A team of researchers at the University of Toronto, Canada, has created a battery that stores energy in a biologically derived unit. The team’s paper outlining the discovery was published July 14 in the journal Advanced Functional Materials.

The new battery is similar to many commercially-available lithium-ion batteries with one important difference – it uses flavin from vitamin B 2 (riboflavin) as the cathode, the part that stores the electricity that is released when connected to a device.

“We’ve been looking to nature for a while to find complex molecules for use in a number of consumer electronics applications,” said senior author Dr. Dwight Seferos, from the University of Toronto’s Department of Chemistry.

“When you take something made by nature that is already complex, you end up spending less time making new material.”

While bio-derived battery parts have been created previously, this is the first one that uses bio-derived polymers – long-chain molecules – for one of the electrodes, essentially allowing battery energy to be stored in a vitamin-created plastic, instead of expensive, harder to process, and more environmentally-harmful metals such as cobalt.

“Getting the right material evolved over time and definitely took some test reactions,” said co-author Tyler Schon, also from the University of Toronto’s Department of Chemistry.

“In a lot of ways, it looked like this could have failed. It definitely took a lot of perseverance.”

The scientists happened upon the material while testing a variety of long-chain polymers – specifically pendant group polymers: the molecules attached to a ‘backbone’ chain of a long molecule.

They created the material from vitamin B 2 that originates in genetically-modified fungi using a semi-synthetic process to prepare the polymer by linking two flavin units to a long-chain molecule backbone.

“It’s a pretty safe, natural compound. If you wanted to, you could actually eat the source material it comes from,” Dr. Seferos said.

Lithium-ion batteries incorporating this material have a 125 mAh/g capacity and a 2.5 V operating potential.

“We show that this polymer provides a capacity of 125 mAh/g with a voltage of 2.5 V in a device using lithium metal as the anode material,” the researchers said.

“We also demonstrate that this material has a much higher performance than the small molecule riboflavin.”

“This is the highest capacity reported for bio-derived polymeric cathodes.”

Vitamin B 2 ’s ability to be reduced and oxidized makes its well-suited for a lithium ion battery.

“B 2 can accept up to two electrons at a time. This makes it easy to take multiple charges and have a high capacity compared to a lot of other available molecules,” Dr. Seferos said.

While the current prototype is on the scale of a hearing aid battery, Dr. Seferos and his colleagues hope their breakthrough could lay the groundwork for powerful, thin, flexible, and even transparent metal-free batteries that could support the next wave of consumer electronics.

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Tyler B. Schon et al. Bio-Derived Polymers for Sustainable Lithium-Ion Batteries. Advanced Functional Materials, published online July 14, 2016; doi: 10.1002/adfm.201602114