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DE-102024132779-A1 - Method for producing dry electrodes from electrode mixtures

DE102024132779A1DE 102024132779 A1DE102024132779 A1DE 102024132779A1DE-102024132779-A1

Abstract

The present invention relates to a method for producing dry electrodes from electrode mixtures produced in a mixing and/or conditioning process, in which the electrode mixtures are fed to a calender and calendered into a web, wherein the edge strips of the web or excess material are then cut off to ensure a uniform width of the web, characterized in that the cut-off edge strips or the excess material are fed to a comminution device which divides the cut-off edge strips into smaller strip sections which are fed to the mixing and/or conditioning process to produce a further electrode mixture.

Inventors

  • Stefan Gerl

Assignees

  • MASCHINENFABRIK GUSTAV EIRICH GMBH & CO KG

Dates

Publication Date
20260513
Application Date
20241111

Claims (10)

  1. A method for producing dry electrodes from electrode mixtures produced in a mixing and/or conditioning process, in which the electrode mixtures are fed to a calender and calendered into a web, wherein the edge strips of the web or excess material are then separated to ensure a uniform width of the web, characterized in that the separated edge strips or excess material are fed to a comminution device which divides the separated edge strips into smaller strip sections which are fed to the mixing and/or conditioning process to produce a further electrode mixture.
  2. Procedure according to Claim 1 , characterized in that a Venturi nozzle, a discontinuous crushing mixer, a continuous crushing mixer, a granulator, a mill or a knife rotor is used as the crushing device.
  3. Procedure according to Claim 1 or 2 , characterized in that a process is used for the production and conditioning of the electrode mixtures, which consist of active material, optionally additives and binder, comprising step 1) producing the electrode mixture in a mixing vessel, wherein during production the mixture is heated to a temperature T H , where T H > 45°C.
  4. Procedure according to Claim 3 , characterized in that the manufacturing and conditioning process according to step 1) comprises the following steps: 2) Cooling the electrode mixture in the mixing vessel by at least ΔT = 5°C and preferably to a temperature T MAX < 35°C, but not below a withdrawal temperature T E > 24°C, 3) Withdrawing the electrode mixture at the withdrawal temperature and feeding the electrode mixture to a cooling device, 4) Cooling the electrode mixture according to step 2) by at least 4°C, preferably to a temperature T K < 19°C by means of the cooling device.
  5. Procedure according to Claim 4 , characterized in that a conveying line of a pneumatic conveying system for removing the electrode mixture from the mixing container, which is operated with a gas, preferably with a temperature T G < 19°C, is provided as a cooling device in steps 3) and 4), wherein preferably in step 2), between steps 2) and 3) and/or during step 3) dry ice or liquefied gas is introduced into the mixing container, and the gas produced by sublimation or evaporation is directed into the conveying line.
  6. Procedure according to Claim 4 or 5 , characterized in that the electrode mixture according to step 2) is transferred into a buffer container, wherein preferably the buffer container is temperature-controlled and is used as a cooling device in steps 3) and 4), wherein the buffer container is preferably double-walled, wherein a cooling fluid can flow between the two walls, and/or the buffer container has thermal insulation, wherein the electrode mixture is particularly preferably moved in the buffer container.
  7. Procedure according to one of the Claims 3 until 6 , characterized in that the electrode mixture according to step 1) and preferably according to step 3) is applied to a sieve and only sieve passage is used as conditioned electrode mixture, wherein preferably the sieve has a mesh size of less than 10 mm and particularly preferably of less than 5 mm and best of less than 2 mm.
  8. Procedure according to Claim 7 characterized in that the sieve overflow is directed into the mixing container, the cooling mixer, the buffer container, a crushing device or into the conveying line.
  9. Procedure according to Claim 7 , characterized in that a friction sieve or, more preferably, an eddy current sieve is used as the sieve, wherein the use is preferably carried out in such a way that no sieve overflow remains.
  10. Method according to one of the preceding claims, characterized in that the separated edge strips or the excess material are fed into the mixing container, the cooling mixer, the buffer container or into the conveying line.

Description

The present invention relates to a method for producing dry electrodes from electrode mixtures produced in a mixing and/or conditioning process, in which the electrode mixtures are fed to a calender and calendered into a web, wherein the edge strips of the web or excess material are then cut off to ensure a uniform width of the web. A calender for manufacturing electrodes from a dry electrode mixture typically consists of several coordinated components that enable precise compaction and shaping of the electrode mixture. The basic structure of such a calender usually includes the following main components: 1. Roller pair: The core of the calender consists of two parallel rollers rotating in opposite directions at the same or different speeds. The rollers are made of high-strength material and can often be heated to improve the processing properties of the electrode compound. The roller surfaces can be smooth or textured to achieve the desired electrode surface structure. 2. Roll gap: The distance between the two rolls, the so-called calender or roll gap, is precisely adjustable and determines the thickness of the resulting electrode. Accurate control of this gap is crucial to ensure the required homogeneity and thickness of the electrodes. 3. Feed unit: The electrode mixture is continuously introduced into the roller gap via a feed unit. This unit may include conveying systems such as belts or hoppers to ensure a uniform and controlled material feed. 4. Receiving unit: After calendering, the finished electrode is transported further via a receiving unit. This can be, for example, a conveyor belt or another rotating roller that transfers the electrode to the next process step. 5. Edge cutter: To trim the edges of the electrode film to an exact width, the calender can be equipped with an edge cutter that removes material laterally, thus adjusting the electrode geometry. 6. Laminating unit: The formed electrode film must then be laminated onto the conductive foil. For this purpose, the electrode film and the conductive foil are guided between a rotating pair of rollers, and the electrode film is pressed onto the conductive foil. In some processes for manufacturing dry electrodes, the film formation and lamination onto the conductive foil takes place directly in the first roller gap below the feeding unit. By precisely controlling pressure, temperature and gap width, the calender produces a homogeneous electrode film with a defined thickness and smooth surface, suitable for further processing into battery cells. In recent years, battery technology, and in particular lithium-ion technology, 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 long-lasting, high-capacity battery that is cost-effective to manufacture is a prerequisite for the acceptance of fully electric vehicles. Currently, lithium-ion batteries are predominantly used. Within this category, several specific cell chemistries dominate, with the following being the most widespread cathode materials: • Nickel-manganese-cobalt (NMC) electrode mixture: These cells use a mixture of nickel, manganese, and cobalt. The nickel ensures high energy density, manganese provides thermal stability, and cobalt stabilizes the structure. • Nickel-cobalt-aluminum (NCA) electrode mixture: This mixture contains nickel, cobalt, and aluminum in the cathode. The aluminum content stabilizes the structure and improves the lifespan, while nickel maximizes the energy density. • Lithium iron phosphate (LFP) electrode mixture: In this cobalt-free cell chemistry, lithium iron phosphate is used as the cathode material, which is less energy-dense but offers a longer lifespan and better thermal stability. The anodes usually consist of graphite or silicon-graphite mixtures. For all these types, electrode mixtures are produced using polymeric binders, sometimes also with conductive additives, applied to conductive foils, and calendered during or after this process to optimize the structural integrity and density of the electrodes. Furthermore, there are developments that could play a relevant role in the future. Besides more cost-effective but lower-performing, yet cobalt-free sodium-ion cell chemistries, intensive research is also being conducted on all-solid-state batteries with solid electrolytes. This technology theoretically offers even higher energy density than conventional lithium-ion batteries and, due to the solid electrolyte, even greater safety. The production of all these batteries is expected to continue requiring calendered electrodes, which present various calendering challenges. In summary, the calendering of electrode mixtures will continue to play an important role in future battery technologies, as it optimizes the density, homogeneity, and mechanical properties of the electrodes. However, the specific materials that will be used will depend on advances in