The effect of flow rate and concentration on the electrical conductivity of slurry electrodes using a coupled computational fluid dynamic and discrete element method (CFD–DEM) model

Abstract

Slurry electrodes are used in a variety of electrochemical systems and offer a number of advantages compared to solid electrodes. Because of the many variables associated with slurries, such as particle size, shape, conductivity and concentration, their properties are not sufficiently well understood. This research aims to find out how the carbon particles suspended in a slurry electrode participate in the charge transfer process and how the charge transfer process is affected by the flow rate. For this purpose, we simulate slurry electrodes by utilising a coupled Computational Fluid Dynamic and Discrete Element Method (CFD–DEM) technique to analyse the dynamic and hydrodynamic forces resulting from the exchange of momentum between the particles and the electrolyte. For the first time, we simulate the effects of Brownian motion on charge transport. Additionally, by introducing a charge transfer efficiency coefficient into the model, the effects of added electrical resistance due to the electrolyte and particle contacts are simulated. The obtained results show that, with a parallel plate electrode configuration, the electric conductivity of the slurry electrode decreases with increased velocity in the creeping flow regime. We show how increasing the particle concentration increases the electric conductivity of the electrode. Our study demonstrates that particle–wall interactions make a much larger contribution to the resistance than particle–particle interactions. The electric conductivity calculated in the present study is compared with previous experimental and numerical studies, showing good agreement.

Keywords

• Slurry electrode
• Carbon particle
• CFD–DEM method
• Brownian motion
• Charge transfer efficiency coefficient
• Electric conductivity