Quino Energy ($9M for low-cost aqueous organic redox flow battery for renewable energy storage)

Quino Energy, an American energy storage startup founded in 2021, develops redox flow battery technology using non-flammable, low-cost aqueous electrolytes. The redox active components of electrolytes consist of inexpensive organic quinones and ferrocyanide salts. The Quino Energy flow battery is suitable for renewable energy storage at the grid-scale.

Challenges: Store renewable energy at a low cost

By 2022, the world had about 1,185 GW of installed solar capacity and about 906 GW of installed wind capacity. Solar power has grown at a 24% annual rate over the last decade. The US solar industry installed 6.1 GW of capacity in the first quarter of 2023, 47% more than in the first quarter of 2022. On the other hand, the average power of new wind turbines installed in the US in 2022 was 3.2 MW, 7% higher than in 2021.

As more and more solar cells and wind turbines are installed, the ability to store this clean electricity would significantly increase the efficiency and reliability of these intermittent renewable energy sources.

Flow batteries store and release electrical energy through the movement of electrolytes. A typical flow battery consists of two half-cells separated by a membrane. Each half-cell contains an electrode and an electrolyte. The anolyte and catholyte contain redox-active species dissolved in an aqueous or non-aqueous solvent. They are stored outside of the battery. When the battery is charged or discharged, the electrolytes flow through the half-cells in contact with the electrodes via external pumps.

Flow batteries have an advantage over Li-ion batteries in terms of energy storage duration. By using larger tanks of anolyte or catholyte, it is possible to create longer duration batteries without spending money on an unnecessarily large flow battery stack.

Most flow battery systems are based on vanadium, Fe—Cr, and Zn—Br. They are simple systems and easy to scale up. They can have a long lifespan of more than 20 years. This makes them good candidates for storing renewable energy. However, the capital cost of flow batteries is around $800 per kilowatt-hour, which is more than twice as much as lithium-ion batteries. Therefore, it is necessary to develop cost-effective redox flow batteries.

Quino Energy Technology

Quino Energy has developed a cost-effective redox flow battery system with non-flammable aqueous electrolytes. The aqueous electrolytes are made of inexpensive quinones and ferrocyanide salts. But the quinones in the anolyte can be oxidized over time by reacting with the atmospheric oxygen that gets into the flow battery system through microscopic leaks. This decreases the state of charge (SOC) of anolyte and causes an imbalance between the SOCs of the anolyte and catholyte, thereby reducing the flow battery capacity.

The redox flow battery system developed by Quino features a rebalancing flow cell. This rebalancing flow cell can increase the SOC of the anolyte and rebalance the SOC of both anolyte and catholyte when necessary. Thus, the capacity of the redox flow battery is stable.

Quino Energy redox flow battery

The diagram below depicts the Quino Energy redox flow battery system.

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