An extensive scaling-up oriented investigation on carbon felt flow-through and interdigitated Vanadium Flow Batteries cells

A 3D multiphysics full-cell model for Vanadium Flow Batteries (VFBs) was developed and validated, enabling precise computational predictions of battery performance. Several innovations are proposed, such as a novel numerical formulation for membrane modeling, based on an internal boundary condition to ensure numerical robustness and mesh efficiency, improving solver stability. Parameters such as electrode permeability, conductivity, and contact resistance were determined experimentally, while electrolyte density and viscosity were calculated using novel empirical formulations. The accuracy of the model was within 2 %. A total of 90 3D simulation cases were evaluated with interdigitated flow-by (IDFF) configurations in a 50 cm 2 cell, by varying the number and width of the channels and compared to a flow-through (FTFF) benchmark. The FTFF setup demonstrated superior performance in a wider operating conditions range, achieving peak power up to 6 % higher than IDFF at 50 mL min -1 . Conversely, IDFF cells exhibited potential for higher peak power, up to 10 %, when operated at limiting pressure conditions as those of industrial-scale VFB stacks. This model, validated against both electrochemical and hydraulic experiments, elucidate the fluid dynamics and electrochemical interplay in FTFF and IDFF configurations enables the exploration of flow field effects under industrially relevant constraints.