material, are formed on the carrier along the electrode material. Such strips without electrode material may function, for example, for electrical contact between the respective electrodes. Incidentally, it is especially important that the electrode material extending parallel to the coating direction has clearly defined and as straight as possible edges. Only in this way is it ensured that strips without electrode material, with clearly defined boundaries, are formed on the carrier.

[0022] The apparatus may have a measuring device for measuring a variable relating to the electrode material being delivered to the supply device by the mixing device. Correspondingly, the method may include measuring a variable relating to the electrode material being delivered to the supply device by the mixing device. The variable may be, in particular, the filling level of the intermediate storage device and / or the mass flow of the electrode material returned by the return device. As a result, information can be obtained, in particular, about the degree to which the coordination between the mixing device and the supply device is coordinated with respect to the mass flow of the electrode material being processed by each, in particular, about the extent to which continuous operation is possible, and / or about whether the electrode material is accumulating or depleted in the intermediate storage device or in the circuit formed by the return. This is especially true when the mass flows delivered by the mixing device and / or received by the supply device are not sufficiently coordinated with each other.

[0023] With regard to the methods and apparatus described herein, and especially with respect to the measurements described above, mass flow is not necessarily understood to mean that the actual (molar) amount of substance is recorded or measured. Rather, mass flow should be understood as mass flow in its broadest sense, that is, mass flow represented by appropriate representative variables, such as mass flow and / or volume flow as the measured and / or controlled variables actually used.

[0024] In particular, the device may be controlled in response to the measured variable. For this purpose, the device may have a closed-loop and / or open-loop control device configured accordingly. This may include closed-loop control, which functions particularly to maintain a steady state in continuous operation. In particular, for this purpose, the closed-loop and / or open-loop control device may function to perform closed-loop and / or open-loop control of a metering device for metering the components of the electrode material. Incidentally, the metering device may be suitable for metering a plurality of components, or there may be a plurality of metering devices. The metering device functions particularly to send one or more components of the electrode material to a mixing device. Such a metering device may mainly function to set the quantitative ratio of the individual components of the electrode material. However, further, the mass flow of the total amount of the plurality of components sent to the mixing device may also be controlled in an open-loop and / or closed-loop manner. Thus, in combination with the above-described measurement or measuring device, it is possible to ensure that the filling level of the intermediate storage device and / or the mass flow of the electrode material returned by the return device vary within a tolerance range particularly suitable for stable, continuous and sustained operation.

[0025] In particular, the method may include that the electrode material is kept in a fluid state from the time it exits the mixing device until it enters the supply device. This particularly corresponds to the period during which the electrode material is stored intermediate, or the point at which a part of its flow is branched off to return the electrode material to the mixing device. By keeping the material in a fluid state, it becomes possible to perform this process stably and continuously.

[0026] The method may include degassing the electrode material. This may be desirable especially to ensure that no gas is contained in the electrode material after it has been applied to the carrier. The inclusion of such gas may occur, for example, during the mixing of the components of the electrode material. Similarly, the inclusion of gas may occur due to the evaporation of impurities. These impurities can be, for example, water. Degassing may already be carried out especially during the mixing of the components of the electrode material and / or during the intermediate storage of the electrode material.

[0027] In particular, the method includes that the temperature of the electrode material, from exiting the mixing device until entering the supply device, is always at least 80 °C, especially at least 90 °C, and / or at most 160 °C, especially at most 120 °C. This relates especially to the temperature of the electrode material during intermediate storage and / or the temperature of the electrode material in a partial flow branch for returning to the mixing device.

[0028] In particular, the method includes that the temperature of the electrode material in the mixing device is at least 80 °C, especially at least 90 °C, and / or at most 140 °C, especially at most 120 °C.

[0029] In particular, the method includes that the temperature of the electrode material in the supply device and / or in the extrusion die is at least 80 °C, especially at least 90 °C, and / or at most 150 °C, especially at most 130 °C.

[0030] Within these temperature ranges, appropriate rheological properties can be achieved, and it has been found that especially the electrode material can be kept in a fluid state.

[0031] The apparatus may have a heating device, which in particular serves to heat the mixing device, compensation device, feeding device, and / or extrusion die. The heating device, in particular, enables the electrode material to remain fluid from the time it is mixed in the mixing device until it exits the extrusion die. Accordingly, the heating of the electrode material achieved in this manner is performed in particular from the time the electrode material is mixed until it exits the extrusion die.

[0032] This mixing device, especially one operating continuously, can be a multi-screw extruder. Because multi-screw extruders generate high shear rates in the material supplied through them, they have excellent properties for mixing viscous or paste-like materials. Therefore, when multi-screw extruders are used as mixing devices, they result in very good homogeneity of the electrode material produced. Incidentally, it has been proven particularly advantageous if the mixing device is a twin-screw extruder.

[0033] The supply device is, in particular, a positive displacement pump. Positive displacement pumps are particularly advantageous in supplying relatively viscous media. In particular, the supply device may be a gear pump. Gear pumps have been shown to be particularly capable of producing a very consistent mass flow.

[0034] In particular, because shear forces are dominant within the extrusion die, the fluid properties of the electrode material are selected in conjunction with the characteristics of the method and / or apparatus such that the electrode material has fluidity within the extrusion die and loses this fluidity as soon as it leaves the extrusion die, and thereafter the shear force disappears. This has a favorable effect on the electrode material, which maintains a cross-section predetermined by the shape of the extrusion die when it is applied to the carrier.

[0035] The electrode material may have a main component and a plasticizer as its basic components. In this case, in particular, the main component includes components that form the electrode after at least partially removing the plasticizer. The electrode material, in particular the main component, has an active material as a component. The active material may be graphite in particular in the case of the negative electrode, and / or lithium nickel manganese cobalt oxide, lithium nickel cobalt aluminum oxide, or lithium iron phosphate (LiFePO4) in the case of the positive electrode. Other active materials, in particular lithium compounds, are also possible. What is called the active material is a chemically active substance in the electrode that is responsible for storing energy, and these active substances undergo chemical changes, including the release and / or storage of charge carriers, when the rechargeable battery is charged and / or discharged.

[0036] The mass ratio of the active material in the main component is at least 88% and / or at most 97%.

[0037] The electrode material, particularly the main component, may also include additives to improve conductivity. These additives may be, for example, carbon black and / or graphite. The mass ratio of the additives in the main component is at least 1.5% and / or at most 5%.

[0038] The electrode material, particularly the main component, may contain a binder. The binder may be a polymer, particularly a fluoropolymer. The mass ratio of the binder in the main component may be at least 1.5%, particularly at least 3%, and / or at most 7%, particularly at most 5%.

[0039] The electrode material may also contain a plasticizer. The plasticizer can be, for example, a substance having appropriate phase transition behavior. This should be understood to mean a substance with a melting point of at most 80°C, particularly at most 35°C, and / or a boiling point of at least 120°C, particularly at least 140°C. A substance having such phase transition behavior is suitable for keeping the electrode material plastic or fluid during mixing or supply to the extrusion die, and at the same time, for ensuring the formation of a stable layer on the carrier immediately after exiting the extrusion die without the risk of gas formation, especially during method steps carried out at high temperatures.

[0040] The mass ratio of the plasticizer may be selected in particular depending on the properties of the main component. Parameters such as particle size, surface size, and quantity and type of additional materials, such as binders and / or additives to improve conductivity, may be considered here. Similarly, the quantity and type of active material also have an effect. Incidentally, when graphite is used as the active material for the negative electrode, it has been proven advantageous if the mass ratio of the plasticizer is at least 14%, particularly at least 20%, and / or at most 42%, particularly up to 40%. For the positive electrode, particularly in the case of a lithium iron phosphate positive electrode, the ratio of the plasticizer can be at least 30%, particularly at least 35%, and / or at most 50%, particularly up to 42%.

[0041] In particular, the plasticizer can be ethylene carbonate. According to prior art, ethylene carbonate has already been used as an electrolyte in rechargeable batteries of that type, and therefore does not pose a problem for rechargeable batteries, especially in terms of how they function. Furthermore, due to the location of its melting point, ethylene carbonate exhibits temperature-dependent behavior, which allows it to act as a plasticizer at the temperature that spreads between the mixing device and the extrusion die, and to eliminate, at least to a considerable extent, its effect as a plasticizer after the electrode material has cooled on the carrier, especially after it has cooled to room temperature.

[0042] The method may include cooling the electrode material after it has been applied to the carrier. This may particularly include cooling it to room temperature.

[0043] The carrier can be a metal foil, in particular. The metal foil can take the form of an elongated strip. While the electrode material is being applied to the carrier, the metal foil is moved, in particular, through an extrusion die. The metal can be copper and / or aluminum, in particular. The carrier may be stored, in particular, on rollers, from which it is unfolded and conveyed toward the extrusion die.

[0044] A measuring device may be provided to record the amount of electrode material coated onto the carrier. This device may be, in particular, a measuring device for measuring the thickness of the electrode material coated onto the carrier. In particular, the measuring device may be a so-called "beta gauge." This is a measuring device for measuring thickness using radiation, and this device measures the thickness of the transradiated layer based on beta rays. However, in principle, other methods of thickness measurement, especially methods of thickness measurement using other types of radiation, are also conceivable.

[0045] The apparatus may have a control device configured to control the apparatus, particularly the supply device, in accordance with the measured values ​​recorded by the measuring device. As a result, fluctuations in the mass flow of the electrode material can be further reduced.

[0046] The method may include removing plasticizer from the electrode material to at least a considerable extent. This may particularly include forming pores in the electrode. The removal of plasticizer may be carried out in particular by the action of heat. For this purpose, the apparatus may have a heating device in particular. This heating device may be, for example, an infrared heating device. In this case, the action of heat may particularly have the effect of evaporating the plasticizer.

[0047] The plasticizer can be reused. This can be done, for example, by first removing the plasticizer with a gas flow if it has already evaporated, and then removing it from the gas flow by condensation. The gas flow can be an air flow in particular.

[0048] According to the method described above, the electrode material can be coated on both sides of the carrier material.

[0049] Further practical embodiments and advantages of the present invention are described below with reference to the drawings. [Brief explanation of the drawing]

[0050] [Figure 1] This is a schematic diagram showing the first part of the apparatus for manufacturing electrodes. [Figure 2] This figure shows a second part of the apparatus for manufacturing electrodes, which works in conjunction with the part shown in Figure 1. [Figure 3] This is a plan view showing a portion of a strip of electrode material coated onto a carrier. [Modes for carrying out the invention]

[0051] The apparatus 10 provided as an example is suitable and intended for carrying out a method in which an electrode material 12 is applied to a carrier 14. The carrier 14 may be in the form of a strip or a wound form, as in the example presented. Correspondingly, the apparatus 10 may have a dispensing device 16 for dispensing the carrier 14.

[0052] The electrode material 12 is applied to the carrier 14 by an extrusion die 18. For this purpose, the electrode material 12 is supplied through the extrusion die 18 by a supply device 20. In the example shown, the supply device 20 may be a gear pump, although it is only schematically illustrated. In this case, the carrier 14 is moved in the application direction 44 so as to pass through the extrusion die 18.

[0053] Apparatus 10 also includes a mixing device 22. Although only schematically illustrated in the example shown, the mixing device 22 may be formed as a twin-screw extruder. The mixing device 22 mixes the electrode material 12, and this electrode material 12 is then sent to the supply device 20 by the mixing device 22. In this case, fluctuations in the mass flow of the electrode material 12 sent from the mixing device 22 to the supply device 20 are compensated by a compensation device 24. In the example shown, the compensation device 24 can be an intermediate storage device. The compensation device 24 can store a portion of the mass flow of the electrode material 12 sent to the supply device 20 by the mixing device 22 in the intermediate location. The fluctuations in the mass flow are, so to speak, "smoothed out".

[0054] As shown in the example, the apparatus 10 may have a plurality of weighing devices 26, 28 for weighing various components of the electrode material 12. Similarly, the apparatus 10 may have a weighing device 30 for weighing plasticizers. Using the weighing devices 26, 28, 30, the corresponding components can be weighed each time and fed into the mixing device 22, that is, the mass flow can be controlled in an open-loop and / or closed-loop manner. The apparatus 10 may have a closed-loop and / or open-loop control 32 specifically designed to control the mass flow sent to the mixing device 22 by the weighing devices 26, 28, 30 according to a measuring device, the measuring device is not described further. The measuring device not described further may be, in particular, a measuring device for measuring the filling level in the intermediate storage device.

[0055] The mixing device 22, the compensation device 24, the supply device 20, and / or the extrusion die 18 may each have a heating device 34. In particular, the mixing device 22 may have multiple heating devices 34, as shown in the example of the apparatus 10 provided as an example. Thus, different heating zones can be realized, for example.

[0056] As in the example apparatus 10, the carrier 14 may be supplied to the cooling device 36 immediately after the electrode material 12 is applied to it. Incidentally, the change from Figure 1 to Figure 2 is simply for practical representational reasons. In fact, the composite material, including the carrier 14 and the electrode material 12, formed by the application, is directly subsequently transported between the partial apparatus 10 shown in Figures 1 and 2.

[0057] As shown in the example, the composite material thus formed, including the carrier 14 and the electrode material 12, may be supplied to the layered measuring device 38. The results of the layer thickness measurement, in particular the results of the layer thickness measurement of the electrode material 12 layer, may also be used with respect to the closed-loop and / or open-loop control of the apparatus 10, in particular the weighing devices 26, 28, and / or 30.

[0058] As in the example provided, the apparatus 10 may have a heating device 40. This heating device 40 can be, for example, an infrared oven. This heating device, in particular, serves the function of removing plasticizer from the electrode material 12, at least partially. This heating device 40 also has the effect of creating pores, into which electrolytes can be introduced at a later time.

[0059] As shown in the example, the apparatus 10 may have a winding device 42 for winding up an electrode formed of a composite material including a carrier 14 and a layer of electrode material 12 coated thereon.

[0060] Figure 3 shows a portion of the carrier 14 coated with strips of electrode material 12. The strips of electrode material 12 extend parallel to the coating direction 44. Strips 46 without electrode material also extend parallel to the strips of electrode material 12 and the coating direction 44. As a result of compensating for fluctuations in the mass flow delivered to the supply device by the mixing device, the edges 48 are formed particularly straight and regularly.

[0061] According to the first example, the electrode material for the positive electrode mixed in the mixing device can be a mixture of a main component and a plasticizer. The mass ratio of the plasticizer in this mixture can be, for example, 24%. The plasticizer can be ethylene carbonate. The main component may contain two different binders in mass ratios of 4% and 2% relative to the main component, graphite and carbon black as additives to enhance conductivity, each in mass ratio of 3%, and lithium nickel cobalt aluminum oxide as the active material in mass ratio of 88%.

[0062] According to the second example, the electrode material for the positive electrode mixed in the mixed device can be a mixture of a main component and a plasticizer. The mass ratio of the plasticizer in this mixture can be, for example, 35%. The plasticizer can be ethylene carbonate. The main component may contain a binder at a mass ratio of 7% relative to the main component, carbon black at a mass ratio of 5% as an additive to enhance conductivity, and lithium iron phosphate at a mass ratio of 88% as an active material.

[0063] According to the third example, the electrode material for the negative electrode mixed in the mixing device can be a mixture of a main component and a plasticizer. The mass ratio of the plasticizer in this mixture can be, for example, 38%. The plasticizer can be ethylene carbonate. The main component may contain a binder at a mass ratio of 6.5% relative to the main component, carbon black at a mass ratio of 4.5% as an additive to enhance conductivity, and graphite at a mass ratio of 89% as an active material.

[0064] The features of the present invention disclosed herein, in the drawings and in the claims may be fundamental to realizing the invention in its various embodiments, individually and in any desired combination. The present invention is not limited to the embodiments described. The present invention can be modified within the scope of the claims, taking into account the knowledge of those skilled in the art. [Explanation of Symbols]

[0065] 10 equipment 12 Electrode materials 14 Carriers 16. Dispensing device 18 extrusion dies 20 supply devices 22 Mixing devices 24 Compensation devices 26 Weighing devices 28 Weighing devices 30 weighing devices 32. Closed-loop / open-loop control 34 Heating devices 36 Cooling Devices 38-layer thickness measuring device 40 Heating devices 42 Rewinding device 44. Application direction 46 Strips without electrode material 48 Edge

Claims

1. An apparatus (10) for manufacturing electrodes for rechargeable batteries, comprising a mixing device (20) for mixing electrode material (12) and a supply device (20) for supplying the electrode material (12) via an extrusion die (18), The device includes a compensation device (24) for compensating for fluctuations in the mass flow of the electrode material (12) produced by the mixing device (22) and sent to the supply device (20), The device includes a measuring device (38) for measuring a measurement variable related to the electrode material (12) that is sent to the supply device (20) by the mixing device (22), The apparatus is characterized in that the compensation device (24) has a return device for returning the electrode material (12) from between the mixing device (22) and the supply device (20) back to the mixing device (22).

2. The apparatus according to claim 1, characterized in that the mixing device (22) is a multi-screw extruder or a twin-screw extruder.

3. The apparatus according to claim 1 or 2, characterized in that the supply device (20) is a positive displacement pump or a gear pump.

4. The apparatus according to claim 1, characterized in that it has a closed-loop and / or open-loop control device (32) for controlling a weighing device (26, 28, 30) for weighing the components of the electrode material (12) according to the measured variable.

5. An apparatus (10) for manufacturing electrodes for rechargeable batteries, comprising a mixing device (20) for mixing electrode material (12) and a supply device (20) for supplying the electrode material (12) via an extrusion die (18), The device includes a compensation device (24) for compensating for fluctuations in the mass flow of the electrode material (12) produced by the mixing device (22) and sent to the supply device (20), The apparatus is characterized in that the compensation device (24) has a return device for returning the electrode material (12) from between the mixing device (22) and the supply device (20) back to the mixing device (22), and a measuring device for measuring the mass flow returned by the return device.

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