An Electro-Thermal Coupled Model of Vanadium Redox Flow Battery for Large-scale Energy Storage System

The temperature of vanadium redox flow batteries (VRBs) plays an important role on the electrical characteristics, energy efficiency and safe operation. The lost energy of the VRBs will eventually dissipate in the form of heat and lead to temperature rise. Previous studies often neglected the electro-thermal coupled relationship, which could not reflect the change of battery temperature accurately. In this paper, an electro-thermal coupled model of VRBs is proposed. The second-order RC circuit is adopted to characterize the overpotential characteristics, and the impact of shunt current and ion diffusion is considered. A dynamic model describing thermal behavior was set up based on a second-order Cauer network. The Trust Region algorithm is used to identify the model parameters. Experiments under constant current and pulse charging and discharging currents were carried out based on a 5kW/3kWh battery experimental platform. The results show that this model can reflect the coupled relationship between temperature and the dynamic electrical behavior accurately under different operation. The model proposed is also applicable for battery operation optimization.