Discrete Element Method Model of An Extrusion Process with Recirculation for Dry Manufacturing of Lithium-Ion Battery Electrodes

In this article, we report a computational modeling study to enhance the understanding of the solvent-free extrusion process employed to produce filaments for the 3D printing of lithium-ion battery electrodes. Our study is supported by a newly developed dynamic 3D-resolved numerical model capable of simulating the extrusion process, including material recirculation within the extruder. This model describes the extrusion process at the mesoscale through a granular approach based on the discrete element method. Our model accounts for the main features of the twin-screw extruder, allowing the simulation of several recirculation cycles and extrusion of active material, carbon additive, and binder mixtures. We discuss how different electrode material formulations, material injection sequences, twin-screw rotation speeds, and residence time in the extruder barrel affect the microstructure and particle distribution of the extruded filament. Finally, we calculate parameters including the porosity, tortuosity factor, effective diffusivity and electrical conductivity of the filament microstructures.