Electrolytes are stored externally in tanks, while the electrochemical cell handles energy conversion. Flow batteries have two main categories: Redox flow batteries utilize redox reactions of the electrolyte solutions for energy storage.
John Katsoudas, a founder and chief executive of Influit, emphasizes the distinction between his company’s design and a conventional flow battery. “Our novelty is in doing what others have already done [with flow batteries] but doing it with nanofluids,” he says.
A typical flow battery has been shown in Fig. 8. Some of the main characteristics of flow batteries are high power, long duration, and power rating and the energy rating are decoupled; electrolytes can be replaced easily . Fig. 8. Illustration of flow battery system [133,137]. Zhibin Zhou, ...
An aqueous flow battery with inexpensive carbon electrodes, combining the quinone/hydroquinone couple with the Br2/Br− redox couple, yields a peak galvanic power density exceeding 0.6 W cm−2 at 1.3 A cm−2. Cycling of this quinone–bromide flow battery showed >99 per cent storage capacity retention per cycle.
The battery will store 800 megawatt-hours of energy, enough to power thousands of homes. The market for flow batteries—led by vanadium cells and zinc-bromine, another variety—could grow to nearly $1 billion annually over the next 5 years, according to the market research firm MarketsandMarkets.
In contrast with conventional batteries, flow batteries store energy in the electrolyte solutions. Therefore, the power and energy ratings are independent, the storage capacity being determined by the quantity of electrolyte used and the power rating determined by the active area of the cell stack.