The rise of the production of Lithium-ion batteries (LIBs) calls for a global improvement of the electrode manufacturing process. At present, slurry casting is the standard technique. The solvent-free (SF) approach appears as a prominent alternative as it avoids the use of toxic solvents and decreases the environmental impact. Four different processes have been employed in the SF approach: hot pressing, spray deposition, dry process by melting extrusion (MeltE) and 3D printing by material extrusion (3DP). The MeltE approach in the SF porous electrode manufacturing has been proposed recently by a few research groups. [4] Although the stages themselves may vary, the main steps of this process typically adhere to a similar pathway (Fig ). Initially all the raw materials are in solid phase and include active material (AM), carbon additive (CA), permanent binder and sacrificial binder. The latter allows to create the porosity in the electrode and also improves the extrusion processability by increasing the polymer content. Extrusion allows the melting of the binders and facilitates the mixing of all formulation components under high shear rates. This process can be performed in twin-screw extruders (TSE) or in internal mixers. The latter are typically employed only at an academic scale to minimize the use of raw materials. After going through the extruder outlet, the resulting paste solidifies, which allows for subsequent calendering and partial debinding steps. This is necessary for attaining the desired final electrode microstructure. Material extrusion is one of the seven categories of 3D printing. Fused Filament Fabrication (FFF/FDM), a material extrusion process, has been used for SF manufacturing of electrodes. However, some solvent is still required for the mixing stage. A completely solvent-free 3DP is challenging, and to the best of our knowledge only the recent work conducted by our team has achieved this as a proof of concept thus far. The main steps of this process are depicted in Fig 1b . Here AM, CA and two polymers feed the TSE. The key difference is that both polymers are fundamental components of the final electrode microstructure, therefore there is no debinding step. Polypropylene (PP) acts as a binder giving mechanical stability to the electrode, while polycaprolactone (PCL) provides the electrolyte path after soaking with liquid electrolyte. The resulting filament is fed into the 3D printer allowing for the creation of arbitrary shapes of electrodes. All of the above highlights the key importance of the extrusion step in SF electrode manufacturing. As a relatively new application in the battery field, the extrusion process still holds considerable untapped potential for improvement and optimization. To this end, numerical modeling emerges as an exceptionally promising tool. It offers the opportunity to gain a deeper understanding of the extrusion process and explore various avenues for enhancing its efficiency. Numerical modeling of single polymer extrusion has extensively been applied in other fields; recent reviews can be found in and . Basically, the process can be divided in three stages: solid transport, melting and liquid flow. The Discrete Element Method (DEM) is commonly employed for studying the particle-particle and particle-extruder interactions during the first stage. For the second and third stages, continuous approaches, like Computational Fluid Dynamics (CFD) or Smoothed Particle Hydrodynamics (SPH), are more suitable. Recently, Celik et al. proposed an approach coupling DEM and CFD, that allows the study of the three extrusion stages. This approach which presents a high computational cost has not yet been applied to real extruder geometries. The challenge is even greater when modeling the extrusion of dense suspensions, such as those encountered in SF battery electrode manufacturing. This is because in this process, the AM and CA do not melt but are present in high concentrations within the paste. A similar fluidsolid interaction in twin-screw domains arises in other applications such as wet granulation and wet mixing. Washino et al. proposed a CFD-DEM model of wet granulation in a small domain of a mixer. Computational cost can be reduced by implicitly considering the fluid effect on the particles by using a hydrodynamic force. This approach was employed for the simulation of a section of a twin-screw granulator and for the modeling of a dense suspension extrusion in a square-entry die. This methodology ensures a robust representation of the fluid influence; however, this fluid phase is not part of the obtained microstructure. On the other hand, in the slurry casting process, Coarse Grained Molecular Dynamics and DEM methods developed by our research group were able to represent explicitly a liquid phase during slurry, drying and to calibrate their parameters with experimental viscosities and densities. The same methods were applied by our group for the simulation of the calendering process. These are mesostructural approaches, yet, the term microstructural is employed hereafter, as commonly used in the battery field. By considering explicitly the AM solid particles and the other particles, DEM allows to study mixing and aggregation among all the materials. The influence of the dispersion of carbon black was analyzed experimentally and numerically for a small amount of particles. Srivastava et al. related the cohesion and adhesion at the mesostructure with the electrochemical and mechanical properties of the electrode. Finally, Ludwig et al. investigated the scenarios of dry mixing (carbon, binder and active material) for different values of cohesion among the particles in a simple geometry. Finally, for the slurry process, a model was proposed to investigate the behavior of a viscous fluid (high solid content) in a section of a TSE using SPH. This model, using real slurry rheological data, allows to calculate local shear rates, however a microstructure cannot be obtained due to its continuum nature. To the best of our knowledge, the modeling of the extrusion process for the dry manufacturing of electrodes has never been reported before. The present study proposes a new microstructural DEM model of extrusion during SF battery electrode manufacturing. The solid and molten phases are explicitly considered in the entire geometry of a twin-screw extruder. The simplifications made regarding the molten phase allow to simulate hundreds of thousands of particles, which yield representative electrode microstructures.