Scientists from Skoltech, Harbin Institute of Technology, and MIPT have conducted a study on the operation of an energy storage system based on a vanadium redox flow battery across an extended range of ambient temperatures. To achieve this, the researchers developed a mathematical model of the vanadium redox flow battery capable of describing its dynamic behavior under different temperatures — from 5 to 40°C — and various operating parameters.
The results, published in the Journal of Power Sources, will serve as the foundation for developing advanced battery management algorithms that maintain maximum system efficiency even in low-temperature conditions. Furthermore, the model can also be applied to other types of flow batteries and fuel cells. The work received support from the Russian Science Foundation (project No. 23-79-01239).
Flow batteries are primarily used in large-scale energy systems designed for long-term electricity storage to support autonomous power supply and ensure stable and reliable grid operation. Moreover, such large-scale systems help address a critical challenge associated with renewable energy sources — fluctuations in frequency and power. They provide stable power supply to the grid by smoothing out generation variability.
Energy storage systems typically occupy large areas and are often installed outdoors. This exposes them to seasonal temperature variations, which affect key performance metrics such as energy efficiency, power, and capacity. Therefore, studying the impact of ambient temperature on the operation of such energy storage systems is a crucial practical task for ensuring their reliable and stable performance across a wide range of climatic conditions.
“We developed a non-isothermal dynamic model of the vanadium flow battery based on the laws of energy and mass conservation. The model accounts for the temperature dependence of electrolyte viscosity and allows for the simulation of various hydraulic properties of the energy storage system at different operating temperatures. It also predicts changes in key parameters of the vanadium redox flow battery, including voltage, vanadium ion concentrations, stack and tank temperatures, pressure drop, electrolyte flow rate, capacity, and power,” explained the group leader Senior Research Scientist Mikhail Pugach from the Skoltech Energy Center.
“We validated the model using experimental data obtained from two large-scale vanadium redox flow batteries with powers of 9 kW and 35 kW. The model demonstrated high accuracy in predicting electrolyte temperature, output voltage, and system pressure losses (with an error of less than 1%). We then applied the model for parametric analysis of a 5 kW system under various electrolyte flow rates (from 4 to 16 L/min), load current densities (from 20 to 140 mA/cm²), and ambient temperatures (from 5 to 25°C). The results showed that at low ambient temperatures, electrolyte viscosity increases significantly, slowing its circulation within the system. This, in turn, leads to substantial capacity loss due to increased concentration losses and enhanced electrolyte conversion. However, at high load currents (above 95 mA/cm²), the electrolyte temperature can rise by more than 15°C over 10 charge-discharge cycles, stabilizing flow and capacity. In other words, through self-heating, the battery can operate stably even under low ambient temperatures,” shared Stanislav Bogdanov, the first author of the paper and a junior research scientist at the Skoltech Energy Center.
The authors analyzed capacity and power losses in two operating modes of the vanadium redox flow battery: constant flow rate and constant pump power. In the constant flow rate mode, significant power losses — up to 10% — were observed in the initial cycles, caused by intensive pump operation due to high electrolyte viscosity. The constant pump power mode avoids system power losses; however, in this case, reduced battery capacity is observed in the initial cycles at low ambient temperatures. After several cycles, the electrolyte heats up, and capacity levels recover.
The research enables the identification of optimal operating conditions for vanadium redox flow batteries in various climates and temperatures. Understanding the impact of temperature on performance and durability will help design systems resilient to adverse operating conditions, while regulating battery operating parameters will prevent premature wear and reduce the likelihood of failures.
