Non-Aqueous All-Organic Redox Flow Battery

May 15, 2023

Scientists at the Indian Institute of Technology, Madras (IIT-M), have made significant strides in battery technology with their development of the non-aqueous all-organic redox flow battery.

Advantages of Flow Batteries: Energy Storage Without Space Constraints

Flow batteries have gained popularity in various industries, particularly in solar and wind farms, grid stability, and replacing diesel gensets. One of the key advantages of flow batteries is their ability to store energy without space constraints. Unlike conventional batteries, which rely on solid electrodes, flow batteries store energy in liquid redox electrolytes. By increasing the size of the tanks that hold these electrolytes, the energy storage capacity can be expanded infinitely.

Challenges with Conventional Flow Batteries: Aqueous Electrolytes and Drawbacks

Conventional flow batteries utilize aqueous electrolytes such as hydrochloric acid, sulfuric acid, and alkali metal hydroxides. However, these electrolytes present two significant challenges:

Water in the electrolyte undergoes electrolysis, reducing the operating voltage limit and energy density.
The presence of water leads to corrosion of battery components, diminishing their lifespan and performance.

IIT-M’s Breakthrough: Non-Aqueous All-Organic Flow Battery

To address the limitations of conventional flow batteries, the team of scientists at IIT-M developed a new type of flow battery known as the non-aqueous all-organic redox flow battery (NORFB). This innovative battery incorporates non-aqueous and organic electrolytes, eliminating the issues caused by water in conventional flow batteries.

The Role of Pyrylium Salts: Enabling High-Voltage Operation and Energy Storage

The researchers at IIT-M utilized pyrylium salts, a class of organic chemicals, to create a new type of electrolyte for their flow battery. With suitable structural modifications, these chemicals enable high-voltage operation, allowing the battery to store more energy efficiently. Additionally, the chosen electrolytes offer advantages such as high solubility, reversibility, and cost-effectiveness.

Anolyte and Catholyte Materials: Enhancing Battery Performance

In the IIT-M flow battery, the anolyte material used is 2-, 4-, 6-triphenylpyrylium tetrafluoroborate, while N-decylphenothiazine serves as the catholyte material. These materials, coupled with the non-aqueous all-organic electrolyte, contribute to the battery’s enhanced performance, high current densities, and improved stability.

Exceptional Coulombic Efficiency: A Promising Result

Through their research, the scientists achieved an average coulombic efficiency of 97% with the IIT-M flow battery. This efficiency indicates the effectiveness of the battery in converting and storing electrical energy.

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