Dual-mode thermal management of vanadium redox flow battery electrolyte tanks under extreme-temperature conditions

To address the coupled thermal management requirements under both low- and high-temperature conditions, a dual-mode temperature control system was developed for vanadium redox flow battery electrolyte tanks. The system integrates double-layer vacuum insulation, interlayer liquid cooling, and rotary stirring-assisted heating. Comparative experiments over a temperature range of − 40 to 60 °C were conducted and supplemented by COMSOL heat-transfer simulations. During low-temperature insulation tests at − 20 to − 40 °C, the proposed system limited the electrolyte temperature decrease to 24.6–32.4 °C, whereas the conventional system exhibited decreases of 40.3–51.5 °C. In heating mode, the proposed system shortened the heating time by 77 %–83 % and reduced energy consumption by 44 %–58 %. Rotary stirring also improved the temperature uniformity of the electrolyte. Under high-temperature conditions of 40–60 °C, interlayer liquid cooling rapidly reduced the electrolyte temperature to 27 °C and maintained stable thermal conditions, significantly outperforming natural heat dissipation. Single-cell cycling tests conducted at − 20 °C further demonstrated that the proposed system improved the coulombic, voltage, and energy efficiencies over a range of flow rates and current densities compared with the conventional system.