Pore-scale investigation of ion transport in a fibrous electrode of a desalination battery based on lattice Boltzmann method

Abstract

The fibrous electrode has gained much attention because of its larger specific surface area and shorter ion transport path than other morphological electrodes. In this paper, a random reconstruction method for fibrous electrode is proposed to generate a two-dimensional fibrous electrode, a study of kinetic processes inside electrode of dual-ion electrochemical deionization system was conducted based on the lattice Boltzmann method. The concentration distribution of sodium ion inside fibers and pores of electrode in the process of desalination was revealed, the influence of different microstructures (fiber diameter, fiber orientation, electrode porosity) and initial parameters (inlet flow rate and initial concentration of electrolyte) during the process were evaluated. The results indicate that the sodium ions can be embedded inside the fibers faster when the fiber is oriented perpendicular to the flow direction of the electrolyte. Smaller diameter of fiber and higher porosity of electrode can increase the rate of desalination, but the cost of increasing porosity is a reduction in total amount of desalination. By raising the initial concentration and inlet flow rate of electrolyte, the rate of desalination can be improved, but too high a flow rate will reduce the rate of reaction.