Researchers create stable kilowatt-scale aqueous organic flow batteries

• Flow batteries (FBs) are assuring in large-scale energy storage because of their high protection and efficiency. Amongst them, aqueous organic flow batteries (AOFBs) that utilize structural tunable as well as eco-friendly redox-active molecules are getting raised attention.

Nevertheless, most organic molecules in AOFBs are prone to be oxidized particularly by air, causing irreversible capacity decay and also hindering their additional applications.

Just recently, a research study team led by Prof. Li Xianfeng and also Prof. Zhang Changkun from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS) has created stable kilowatt-scale AOFB stacks with high-performance organic redox-active molecules.

This research was released in Energy & Environmental Science on Dec. 1.

The researchers revealed the stabilization system of one redox-active molecule, methylene blue (MB), as well as showed that the stabilizations of MB, specifically in both intermediate free radical state and also minimized state, played a vital role in enhancing redox reversibility and also air-stability.

They monitored MB by in-situ nuclear magnetic vibration (NMR) and found that free radicals were created by comproportionation reactions between oxidized and also lowered states in the electrolyte.

" We optimized electrolyte composition by tuning the interaction between different components in the electrolyte, consequently boosting the battery capacity," stated Prof. Li.

What's even more, the researchers showed that oxidation resistance of MB radicals and also reduced states played an essential role in boosting redox reversibility as well as air-stability by incorporating ex-situ electron paramagnetic vibration (EPR) with academic computation.

To further validate the usefulness of MB molecule in AOFBs, they assembled 10 units of 1000 cm2 AOFBs stacks. "We obtained the stacks with a discharge power of over 1 kW and a stable cycling capacity for 32 days," claimed Prof. Zhang. "Our research study may give an essential recommendation for the AOFB sensible application."