Unit Cell Modelling and Simulation of All Vanadium Redox Flow Battery

Vanadium redox flow battery (VRFB) is one of the promising technologies for large scale renewable energy storage due to its long life time and flexible design. Electrolyte flow rate, electrolyte concentration, electrode porosity, temperature and applied magnitude of current have significant effect on the efficiency of VRFB. In the present work, a simplified dynamic lumped parameter model is developed in MATLAB to provide accurate results at unit cell level which can be used to control and optimize the parameters. The proposed model is based on the mass balance and charge conservation of various vanadium species and hydrogen ion concentration in the electrolyte. Major losses such as ohmic losses and activation losses are included in the cell potential. Recirculation of the electrolyte through external reservoirs is also considered. Numerical simulation demonstrates the effect of change in initial vanadium concentration and operating temperature on unit cell performance. It is shown that variations in electrolyte flow rate, magnitude of applied current substantially alter the charge/discharge characteristics and efficiency.