Temperature Dependence of Capacity Decay due to Ion Diffusion in Vanadium Redox Flow Battery

The need for grid scale energy storage is inevitable in the future. Among all the available battery technologies, Redox Flow Battery (RFB) is one of the most feasible options for large-scale energy storage. Different species of vanadium ions in the battery diffuses at different rates across the membrane and this limits the capacity of the battery over long period of operation. In this paper, the concentration change of different species of vanadium ion is modeled with temperature influence for each of these vanadium ion variants. The concentration change of different vanadium ions due to diffusion is simulated for different temperatures. The change in capacity of the battery is calculated for different temperature profiles and the total loss was partially contributed by intrinsic loss and partly due to diffusion. It was also observed that the difference in the loss at different temperatures is higher during the initial 50% of the total lifecycle and stabilizes as it proceeds. At the end of 200 cycles, the capacity loss at 40 degrees C was higher (14.23%) than that of 30 degrees C (13.37%) and 20 degrees C (12.67%) of which a major part was contributed due to diffusion in the first 100 cycles of operation.