Pre-magnetization smashing hydrated vanadium ions to improve redox flow batteries performance

The vanadium redox flow battery (VRFB) has received extensive attention due to its intrinsic safety and high scalability. Currently, there are still deficiencies of low energy efficiency and higher unit capacity cost in VRFB energy storage. Continuously optimizing the battery performance through reducing electrode polarization losses is a necessary way to achieve efficient VRFB energy storage technology. In this study, a method of pre-magnetizing the electrolyte to improve the performance of the battery was proposed. A permanent magnet with an intensity of 0.9 T was used to pre-magnetize the vanadium-ion aqueous electrolyte before feed into the battery stack and working-on, it was found that the diffusion capacity of vanadium ions increased by 133.6 % after pre-magnetized even if the external magnetic field was removed. Meanwhile, both of the charge transfer and concentration polarization resistance of the electrode were reduced. The energy efficiency (EE) of the battery was increased by 6.4 % in the charge–discharge test at current density of 300 mA cm⁻². The power density increased by 6.19 % with current density 400 mA cm⁻² at most, and it prefers to continuously increase as current larger. The electrolyte pre-magnetization showed significant positive improvements on the electrode reaction kinetics and battery charge–discharge cycle.