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DE-102024132785-A1 - Mixer for producing an electrode mixture with pressure-based conveying device

DE102024132785A1DE 102024132785 A1DE102024132785 A1DE 102024132785A1DE-102024132785-A1

Abstract

The present invention relates to a mixer for producing an electrode mixture, comprising a mixing vessel rotatable about a mixing vessel axis and having a rotationally symmetrical and preferably circular vessel bottom and vessel wall, a scraper device movable relative to the mixing vessel and touching the vessel bottom or having a distance of less than 2 mm from the vessel bottom, and a pressure-based conveying device for removing the electrode mixture from the mixing vessel, wherein the pressure-based conveying device has a conveying channel arranged on or in the scraper device with an inlet located near the vessel bottom and an outlet.

Inventors

  • Clemens Schmitt

Assignees

  • MASCHINENFABRIK GUSTAV EIRICH GMBH & CO KG

Dates

Publication Date
20260513
Application Date
20241111

Claims (15)

  1. Mixer for producing an electrode mixture comprising a mixing vessel rotatable about a mixing vessel axis and having a rotationally symmetrical and preferably circular vessel bottom and vessel wall, a scraper device movable relative to the mixing vessel and touching the vessel bottom or having a distance of less than 2 mm from the vessel bottom, and a pressure-based conveying device for removing the electrode mixture from the mixing vessel, wherein the pressure-based conveying device has a conveying channel arranged on or in the scraper device with an inlet located near the vessel bottom and an outlet.
  2. Mixer according to one of the preceding claims, characterized in that a mixing tool is provided in the mixing container, which is rotatable about a mixing tool axis, wherein the mixing container axis and the mixing tool axis are spaced apart from each other by a distance a ≥ 0 and are arranged parallel to each other.
  3. Mixer according to one of the preceding claims, characterized in that the scraper device has a first end which touches the container wall or is less than 2 mm away from the container wall, and a second end which is further away from the container wall than the first end, wherein the inlet of the conveying channel is arranged closer to the second end than to the first end, wherein preferably the distance of the inlet from the first end is at least twice and particularly preferably at least four times as large as the distance of the inlet from the second end.
  4. Mixer according to one of the preceding claims, characterized in that the scraping device has a wall section extending from the bottom of the container along the container wall, which touches the container wall or has a distance from the container wall of less than 2 mm.
  5. Mixer according to one of the preceding claims, characterized in that the scraper device has an upstream side to which the electrode mixture flows during operation due to the direction of rotation of the mixing vessel, wherein the inlet is arranged on the upstream side and preferably also on the side facing the bottom of the vessel.
  6. Mixer according to one of the preceding claims, characterized in that the scraper device has a guide lip on its side facing the bottom of the container, which is preferably made of a plastic, wherein the guide lip is arranged and designed in such a way that, during operation of the mixer, it directs the electrode mixture on the bottom of the container towards the inlet.
  7. Mixer after Claim 6 , characterized in that the guide lip surrounds the inlet on the side facing the bottom of the container, at least on the side facing away from the upstream side.
  8. Mixer according to one of the preceding claims, characterized in that the conveying channel has a circular cross-section.
  9. Mixer according to one of the preceding claims, characterized in that the scraper device is convexly curved or saddle-roof-shaped or pent-roof-shaped on its side facing away from the bottom of the container.
  10. Mixer according to one of the preceding claims, characterized in that the outlet is connected to a vacuum source.
  11. Mixer after Claim 2 or a dependent claim thereof, characterized in that the distance between the container axis and the axis of the mixing tool is a>0 and the mixing tool has at least one swirling element which is in contact with the container bottom or has a distance to the container bottom which is less than 2 mm, wherein the swirling element never penetrates an outer circular ring of the container bottom during the rotation of the mixing container and the rotation of the mixing tool and the second end extends at least to the inner edge of the circular ring, wherein preferably the inlet extends at least to the inner edge of the circular ring.
  12. Mixer according to one of the preceding claims, characterized in that an imaginary line passing through both the first and second ends forms an angle α with a tangent to the circular base of the container at the point where the imaginary line intersects the circular circumference of the base of the container, which is less than 90°, preferably between 30° and 60° and best between 40° and 50°.
  13. Mixer according to one of the preceding claims, characterized in that a supply air duct with a supply air outlet is provided.
  14. Mixer after Claim 13 , characterized in that the supply air outlet is arranged such that the supply air flowing out through the supply air outlet is directed either towards the inlet of the conveying channel or towards an area arranged upstream of the inlet of the conveying channel.
  15. Use of a mixer according to one of the preceding claims for the production of a dry electrode mixture.

Description

The present invention relates to a mixer for producing an electrode mixture, comprising a mixing vessel rotatable about a mixing vessel axis and having a rotationally symmetrical and preferably circular vessel bottom and wall. Such mixers are generally known. However, their use for producing electrode mixtures is limited. This is partly due to the fact that the mixture, and especially dry electrode mixtures, often needs to be heated and cooled as quickly as possible during production. This is only easily achievable if the container wall and the entire bottom of the mixing container have a double jacket to accommodate a cooling and/or heating fluid, thus eliminating the need for a drain plug in the bottom. Removing the finished mixture from the mixing container then becomes difficult, as the mixture often has a sticky, clay-like consistency. Electrode mixtures are used, for example, in the production of batteries. In recent years, battery technology, and lithium-ion technology in particular, has moved into the spotlight, as it is essential for the functionality of, for example, fully electric vehicles, but also for stationary energy storage systems. A typical lithium-ion cell has a copper foil acting as the anode and an aluminum foil acting as the cathode. The foils are usually coated on both sides with active material and, at least for the production of a cathode, with additives. Furthermore, the particles of the active material must be bonded both to each other and to the metal foil, for which a binder material is used. To produce the layers, the starting materials, i.e., the active material, the binder, and, if applicable, the additives, must be mixed together and dispersed into a slurry. A liquid solvent, such as water, is usually added for this purpose, which then has to be removed again in complex drying processes after the electrode mixture has been applied to the foil. Since this is very time-consuming and energy-intensive, there is a need for the production of dry electrode mixtures of sufficient quality for manufacturing dry electrodes. Due to the complex properties of the active material used—often PTFE—the electrode mixture must be heated during the mixing process, usually to more than 45 °C. To process PTFE, shear forces often need to be applied to fibrillate it, i.e., to break it down into a multitude of fine fibers or fibrils. However, when heated, it is not easy to remove the electrode mixture from the mixing container because it has a highly adhesive, clay-like consistency. Cooling the mixture might improve its removal, but this is also time-consuming, especially since the mixing container must be reheated immediately after removing the electrode mixture to process the next batch. The object of the present invention is therefore to provide a mixer for producing an electrode mixture which enables early removal of the electrode mixture even under difficult conditions. According to the invention, this problem is solved by providing a scraper device which is movable relative to the mixing container and touches the bottom of the container or is less than 2 mm away from the bottom of the container, as well as a pressure-based conveying device for removing the electrode mixture from the mixing container. A pressure-based conveying device is a device for transporting fluid or solid materials through a conveying channel, such as a pipe or hose, by generating a controlled pressure differential between an inlet and an outlet. This pressure differential causes a continuous material transport, in which, depending on the device's design, a gas, a liquid, or the material being conveyed itself is used as the conveying medium. The pressure differential can be achieved either by generating an overpressure (pressure conveying) or a vacuum (vacuum conveying). Pressure-based conveying systems include, in particular: • Pneumatic conveying systems that use gases – typically air – as the conveying medium and are particularly suitable for transporting solid particles such as powders or granules. The material is drawn in by the flow of the conveying gas or transported by pressure within the conveying element. • Hydraulic conveying systems that use liquids as the conveying medium and are frequently used for transporting liquids or liquid mixtures such as emulsions or suspensions Pensions are used. The flow of the liquid moves the material in the conveying element. These conveying systems enable the transport of various material forms, such as liquids, suspensions, powders, or granular solids. They are designed so that the flow generated by the pressure difference transports the material safely and efficiently. The present invention has been developed for the production of dry electrode mixtures. This is also the preferred use of the mixer according to the invention. However, it can also be used for wet electrode mixtures. The invention is explained below with reference to the production of dry electrode mixtures. It i