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DE-102024132793-A1 - Methods for the production and conditioning of electrode mixtures and of dry electrodes from the electrode mixtures

DE102024132793A1DE 102024132793 A1DE102024132793 A1DE 102024132793A1DE-102024132793-A1

Abstract

The present invention relates to a method for producing and conditioning an electrode mixture consisting of active material, optionally additives and binder, comprising the steps 1) Producing the electrode mixture in a mixing vessel of a mixer, wherein during the production the mixture is heated to a temperature T<sub> H </sub> where T<sub> H </sub>> 45°C, 2) Removal of the electrode mixture from the mixing container, 3) Applying the electrode mixture to a sieve which separates the electrode mixture into a sieve pass and a sieve overflow, and 4) Using the sieve pass as a conditioned electrode mixture.

Inventors

  • Stefan Gerl

Assignees

  • MASCHINENFABRIK GUSTAV EIRICH GMBH & CO KG

Dates

Publication Date
20260513
Application Date
20241111

Claims (10)

  1. Method for producing and conditioning an electrode mixture consisting of active material, optionally additives and binder, comprising the steps of: 1) producing the electrode mixture in a mixing vessel of a mixer, wherein during production the mixture is heated to a temperature T<sub> H</sub> , where T <sub>H </sub>> 45°C, 2) removing the electrode mixture from the mixing vessel, 3) applying the electrode mixture to a sieve which separates the electrode mixture into a sieve pass and a sieve overflow, and 4) using the sieve pass as a conditioned electrode mixture.
  2. Procedure according to Claim 1 characterized in that the sieve has a mesh size of less than 10 mm and especially preferably of less than 5 mm and best of less than 2 mm.
  3. Procedure according to Claim 1 or 2 , characterized in that a friction sieve or a vortex sieve is used as the sieve.
  4. Method according to one of the preceding claims, characterized in that the sieve is used in such a way that no sieve overflow remains.
  5. Method according to one of the preceding claims, characterized in that after step 1) 1a) cooling of the electrode mixture in the container 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, and after step 2) the following steps 2a) supplying the electrode mixture to a cooling device, 2b) cooling of the electrode mixture after step 2a) by at least 4°C, preferably to a temperature T K < 19°C by means of the cooling device.
  6. Procedure according to Claim 5 , 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 2a) and 2b), wherein preferably in step 1a), between step 1a) and step 2b) and/or during step 2b) dry ice or liquid gas is introduced into the mixing container, and the gas produced by sublimation or evaporation is directed into the conveying line.
  7. Procedure according to one of the Claims 1 until 4 , characterized in that after step 2) and before step 3) the following occurs: 2a1) transferring the electrode mixture into a cooling mixer with a cooling vessel, the walls of which are preferably cooled, 2a2) cooling the electrode mixture in the cooling vessel by at least ΔT = 5°C to a withdrawal temperature T E , which is preferably < 35° C, 2a3) withdrawal of the electrode mixture from the cooling vessel.
  8. Procedure according to Claim 5 , 6 or 7 , characterized in that the electrode mixture is transferred to a buffer tank after step 2) or, if present, after step 2a3) and before steps 3) and 4), wherein the buffer tank is preferably temperature-controlled and is used as a cooling device in steps 2a) and 2b), wherein the buffer tank is preferably double-walled, with a cooling fluid being able to flow between the two walls, and/or the buffer tank has thermal insulation, wherein the electrode mixture is particularly preferably moved in the buffer tank.
  9. A method for producing dry electrodes from electrode mixtures produced by a method according to one of the preceding claims, characterized in that the electrode mixture is 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, and the cut-off edge strips or excess material are fed into the container, the cooling container, the buffer container or into the conveying line.
  10. Procedure according to Claim 9 , characterized in that a comminution device is provided which divides the separated edge strips into smaller strip sections or a fine bulk material.

Description

The present invention relates to a method for producing and conditioning dry electrode mixtures. Furthermore, the present invention relates to a method for producing dry electrodes from these electrode mixtures. 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 significant role in the future. Besides more cost-effective, but lower-performing, cobalt-free sodium-ion cell chemistries, intensive research is also being conducted on all-solid-state batteries with solid electrolytes. This technology theoretically offers an even higher energy density than conventional lithium-ion batteries and, due to the solid electrolyte, even greater safety. The production of all these batteries will likely continue to require 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 materials science and the requirements of electromobility. A typical lithium-ion cell electrode consists of 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 cathode, with additives. The electrodes must meet high standards in order to produce a reliable, high-capacity lithium-ion battery. The electrode layer must have a defined, constant thickness and a defined pore structure into which the electrolyte can penetrate to transport lithium ions to each particle of the active material. Ideally, the active material should be wetted by the electrolyte over as large an area as possible. Furthermore, the particles of the active material must be electrically connected to the metal foil, i.e., in the described example, to the copper or aluminum foil, to ensure the transport of electrons to and from each particle of the active material. Furthermore, the particles of the active material must be bound 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 across the width and length. To produce the layers for dry electrodes, the starting materials, i.e. the active material, the binder and, if applicable, the additives, must be mixed together and prepared to form a so-called structured mixture. Electrode mixtures for dry electrodes are produced with either little or, more commonly, no solvent at all. However, more intensive preparation of the components is necessary during mixing to ensure the polymeric binders used are no longer soluble in a solvent as is usually the case. to convert the mixture into a processable and bondable state. Especially when PTFE or PVDF is used as a binder, the mixture usually needs to be processed in successive steps at different temperatures. When using PTFE, the mixture is fibrillated by temperature activation and the input of shear energy at temperatures above 30°C. The nano- and microscale polymer fibers formed during fibrillation create a crumbly to plastic mass that is very difficult to remove from the mixer. Since the mixture then needs to be evenly metered into a calender gap to produce the desired electrode film, the crumbly to plastic mass is often unusable. The mass must first b