Their low energy density makes flow batteries unsuited for mobile or residential applications, but attractive on industrial and utility scale. Hence, they are mostly used commercially or by grid operators in the form of stationary electricity storages ranging from about 40 kWh to. A flow battery is an electrochemical battery, which uses liquid electrolytes stored in two tanks as its active energy storage component. In addition, they are also useful for electric power customers such as factories and office buildings that require increased capacities, uninterrupted supply, or backup power. These electrolytes are stored in external tanks and pumped through a series of electrochemical cells. The energy is stored in the chemical potential difference between the two. Flow batteries, particularly those based on vanadium, have relatively low energy densities when compared to other battery types like lithium-ion batteries. To improve power and energy densities, researchers have started to investigate novel flow battery systems.
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