Method for preparing an electrode mixture, and apparatus therefor.

Abstract

A process for producing an electrode mixture from various substances, namely an active material with a mass fraction w1, an additive with a mass fraction w2 optionally, and a binder with a mass fraction w3, where w1 and w3 are each greater than 0%, w2 is greater than or equal to 0%, and w1, w2, and w3 are each less than 100%, as follows 1) A step of filling the container with the active material, a first percentage p of the additive a1 , and / or a first percentage p of the binder b1 , comprising the step of [Equation 1] TIFF2026516873000019.tif4161 and [Equation 2] TIFF2026516873000020.tif4161, but [Equation 3] TIFF2026516873000021.tif4161 or [Equation 4] TIFF2026516873000022.tif4161, any one of which is the step of A) A step of introducing a first mechanical power P1 into the substances contained in the container by shear force or impact force 2) A step of filling the container with a second percentage p of the additive a2 and / or a further percentage p of the binder b2 , comprising the step of [Equation 5] TIFF2026516873000023.tif4161 and [Equation 6] TIFF2026516873000024.tif4161, which is the step of B) A step of introducing a second mechanical power P2 into the substances contained in the container by shear force or impact force during a second time interval T2 to generate a second mixture, where P2 > P1 comprising W) Repeating steps A) and B) and performing step K) between steps A) and B) as long as the binder and any of the additives are not fully incorporated K) Further percentage p of the additive ak and / or a further percentage p of the binder bk The following is introduced into the container, with k=3 in the first iteration, and k is increased by 1 after each iteration. [Number 7] TIFF2026516873000025.tif13161 and [Number 8] The filename is TIFF2026516873000026.tif13161. process.

Description

[Technical Field]

[0001] The present invention relates to a method for preparing an electrode mixture, an apparatus for carrying out the method, the use of the apparatus for carrying out the method, and an electrode mixture produced according to the method. [Background technology]

[0002] In recent years, the focus has shifted to battery technology, particularly lithium-ion technology. This is because it is essential not only for the functionality of pure electric vehicles, but also for stationary energy storage systems. Long-lasting, high-capacity batteries that can be manufactured cost-effectively are a prerequisite for the acceptance of pure electric vehicles.

[0003] Lithium-ion batteries are currently the primary type of battery in use.

[0004] A typical lithium-ion cell electrode has a copper foil that functions as the anode and an aluminum foil that functions as the cathode. Typically, the foil is coated on both sides with an active material, and at least in the case of a cathode, it is also coated with an additive.

[0005] During charging of a lithium-ion cell, lithium ions move from the cathode to the anode via the electrolyte and are held there by particles of the active material. Because the process described is reversible, when the battery discharges, a lithium-ion current flows from the anode to the cathode.

[0006] High demands are placed on the electrodes in order to manufacture high-capacity and reliable lithium-ion batteries.

[0007] The electrode layer must have pores through which the electrolyte can penetrate to transport lithium ions to all particles of the active material. Ideally, the active material should be covered with the electrolyte over as large an area as possible. Furthermore, to ensure that electrons are reliably transported to and from each particle of the active material, the particles of the active material must be electrically connected to a metal foil, i.e., copper foil or aluminum foil in the example described.

[0008] Furthermore, the active material particles must be bonded both to each other and to the metal foil, for which a binder material is used. Finally, the layer thickness should be as uniform as possible.

[0009] To produce the layer, the starting materials, i.e., the active material, binder, and any additives, must be mixed and dispersed together to form a so-called "slurry." Typically, a liquid solvent (e.g., water or N-methyl-2-pyrrolidone (NMP)) is added at this stage, but this must be removed again in a complex drying process after the electrode mixture has been applied to the film.

[0010] This process is time-consuming and consumes a large amount of energy. Furthermore, the mechanical production of electrode mixtures requires large-scale drying equipment. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] Therefore, based on the prior art described above, the object of the present invention is to provide a method for preparing an electrode mixture that reduces the amount of solvent required, or in the best case, operates completely solvent-free, and still provides a high-quality electrode mixture that is easy to process.

[0012] Furthermore, an object of the present invention is to provide an apparatus for carrying out this method. [Means for solving the problem]

[0013] Regarding a method, the object is a method for preparing an electrode mixture from various substances, that is, an active material with a mass fraction w1, an additive with a mass fraction w2 optionally, and a binder with a mass fraction w3, where w1 and w3 are each greater than 0%, w2 is 0% or more, and w1, w2, and w3 are each less than 100%. The method is as follows 1) A step of filling a container with an active material, a first percentage p of an additive a1 , and / or a first percentage p of a binder b1 , where

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[0014] When electrode mixtures are manufactured for use as cathodes, for example, lithium nickel-cobalt manganese oxide, lithium manganese oxide, lithium cobalt oxide, lithium nickel-cobalt aluminate, lithium iron phosphate, or other lithium or sodium metal oxides can be used as active materials.

[0015] When the electrode mixture is prepared for use as an anode, for example, carbon such as graphite, activated carbon, or graphene, or silicon-carbon composites can be used as the active material. The mass fraction w1 can be up to 99.9%, and w1 is preferably 90% to 99.9%.

[0016] The additives used are mainly conductive additives, such as conductive carbon black, which are particularly necessary in the manufacture of electrode mixtures for the cathode because the electrical conductivity of the active material is often low. In addition to conductive additives, electrode mixtures for the anode and cathode may use, for example, silicon or silicon compounds, solid electrolytes, nanoparticle aerosols, oxalic acid, graphene, carbon nanotubes (CNTs), styrene-butadiene rubber (SBR), or conductive graphite, with a mass fraction w2 preferably between 0% and 10%. In particular, in the case of silicon or silicon compounds or solid electrolytes, the mass fraction may significantly exceed 10%.

[0017] The mass fraction w3 of the binder is also 0.1% to 10% in preferred embodiments. In particular, polymeric binders such as fluorine-containing polymer binders such as PVDF and PTFE are used as binders. Alternatively, carboxymethylcellulose (CMC) can also be used as a binder. Many polymer binders, especially PTFE, exhibit a fibrillation effect when energy, particularly shear energy, is applied at certain temperatures, thereby improving the usability of the electrode mixture.

[0018] Process A) can be carried out simultaneously with or after process 1).

[0019] In step A), the raw materials added to the container in step 1) are mixed dry. That is, no solvent such as water is added. This produces a mostly homogeneous mixture. A particle composite structure is formed. That is, the active material particles are surrounded by a binder and / or (conductive) additive.

[0020] After step A), step 2) is performed, in which further proportions of additives and / or binders are introduced. It is not always necessary to introduce further proportions in step 2). For example, if all proportions for step B) have already been introduced in step 1), then it is not necessary to introduce further proportions in step 2). Therefore, proportion pa2 and p b2 Both can be 0%. In other words, step 2) can be omitted.

[0021] Step B) can be carried out either after or during Step 2), in which a second mechanical power P2 is introduced into the mixture by shear force, although an impact force may be used instead, and this P2 is greater than the first mechanical power.

[0022] Mechanical power can be introduced in both process A) and process B), for example, using a well-designed mixing tool in a mixing vessel. In process B), the speed increases compared to the speed in process A). The mechanical outputs P1 and P2 do not need to be constant and can change during the execution of each process. For example, the speed of the mixing tool used can be kept constant throughout each process, but the power input also changes because the density and fluidity of the mixture change during each process. However, it is essential that the mechanical power introduced in process B) is greater than that in process A).

[0023] Alternatively, mechanical power (or mechanical force) may be introduced in a continuous extruder. In this case, different mechanical powers in consecutive time intervals can be achieved by using zones of different lengths along the mixing axis of the extruder and using different shapes of mixing components in each zone.

[0024] For example, the PTFE binder initially exists as aggregates of individual, bead-like polymer fiber particles. In step B), the polymeric binder components adhere to the surface of the active material, forming filamentous / fibrous structures that form a network, usually a spiderweb-like network, into which the previously formed particle composite structures are incorporated. In other words, the active material is coated with the binder, and possibly additives.

[0025] Depending on the application, the time interval T2 of process B) may be 1 minute to 90 minutes, and the duration is preferably 10 minutes to 30 minutes.

[0026] If all the desired components of the electrode mixture to be produced have already been added before performing step B), the method according to the invention can end here. However, if not all of the binder and, where applicable, all of the additives have been completely added, steps A) and B) are repeated and a further part of the additives and / or binder is added before step A) in the repetition and / or between step A) and step B). Thus, the part of the binder and / or additives added later also passes through steps A) and B).

[0027] In a preferred embodiment, especially in the production of the electrode mixture for the cathode, it is specified that w2 > 0%, p a1 > 0%, and p b1 = 0%. In other words, in step 1), only part or all of the additives are added and no binder is added. The binder is added only in step 2) or step K) when steps A) and B) are repeated.

[0028] In a further preferred embodiment, at least during the last execution of step B), preferably during all executions of step B), the power P2 is such that the temperature of the substance taken into the container rises in step B), and step B) ends immediately when the temperature of the substance taken into the container reaches a predetermined temperature T H .

[0029] T H is preferably T H > 50 °C, particularly preferably 50 °C < T H < 80 °C, most preferably 50 °C < T H < 70 °C. The temperature T H should not be significantly exceeded.

[0030] Polymer binders, especially PTFE binders, usually show fibrillation only at significantly high temperatures. However, surprisingly, fibrillation is already achieved at lower temperatures by the introduction of mechanical energy.

[0031] In a specific application, because the temperature T is reached very quickly, if the time interval during which step B) is carried out is excessively short, the time interval can be extended by cooling the container. H In a specific application, because the temperature T is reached very quickly, if the time interval during which step B) is carried out is excessively short, the time interval can be extended by cooling the container.

[0032] In a further preferred embodiment, the following is carried out following the last execution of step B). Step C) A step of introducing a third mechanical power P3 into the substance contained in the container by a shearing force or an impact force during a time interval T3, where the shearing force is preferred and P3 < P2.

[0033] If the shearing force is introduced into the mixture via a mixing tool, the speed of the mixing tool can be reduced in step C).

[0034] In order to form an optimally structured dry mixture, the input of mechanical power can be reduced in step C), and surprisingly, the quality of the mixture is improved thereby. It has been found that a large mechanical power P2 only needs to be initially applied to form a network-like structure. As soon as the fibrillation of the binder starts, the complete formation of the structure can also be completed with a smaller power input.

[0035] Generally, it is advantageous if the time interval T3 is shorter than the time interval T2.

[0036] In a preferred embodiment, all or at least 80% of the energy required in step B) to raise the temperature to a predetermined temperature T H is supplied by mechanical energy, i.e., by a shearing force.

[0037] Additional external heating is not necessarily required.

[0038] Temperature T H is reached, or the temperature T HAs soon as it exceeds, the mechanical power introduced into the mixture is reduced so that no significant further increase in temperature occurs.

[0039] Essentially, the temperature of the mixture is kept constant and the mixture is simply stirred. This completes the fibrillation process and produces a so-called structured dry mixture, which is well-suited for manufacturing electrodes.

[0040] In a preferred embodiment, in step C), the temperature of the substance contained in the vessel is between 0.8×T H and 1.1×T H and preferably between 0.9×T H and 1.05×T H and the power is adjusted to be maintained between.

[0041] In a further preferred embodiment, after the last execution of step B) and, if present, after step C), the following steps are carried out. D) Cooling the substance contained in the vessel to temperature T L <T H while introducing a fourth mechanical power P4 into the substance in the vessel by shear force, where P4 < P2 and preferably P4 < P3.

[0042] This means that at the end of step C), while the mixture is cooled, the mixture is simultaneously continuously stirred to ensure good mixing. In principle, it is also possible to cool the non-moving mixture in a stationary state such that P4 = 0. It is also possible to intermittently move or stop the mixture during cooling. Temperature T L is preferably less than 45°C, particularly preferably less than 40°C, and most preferably less than 35°C.

[0043] Moving the mixture during cooling significantly changes the structure, i.e., the performance of the electrode mixture during transportation and distribution.

[0044] Cooling is advantageously assisted, for example, by cooling the walls of the mixing vessel in which the mixture is held. Alternatively and / or additionally, cooling can be performed by a flow of cold gas and / or using a liquefied gas such as nitrogen or CO2, which may be in the form of dry ice, for example.

[0045] In another preferred embodiment, the following steps are performed after step D). E) A step of crushing a substance contained in a container into a large number of aggregates by introducing a fifth mechanical power P5 such that P5 > P4, wherein the aggregates preferably have an average particle size of 0.05 mm to 5 mm.

[0046] This process ensures that the so-called structured mixture is fine-grained and highly fluid, thus facilitating both removal from the mixing container and supply to subsequent processes for electrode fabrication.

[0047] The method according to the present invention does not require the addition of any solvent.

[0048] The quality of the mixture can be further improved if the process is carried out in a protective gas atmosphere. This is particularly advantageous for process B), but ideally, all steps of the process should be carried out in an inert gas atmosphere. For example, specially prepared dry air or an inert gas can be supplied as the protective gas atmosphere.

[0049] In a preferred embodiment, the electrode is manufactured by rolling the electrode mixture produced according to the method described and laminating it onto a discharge foil, or by pressing it onto a discharge foil.

[0050] The apparatus for carrying out the described method comprises a mixing container having a mixing container wall and a mixing container base, a mixing tool positioned inside the mixing container, and a wall scraper, wherein the mixing tool is rotatable around the tool axis w, the mixing container is rotatable around the container axis b, and the tool axis w and the container axis b are spaced apart from each other.

[0051] Therefore, the apparatus can be used in all process steps. For this reason, both the mixing provided in step A) and the introduction of mechanical energy by shear force in the subsequent steps B) and C) can be carried out within the mixing vessel. In a preferred embodiment, the apparatus includes a heating and / or cooling device for controlling the temperature of the mixed materials placed in the mixing vessel. For example, the mixing vessel can be designed to have a double wall so that a temperature-controlled fluid, i.e., a cooling fluid or a heating fluid, can pass between the two walls of the double wall. In particular, the cooling device can significantly reduce the time required for step C), or limit the temperature of the mixture, and / or the temperature rise in steps A) and / or B), which is a great advantage.

[0052] Furthermore, it is particularly preferable that at least a portion of the base of the mixing container has a double wall, allowing the cooling fluid or heating fluid to pass between the two walls of the double wall.

[0053] Studies have shown that when the mixing tool and mixing container are rotated in the same direction around the tool axis w and container axis b, respectively, during the operation of the apparatus, the quality of the mixture is better. Therefore, when viewing the inside of the mixing container at the base of the container, both the mixing container and the mixing tool are rotating either clockwise or counterclockwise. For other applications, mixing methods are known in which the mixing tool and mixing container are rotated in opposite directions along the tool axis w or container axis b. That is, one element (mixing tool and mixing container) rotates clockwise around its axis, while the other element rotates counterclockwise. However, in the production of electrode mixtures, it has been demonstrated that moving the mixing tool and mixing container in the same direction is effective.

[0054] In a preferred embodiment, the wall scraper is also designed to function as a bottom scraper, thereby preventing the mixed material from permanently adhering to the base of the mixing container, at least in part.

[0055] In a further preferred embodiment, the wall scraper is specified to be in contact with the wall of the mixing vessel and preferably also in contact with the base of the mixing vessel, and / or the mixing tool is specified to be in contact with the base of the mixing vessel. This prevents the formation of a thin film of the electrode mixture on the wall or base. Because direct contact may increase wear on the vessel wall, the base of the vessel, or the wall scraper and mixing tool, in a preferred embodiment, the wall scraper and / or mixing tool are specified to be made of plastic, particularly preferably PTFE or polyamide, at least in the portion that is in contact with the wall of the mixing vessel or the base of the mixing vessel. The mixing tool and / or wall scraper may be made entirely of plastic, or only the portion that is in contact with the wall of the mixing vessel or the base of the mixing vessel may be made of plastic.

[0056] The mixing tool used in the apparatus may be optimized for the production of electrode mixtures. Therefore, in a preferred embodiment, the mixing tool is provided with a tool shaft and at least one mixing section projecting radially beyond the tool shaft, preferably a plurality of mixing sections spaced apart from each other in the axial direction, or the mixing section comprises a shear component positioned within a virtual annulus and a rolling component projecting axially beyond the shear component. For the mixing section, it is particularly preferable to have more than one (e.g., two) rolling components projecting axially beyond the shear component.

[0057] The mixing section may have blade-shaped components oriented radially outward. It is also possible to design the mixing section as a plate with external teeth.

[0058] High machine speeds and, in some cases, abrasive raw material components can cause wear in the mixing area. Therefore, in preferred embodiments, these are specially protected from wear on surfaces that come into contact with the mixture. This can be done for the mixer shaft or fixed wall / bottom scrapers, for example, by spray coating using hard metal or ceramic, or alternatively polyurethane and other plastic materials, especially for the battery electrodes, where copper and zinc-free treatment is required. The surfaces of the mixed parts can also be protected from wear by coating, by manufacturing from ceramic or powder metallurgy materials, or by welding wear-resistant protective parts. Rolling parts projecting axially from shear parts may be made of, for example, ceramic material, or material manufactured by powder metallurgy, such as hard metal, or may have parts made of these materials joined or brazed to steel retaining parts.

[0059] In a further preferred embodiment, a pneumatic conveying device is provided that can transport the mixture out of the mixing vessel. For example, the pneumatic conveying device may be designed as a suction tube, which is located inside or can be located inside the mixing vessel. For example, the suction tube may be incorporated into a wall scraper. Preferably, the suction tube terminates at the radially innermost lower corner of the wall scraper at the bottom of the mixing vessel, or at a corner formed by the mixing vessel and the wall scraper in the flow direction of the mixed material wall.

[0060] In this case, the base of the container does not need to have a discharge port. In particular, the processing in step E) makes the structured dry mixture easily fluid, so that it can be easily removed using a transport device.

[0061] Alternatively, the mixing vessel may have a closable outlet at its bottom, with an air transport line positioned below the outlet so that the mixture exiting the mixing vessel through the outlet falls into the air transport line. Alternatively, a mechanical discharge device such as a belt or vibrating chute, or simply a collection container, may be positioned below the outlet.

[0062] The pneumatic conveying system can be operated with a protective gas, which is preferably transported in a closed circuit. The protective gas supplies dry air, for example, to prevent moisture from being introduced during the process. The air can be specially conditioned to obtain a very low dew point.

[0063] Further advantages, features, and potential applications will become apparent from the following description of preferred embodiments and the associated drawings. [Brief explanation of the drawing]

[0064] [Figure 1] This is a first embodiment of the mixer according to the present invention. [Figure 2] This is a second embodiment of the mixer according to the present invention. [Figure 3] This is a flowchart of the method according to the present invention. [Modes for carrying out the invention]

[0065] Figure 1 shows a first embodiment of the apparatus according to the present invention for carrying out the present method. The apparatus comprises a container having a container wall 1 and a container base 2. The mixing container can be rotated around the container axis b.

[0066] The mixing tool is located inside the mixing container and can be rotated around the mixing tool axis w using a motor 4 and a drive belt 5. The container wall is double-walled and has a partition that divides the cavity formed within the double wall into an inner compartment 6 and an outer compartment 7. A temperature-controlled fluid, for example a cooling fluid in the illustrated embodiment, can be introduced into the inner compartment 6 via a fluid supply unit 8, so that the cooling fluid flows along the base and walls in the direction of the arrow, reaching the outer compartment 7, where it is discharged again. The fluid supply unit 8 is designed here as a rotary feedthrough and handles both the supply and discharge of fluid, transporting the fluid from the stationary part to the rotating part of the container.

[0067] Alternatively, the partition can be omitted. In this case, a return channel should be placed in the outer wall of the double jacket to allow for the discharge of the temperature-controlled fluid.

[0068] By using a temperature-controlled fluid, the container, and consequently the mixture contained within it, can also be heated or cooled. The mixing tool 3 has a plurality of mixing sections 9 and 10. The mixing section 10 is located on the top of the mixing tool 3 and consists of a number of rings arranged parallel to each other, and may have recesses (not shown) on its circumferential surface to increase the applied shear force.

[0069] As shown in the embodiment in Figure 1, the disks denoted by reference numeral 10 may be placed only on the upper part of the mixing tool 3. However, they may be distributed throughout the entire length of the mixing tool 3. In this case, the lower mixing section 9 can be omitted.

[0070] In the embodiment shown in Figure 1, the lower mixing section 9 is also circular, and a series of recesses (not shown) are provided on the circumferential surface of the mixing section 9. The upper rolling component 11 and the lower rolling component 12 extend perpendicularly to the lower mixing section 9. The lower rolling component 12 is in contact with the container base 2, or at least very close to the container base. The distance from the container base should be less than 1 mm. The lower rolling component 12 prevents any part of the mixture from settling on the base. The upper rolling component 11 ensures that the entire mixture moves within the mixer. The upper mixing section 10 may be omitted. In this case, it is advantageous for the upper rolling component 11 to extend further upward to reduce space where mixing or rolling motion does not occur.

[0071] Furthermore, a wall scraper 13 is provided, which is in contact with the container wall 1 and the annular region of the container base 2 to prevent the electrode mixture from adhering to the base region and container wall that are not covered by the lower rolling component 12.

[0072] To remove the finished mixture, the suction tube 14 can be inserted into the mixing container, or the suction tube 14 can be moved back and forth between an upper position where the suction tube is not submerged in the mixture and a lower position where the suction tube is submerged in the mixture.

[0073] Figure 1 shows the lower position, while the upper position is shown only by a dashed line.

[0074] The finished mixture can be removed through the suction tube 14. In this embodiment, the suction tube 14 is also double-walled, allowing the transport gas to be supplied through the double-wall cavity via the supply unit 15. The mixed material is removed through the suction tube 14 and separated from the transport gas in a separator or filter 16. The transport gas can be completely reintroduced into the container via the inlet 15 and may be designed as a protective gas, such as dry air, to prevent unwanted wetting of the mixture. The mixture separated from the transport gas in the filter 16 may be discharged at the lower end of the filter via a flap or locking system (not shown).

[0075] Figure 2 shows a second embodiment of the apparatus according to the present invention. Wherever possible, the same reference numerals are used for elements similar to those shown in the embodiment of Figure 1.

[0076] Therefore, only the differences from the embodiment in Figure 1 are shown below.

[0077] Here, the mixing tool 3 has a significantly large number of circular mixing sections 10. The lower mixing section 9 has only downward-rolling components 12. There are no upward-rolling components 11. The mixing container has an opening at the container base 2, which can be opened by a ball-segmented closing mechanism 17 to empty the container. The mixed material falls out of the contents discharge port into the collection tray 18 of the transport device. The transport device is pneumatically operated in the illustrated embodiment. The mixture is transported by a transport fluid along a conduit 19 to a separator 16. The transport fluid is then returned to the mixing container via a conduit 20 and back to the collection tray 18 via a conduit 21. The system can be made inherently airtight, and as a result, a protective gas atmosphere can be maintained.

[0078] Here, since the container base 2 has a contents discharge port, the cooling or heating device is designed somewhat differently. The temperature-controlled fluid is supplied via the inlet and outlet 8 of the cooling device through a conduit 22 extending within the double wall of the container base 2 and withdrawn again through a conduit 23 extending just below the height of the temperature-controlled fluid. The temperature-controlled fluid is circulated by a pump, and the heat removed from the double jacket is dissipated to a second cooling circuit located outside via a heat exchanger. The fluid height within the double jacket is automatically kept constant by pumping the temperature-controlled fluid through the circuit.

[0079] Alternatively, the mixing vessel could be equipped with a double jacket only on its side walls, so that the supply pipeline 22 terminates near the bottom of the vessel.

[0080] In a particularly preferred embodiment of the method according to the present invention, the sequence of operations schematically shown in Figure 3 is used.

[0081] In step 1), an additive used in the manufacture of the electrode mixture, such as a conductive additive, is divided into several parts, for example, two parts. The first part is then mixed with the active material in step A). ​​The purpose of this step is to ensure that the active material is surrounded or coated by the additive part.

[0082] Only after this, in step 2), another portion of the additive (the remaining portion in this example) is added, and in step B), the active material and the additive are mixed together. This process allows the active material to be better coated with the additive.

[0083] If the entire amount of additive is added simultaneously, the additive itself may tend to form aggregates and separate from the active material, so considerable care must be taken during the mixing process. When a rotary mixing tool is used, the peripheral speed of the mixing tool in step B) should be 10 m / s to 80 m / s, preferably 20 m / s to 50 m / s, and ideally 25 m / s to 35 m / s. A smaller peripheral speed may be selected in step A).

[0084] Step W verifies whether the desired raw material has already been added completely. If it has been added, the process proceeds to step C. If it has not been added, and the binder has not yet been added in the example described, steps K), A), K), and B) are repeated until all the desired components have been added completely.

[0085] In a preferred embodiment, all binder components are added in this manner by steps K), A), K), and B).

[0086] In the second step A) (after step K), the reactants of the electrode mixture are mixed together. A further step B) follows a further step K), in which a second mechanical power P2 is again introduced into the material contained in the container by shear force.

[0087] In particular, step B), but all other steps as well, can be carried out using a mixing tool having sharp edges and rotating at high speed, or in a well-designed mixer equipped with such a mixing tool. During the steps, heating occurs by applying mechanical power P2, which can be increased by appropriate external thermal energy or reduced by heat dissipation to the outside. The temperature reached in the mixture remains below 70°C according to the present invention. This is because it is remarkably sufficient for the polymer of the plastic binder to adhere reliably to the particle surface and be stretched into a filamentous structure, thereby forming a network structure into which the previously formed particle composite structure is incorporated. At 70°C, the temperature is remarkably lower than the 80°C–120°C temperature range that was considered optimal for the fibrillation of PTFE. However, this temperature has been proven to be perfectly sufficient for the polymer to adhere optimally to the particle surface. Due to strong and intentional fibrillation and the formation of associated network structures, lumpy or even plastic paste-like masses are generated within the mixer, making discharge, transport, and ultimately precise and uniform metering and coating onto the metal foil difficult.

[0088] Finally, in step C), the mechanical power P3 is reduced compared to the mechanical power P2 to avoid destroying and shortening the formed fibrils or polymer fibers, and to facilitate the formation of finer and thinner fibers by adhesion or bonding to the particle surface and stretching. This avoids further temperature increases and crushing of the formed fiber length. Cooling should also be avoided as much as possible to allow the mass to stabilize at a nearly constant temperature level. The fibrillated mass becomes more plasticized, forming a paste-like, easily moldable mass depending on the binder content.

[0089] If a sufficiently malleable plastic mass has already been produced in step B) and it cannot be further improved, or is hardly improved, by stabilization in step C), then step C) can be shortened to a few seconds or omitted entirely.

[0090] Step D) follows, in which the plastic mass can be easily removed from the mixer, easily transported between the mixer and subsequent processing steps, ideally over a distance of several meters, and, most importantly, transformed into a form that can be easily measured and applied. In this step D), the mixture is heated to a temperature of, for example, 45°C T. L As the material cools down, a fourth mechanical power P4 is introduced, which is also smaller than the second mechanical power P2. The fourth mechanical power P4 may also be selected to be smaller than the third mechanical power P3. When mixed tools are used, the peripheral speed may be reduced to, for example, 5 m / s or less.

[0091] During cooling, the plastic mass "solidifies" and, due to the movement of the mixing tool and rotary mixing vessel, breaks down from a lumpy structure into a brittle structure with a very broad particle size distribution. The lower the mixing temperature, the more brittle the mixture becomes. Although the mixture is easily transported at this point, it is still difficult to measure and dispense due to its broad particle size distribution, especially when uniform dispensing is required over a wider dispensing cross-section.

[0092] To further improve the metering and coating characteristics, the mixture is further pulverized in step E) after cooling, which is achieved, for example, by a mixing tool used, which is operated at a significantly increased second mixing speed, thereby introducing a fifth mechanical power P5. When a mixing tool is used, the peripheral speed of the mixing tool can be increased, for example, to 5 m / s to 20 m / s.

[0093] This generates aggregates with an average particle size of 0.05 mm to 5 mm, and therefore allows for extremely good weight-based metering and coating over a wide metering and coating cross-section. This produces the corresponding electrode mixture. This mixture is rolled in step F) and laminated onto a discharge foil to produce an electrode. [Examples]

[0094] A preferred embodiment is shown below.

[0095] [Table 1]

[0096] In Embodiment 4, no additives are used. In Embodiments 1 and 2, the binder is already added in step A). ​​In all other embodiments, the binder is added either first in step B) or in the last step B) or first step K) performed. Steps C) to E) are omitted in the second and third embodiments. Step D) is performed in the first embodiment and Embodiments 4 to 7, while steps C) and E) are optional.

[0097] At least the final step B) is indicated to be carried out for 3 to 30 minutes, preferably 3 to 10 minutes. The temperature at the end of step B) should be less than 70°C, preferably between 50°C and 70°C.

[0098] Step C) is preferably carried out for 1 to 10 minutes, during which time the temperature of the incorporated material is kept nearly constant. If necessary, step C) may be carried out for a longer period to achieve significant improvements in the network structure.

[0099] During step D), the product is cooled and simultaneously coarsely ground. This step should be carried out for 3 to 90 minutes, particularly preferably 3 to 30 minutes, and the temperature should drop to below 45°C, preferably below 40°C, and preferably below 35°C.

[0100] Step E) should be carried out for only a short time, preferably 5 to 30 seconds, between 5 and 60 seconds. The temperature should not rise again, or at least change only slightly. [Explanation of symbols]

[0101] 1. Container wall 2 Bottom of container 3 Mixing tools 4 motors 5. Drive belt 6. Inner compartment of double wall 7. Outer compartment of double wall 8. Fluid supply and discharge section 9, 10 Mixing section 11, 12 Rolling parts 13 Wall scraper 14 Suction tube 15 Inlet 16 Separator 17. Ball segment closing mechanism 18 Collection Tray 19, 20, 21, 22, 23 pipes

Claims

1. from various substances, namely, an active material with a mass fraction w １ , optionally an additive with a mass fraction w ２ , and a binder with a mass fraction w ３ , a method for producing an electrode mixture, wherein w １ and w ３ are each greater than 0%, w ２ is 0% or more, w １ , w ２ , and w ３ are each less than 100%, as follows 1) The first percentage p of the active material and the additive. ａ１ , and / or the first percentage p of the binder ｂ１ The process of filling a container with [Math 1] and [Math 2] However, [Math 3] or [Math 4] The process is one of the following: A) A first mechanical power P is applied to the substance contained in the container by shear force or impact force. １ A process for introducing a process in which shear force is preferred, 2) The second percentage ratio p of the additive ａ２ and / or a further percentage p of the binder ｂ２ A step of filling the container with the above, [Math 5] and [Math 6] The process, B) In order to produce the second mixture, the second time interval T ２ During this time, a second mechanical power P is applied to the substance contained in the container by shear force or impact force. ２ A process to introduce a shear force, P ２ >P １ The process, Includes, W) A process in which steps A) and B) are repeated unless the binder and any additives are completely introduced, and step K) is performed between steps A) and B), K) Further percentage p of the additive ａｋ and / or a further percentage p of the binder ｂｋ The process involves filling the container with the following: in the first iteration, k = 3, and after each iteration, k is increased by 1. 【Number 7】 and [Number 8] That is, method.

2. lol ２ >0%, p ａ１ >0%, and p ｂ１ The method according to claim 1, characterized in that = 0%.

3. At least during the last execution of step B), preferably during all executions of step B), the temperature of the substance contained in the container reaches a predetermined temperature T. Ｈ Take care to ensure that it does not exceed T Ｈ >40°C, particularly preferably 40°C<T Ｈ <80℃, 50℃ in the best case <T Ｈ The method according to claim 1 or 2, characterized in that the temperature is 70°C.

4. At least during the last execution of step B), preferably during the entire execution of step B), the power P is used to raise the temperature of the substance taken into the container during step B). ２ The temperature of the substance taken into the container is set to the predetermined temperature T. Ｈ The method according to any one of claims 1 to 3, characterized in that step B) is terminated immediately upon reaching a certain point.

5. After the final execution of process B), Process C) Third time interval T ３ During this time, a third mechanical power P is applied to the substance contained in the container by shear force or impact force. ３ A process to introduce a shear force, P ３ <P ２ The process, The method according to any one of claims 1 to 4, characterized in that the following occurs.

6. T ３ <T ２ The method according to claim 5, characterized in that...

7. In step C), the temperature of the substance contained in the container is 0.8 × T Ｈ and 1.1 × T Ｈ Between, preferably 0.9 × T Ｈ and 1.05 × T Ｈ The method according to claim 5 or 6, characterized in that the power is set to be maintained between and .

8. After the final execution of step B), and if applicable, after step C), D) The substance contained in the container is heated to temperature T Ｌ <T Ｈ As it cools down, the fourth mechanical power P is generated by shear force or impact force. ４ A step of introducing into the substance in the container, wherein a shear force is preferred, P ４ <P ２ The process, The method according to any one of claims 1 to 7, characterized in that the following occurs.

9. After step D), E) P ５ >P ４ The fifth mechanical power P ５ A step of crushing the substance contained in the container by introducing a compound, wherein the aggregate preferably has an average particle size of 0.05 mm to 5 mm. The method according to claim 8, characterized in that the following continues.

10. The method according to any one of claims 1 to 9, characterized in that, at least during the last step of step B), step B) and preferably all steps of the process are carried out in a protective gas atmosphere.

11. The method according to any one of claims 1 to 10, characterized in that a polymer binder, preferably PTFE or PVDF, is used as the binder, with PTFE being particularly preferred.

12. A method for manufacturing an electrode, comprising manufacturing an electrode mixture by the method described in any one of claims 1 to 11, rolling the electrode mixture and laminating it onto a discharge foil, or pressing it onto a discharge foil.

13. It is a device, An apparatus for carrying out the method according to any one of claims 1 to 11, wherein the apparatus comprises a mixing container having a mixing container wall and a mixing container bottom, a mixing tool disposed inside the mixing container, and a wall scraper, wherein the mixing tool is rotatable about a tool axis w, the mixing container is rotatable about a container axis b, and the tool axis w and the container axis b are spaced apart from each other.

14. The apparatus according to claim 13, wherein a heating and / or cooling device is provided for cooling the mixed materials disposed in the mixing container, the mixing container is preferably designed to have a double wall so that a cooling or heating fluid can pass between the two walls of the double wall, and particularly preferably at least a portion of the base of the mixing container is also designed to have a double wall so that a cooling or heating fluid can pass between the two walls of the double wall.

15. The apparatus according to claim 13 or 14, characterized in that, during operation of the apparatus, the mixing tool and the mixing container are rotated in the same direction about the tool axis w or the container axis b.

16. The apparatus according to any one of claims 13 to 15, characterized in that the wall scraper is in contact with the wall of the mixing container and / or the mixing tool is in contact with the base of the mixing container, wherein the wall scraper and / or the mixing tool are made of plastic, more preferably PTFE or polyamide, in at least the portion that is in contact with the wall of the mixing container or the base of the mixing container.

17. The apparatus according to any one of claims 13 to 16, wherein the mixing tool comprises a tool shaft and at least one mixing portion projecting radially beyond the tool shaft, the mixing tool preferably comprises a plurality of mixing portions spaced apart from each other in the axial direction, and / or the mixing portion comprises a shearing component disposed within a virtual annulus and a rolling component projecting radially beyond the shearing component.

18. The apparatus according to any one of claims 13 to 16, characterized in that a pneumatic conveying device is provided so that the mixed material can be transported outside the mixing container.

19. The apparatus according to claim 18, characterized in that the pneumatic conveying device is located in or can be located in the mixing container as a suction tube, and the suction tube is preferably incorporated into the wall scraper.

20. The apparatus according to claim 18, characterized in that the base of the mixing container has a closable outlet, and an air transport pipeline is located below the outlet so that the mixed material coming out of the mixing container through the outlet falls into the air transport pipeline.

21. The apparatus according to claim 19 or 20, characterized in that the pneumatic conveying device is operated with an inert gas, and the inert gas is preferably conveyed in a closed circuit.

22. Use of the apparatus according to any one of claims 13 to 21 for carrying out the method according to any one of claims 1 to 11.

23. An electrode mixture prepared by the method described in any one of claims 1 to 11.

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