Impact of Screw Geometry and Solids Content on the Properties of Continuously Produced Si Anodes

Abstract

Within the realm of lithium‐ion batteries, there is a growing emphasis on achieving high energy density and environmentally friendly production at a low cost. To address these demands, the battery slurries in this study incorporate the high‐energy anode material silicon. They are systematically produced through continuous extrusion, aiming to realize cost reductions by significantly reducing the overall process time. In this study, it is demonstrated that the choice of screw configuration and solids content during kneading influences the specific energy input and the stress intensity during processing significantly. The stress intensity, represented here by the specific torque, has a great influence on the slurry properties as well as the electrochemical performance of the battery. An increased stress intensity leads to an increase in adhesive strength and ionic resistance. In the results, it is indicated that carbon black decomposition increases significantly, but when a critical specific stress intensity in form of the specific torque is reached, delamination and fracture of the graphite particles occur, leading to a loss of lithium‐ion storage capacity, favoring lithium plating and severely degrading both capacity by up to 40% at 1C and long‐term performance by up to 10% after 50 cycles.