Vitamin B2 helps to store energy from food in the body. This characteristic led researchers to investigate whether or not it could be used to create batteries. Using organic molecules to store energy is not a new idea. Harvard researchers have previously used molecules called quinones and a food additive called ferrocyanide to develop a high-capacity flow battery.

As flow batteries store energy in solutions in external tanks, they have a huge drawback. The more energy you want to store, the bigger your tank has to be. In conventional batteries, metal ions are used for the electrolytes. As quinone molecules store energy in plants and animals, the previous research team replaced the metal ions with a specific quinone that could work in alkaline solutions in 2015. A common food additive was also added to the mix to enhance performance.

Although flow batteries work well with the versatile quinones, Harvard researchers persistently explored other organic molecules in an effort to achieve even better performance. Finding other organic systems with the same versatility proved challenging.

Kaixiang Lin, a Ph.D. a student at Harvard and the first author of the latest new research paper noted that they considered about a million different quinones before they managed to develop a new class of battery electrolyte material that expands the possibilities of what could be done. An important goal of this project was that manufacturing of the new batteries should be possible at a very low cost on a large scale. The simple synthesis of the new vitamin B2 based organic molecules is a distinct advantage over quinones, and this makes low cost production possible.

While quinones use oxygen atoms to pick up and give off electrons, B2 uses nitrogen atoms. The result is that a new group of molecules becomes a good contender for alkaline flow batteries with only a few tweaks to the original B2 molecule. Unlike quinones, vitamins are very easy to manufacture, making it possible to manufacture the new molecule on a large scale at a very low cost.

Gordon, co-senior author of the paper, remarks that nature actually pointed to this way to store energy, as similar molecules are vital in storing energy in our bodies.

This result is a game-changer. Large-scale, inexpensive electricity storage is now possible using low-cost chemicals that are non-toxic, non-flammable, non-corrosive and high performing. It is now possible to manufacture large batteries that can safely store electricity from irregular energy sources like wind power and solar.

The team will continue to explore this new universe of molecules in search of a high-performing, long-lasting but inexpensive flow battery.

The new research is published in journal Nature Energy.

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