'Self-heat' could help batteries power up energy grid in extreme cold

An international research team led by Senior Research Scientist Mikhail Pugach has developed a non-isothermal dynamic model to explain how large-scale vanadium redox flow batteries can maintain stable operation in cold climates. These batteries, crucial for storing energy from intermittent renewable sources like wind and solar, face performance degradation in low temperatures due to increased electrolyte viscosity, which slows circulation and reduces capacity. The study reveals that under high load currents, the batteries generate heat internally—raising electrolyte temperature by over 15°C across multiple charge-discharge cycles—thereby stabilizing flow and capacity through a self-heating mechanism. The model accurately predicts key battery parameters such as voltage, ion concentrations, temperature, and power output, validated against experimental data from 9 kW and 35 kW battery systems with less than 1% error. It also evaluates two operating modes in cold conditions: a constant pump power mode, which allows natural electrolyte heating but initially reduces capacity without extra energy use, and a constant flow rate mode