An Unsteady Model to Study the Effects of Porosity and Temperature in All-Vanadium Redox Flow Battery with Mass Transfer and Ion Diffusion

Abstract

The crossover of vanadium ions through membrane in vanadium redox flow battery after many cycles leads to capacity loss of the cell. Different membrane materials show different diffusion behavior which results in variation in the cell potential response. The diffusion coefficients of the membrane is temperature dependent, therefore, concentration profile varies with temperature. The model has considered the effects of crossover of vanadium ions through membrane and mass transfer. The present model predicts the capacity loss for different membrane materials. The simulation results show that reaction rate constants and diffusion coefficients depend on temperature and these affect the cell performance. The results show that for Selemion AMV and Selemion CMV membranes capacity loss increases linearly at different temperatures and porosity with increase in number of cycles. In the case of Nafion 115 membrane the capacity decays up to 77 cycles and then it stabilizes.