flowbattery

A flow battery is a type of electrochemical cell where energy is stored in liquid electrolytes that are pumped through the system. Unlike conventional batteries, the energy storage capacity of a flow battery is independent of its power output. This is because the energy is stored in external tanks containing the electrolyte, allowing for scaling of energy capacity by simply increasing the size of the tanks. The power output is determined by the size of the electrochemical stack where the reactions occur.

Flow batteries operate by circulating two liquid electrolytes through an electrochemical cell. One electrolyte contains the oxidized species, and the other contains the reduced species. During charging, electrical energy is used to drive a chemical reaction that converts the electrolyte into a higher energy state. During discharging, the process is reversed, and the chemical energy is converted back into electrical energy. Common chemistries include vanadium redox, zinc-bromine, and iron-chromium.

The primary advantages of flow batteries include their long lifespan, ability to perform deep cycling without significant degradation, and inherent safety due to the separation of energy storage from power conversion. They are also well-suited for large-scale applications such as grid energy storage, where the need for extended discharge durations is common. However, their lower energy density compared to some other battery technologies can be a limitation for mobile applications. The complexity of pumping systems and the cost of electrolytes can also be considerations.