Lattice Boltzmann model for complex transfer behaviors in porous electrode of all copper redox flow battery with deep eutectic solvent electrolyte

Deep eutectic solvents (DESs) as temperature sensitive non-aqueous electrolytes have been proposed to elevate the energy density of redox flow batteries (RFBs). In this paper, a pore scale multiple-relaxation-time (MRT) lattice Boltzmann (LB) model is established to predict the electrolyte flow, species/charge transfer behaviors and electrochemical reaction in the porous electrode of all copper RFB with DES electrolyte at the different operating temperature. The effects of morphological characteristics of reconstructed porous electrode and transport properties of DES on the RFB performance during charging are investigated using this LB model. The numerical results suggest that the decreasing porosity results in a higher electrolyte utilization efficiency at the same required pumping power, and reduces the average overpotential under the galvanostatic charging condition. The operating temperature plays a key role in the operation of RFB with DES electrolyte. The flow rate of DES electrolyte are improved sufficiently by the increasing operating temperature. Meanwhile, the average over-potential diminishes observably as the elevated operating temperature. In addition, the higher operating temperature also improves the uniformity of local transfer current density especially when the operating temperature is lower than 313 K.