In battery cell production, electrolyte filling is one of the most time-consuming steps, thus limiting the overall throughput of cells being manufactured. Since electrolyte filling takes place in an opaque cell enclosure, analysis of the processes and corresponding mechanisms requires hugh experimental effort. As a result, the cause-effect relationships are poorly understood. Thus, simulative observation of electrolyte filling is a promising and powerful method that allows to gain insights in this hardly accessible process. The process of electrolyte filling operatively comprises two subprocesses, filling and wetting. There are simulative approaches for both sub-processes in the scientific literature. An analysis of the simulation studies shows that the focus is on micro-simulations of the wetting sub-process. The least represented simulation is the macro simulation of the filling sub-process.
Within this work, the filling sub-process for large prismatic battery cells (300*100*30 mm) was studied using macroscopic CFD simulation (Ansys Fluent). The effect of crucial process parameters for electrolyte filling like dosing or cell pressure on the electrolyte filling behavior and duration was examined. There is a positive linear correlation between the differential pressure (dosing pressure – cell pressure) and the filled volume fraction in the battery cell. In addition, the investigations of alternative process designs such as multiple filling holes show that the use of several dosing needles for electrolyte filling is advantageous, as significantly faster filling can be observed with two inlets compared to one inlet. Further studies will additionally investigate the influ-ences of the material properties and shift the focus to the simulation of macroscopic wetting with the “FLUID” software, as the added value of further studies on macroscop-ic filling is limited.