Electrochemical mechanism in porous electrode of zinc–nickel single-flow battery based on lattice Boltzmann method

•A pore-scale calculation model by LBM is proposed.•The influence of charge current density, flow velocity and porosity is analyzed.•OH− and H+ play a major role in the fluctuation range and the stability of the reaction rate, respectively.•OH− and H+ have a great influence on the overpotential and the reaction current density, respectively. In this study, a two-dimensional numerical model of porous electrodes for zinc–nickel single-flow battery was established based on the structure of porous electrodes for positive electrodes. On this basis, the flow and mass transfer in the porous electrode were simulated using the lattice Boltzmann method. The effects of different charge current densities, electrolyte inlet flow velocity, and porosity on the electrochemical reaction in the porous electrode were analyzed from the perspective of seepage and mass transfer in the pore. The simulation results showed that during the electrochemical reaction, the hydroxide concentration plays a major role in the fluctuation range of the reaction rate, the proton concentration plays a major role in the stability of the reaction rate, and the proton concentration has a relatively large influence on the reaction current density. In addition, the hydroxide concentration has a great influence on the overpotential. The charge current density has a great influence on the electrochemical reaction of the battery. The influence of the electrolyte inlet flow velocity is also negligible.