Due to their comparably high energy density, the most common and technically mature flow batteries use vanadium compounds as their electrolytes. Both, power and energy, possible. Redox flow batteries (RFBs) are gaining significant attention due to the growing demand for sustainable energy storage solutions. For charging and discharging, these are pumped through reaction cells, so-called stacks, where H+ ions pass through a selective membrane from one side to the. As a pioneering manufacturer of cutting-edge long-duration flow batteries, PWRJoule is at the forefront of this innovative technology.