Numerical optimization of magnetic field application scheme for deep eutectic solvent (DES) electrolyte flow battery

Abstract

In this paper, MATLAB was used for parameter fitting and the finite element method was used to construct a three-dimensional redox flow battery model. Using this model, the effect of magnetic field was coupled to the flow of electrolyte, mass transfer, and electrode kinetics equations in the form of fitting functions, and the mechanism of magnetic field in the iron-vanadium DES flow battery was explored. The simulation results showed that as the magnetic field increased from 0 mT to 605 mT, the average overpotential inside the electrode was decreased, the distribution of ions on the membrane side became more uniform, the output voltage of the battery was increased, and the energy conversion efficiency of the charging and discharging cyclins was improved. Meanwhile, the Lorentz force exerted on the ions by the magnetic field is transferred to the fluid, which reduces the viscosity of the DES, thereby reducing the resistance to flow of the electrolyte and promoting a more uniform flow of the electrolyte. Subsequently, based on the structure and ion motion direction of the redox flow battery, the effect of dual N-pole placement on the battery performance was investigated numerically in this work, and comparing with the N–S pole scheme, the maximum current density was increased by 7.13%, and the charging and discharging energy conversion efficiency was also improved.