Continuous Processing of Cathode Slurry by Extrusion for Lithium‐Ion Batteries

Abstract

In this work, detailed investigations concerning a continuous mixing process for lithium‐ion battery (LIB) electrodes are conducted. NCM622 (Li(Ni0.6Co0.2Mn0.2)O2) cathode electrodes are fabricated on behalf of a corotating twin screw extruder. Studies are performed concerning different material compositions and processing parameters, such as screw speed. Processing routes in relation to feeding of binder to the process zones as a dry powder or presolved in a liquid are examined. The produced cathode slurries are analyzed concerning rheological properties and dispersing degree, meaning particle size distribution. Subsequently, the coated electrodes are characterized regarding electrical conductivity, mechanical properties, and pore size distribution. Up to the present, the continuous mixing process of LIB electrodes is barely investigated. This study provides deep insight into the process–structure–property relations of the continuous mixing process.

Scalable Production of Separator and Cathode Suspensions via Extrusion for Sulfidic Solid‐State Batteries

“…In addition to a high shear rate and thus, improved dispersing effect, the continuously operating system, which is available with throughputs of several tons per hour, raises the scaling of suspension production to a new level. [14,23,24] Analogous to the other PRs, the separator suspension was processed (PR A S , PR B S ). With only the SE in powder form, a dry mixing step is not required.…”

“…[14] Alternatives from the field of conventional lithium-ion batteries that meet these requirements are planetary mixers, kneaders and twinscrew extruders. [22][23][24] Based on this and taking into account the identified challenges, this publication aims to establish and improve an industrially scalable dispersion process under inert gas atmosphere.…”

Current Status of Formulations and Scalable Processes for Producing Sulfidic Solid‐State Batteries

“…Otherwise, different speeds and dispersion times are applied depending on the dispersing machine (1,600-2,000 rpm and 3-6 min at the PCM, 2,870 rpm and 60 min at the dissolver). Although systematic process parameter variation for rotational speed and residence time on dissolvers and extruders has only been performed in the production of conventional LIBs, [126,127] a difference in shear intensity can be stated based on indications from the work of Teo et al for PCM based production [128] and by Batzer et al for dissolver based preparation. [59] In both research works PIB is used as a binder but divergent results with respect to the adhesion strength of the coatings were achieved.…”

“…[59] Twin-screw extruders are established and investigated in the field of LIBs. [127] With a mass flow rate of up to 100 t/h [141] these machines are highly relevant for industrial use and probably the future approach for an effective dispersion of sulfide-based electrode and separator slurries. In particular, the ductile character of sulfide-based electrolytes promises a good processability during the extrusion process and the possibility to significantly reduce the solvent amount [127] and result in highly homogeneous electrode and separator layers.…”

“…The effects of sulfide solid electrolytes with different particle sizes were shown on both the dispersion process and the resulting coatings: Whereas more solvent is required for fine solid electrolytes due to the higher specific surface area, advantages result from a more homogeneous dispersion and thus better ionic connection of the active material particles, especially in the production of cathodes [59] . Twin‐screw extruders are established and investigated in the field of LIBs [127] . With a mass flow rate of up to 100 t/h [141] these machines are highly relevant for industrial use and probably the future approach for an effective dispersion of sulfide‐based electrode and separator slurries.…”