Using strands of vitamin B2 that originated in genetically-modified fungi, researchers at the University of Toronto (U of T) have developed a battery with high capacity and high voltage that may pave the way for environmentally-friendly, metal-free batteries. Claimed by the researchers to be comparable to existing high-energy lithium-ion batteries, with a capacity of around 125 mAh and a 2.5 V potential, the U of T unit uses flavin derived from vitamin B2 as the battery's cathode rather than a lithium-based material.
"We've been looking to nature for a while to find complex molecules for use in a number of consumer electronics applications," says Dwight Seferos, an associate professor in the U of T department of chemistry. "When you take something made by nature that is already complex, you end up spending less time making new material."
While other research, such as the flow cell from Harvard University, has incorporated vitamin B2 as part of a battery, the U of T researchers claim that their derivative is the very first to use long-chain molecules of bio-derived polymers for one of the electrodes, thereby storing energy in a plastic created from vitamins, rather than metals that are more expensive, harder to process, and potentially more toxic to the environment.
Researching a variety of long-chain polymers – in particular, pendant group polymers that are a group of molecules found attached to a "backbone" chain of lengthier molecules – the U of T chemists created their new cathode material by linking two flavin units to a long-chain molecule backbone.
"Organic chemistry is kind of like Lego," said Serefos. "You put things together in a certain order, but some things that look like they'll fit together on paper don't in reality. We tried a few approaches and the fifth one worked."
The inherent ability of vitamin B2 to store energy in our bodies from the breakdown of foods also means that it is easily reduced and oxidized in operation, making it ideal for use in a rechargeable battery.
"B2 can accept up to two electrons at a time," said Seferos. "This makes it easy to take multiple charges and have a high capacity compared to a lot of other available molecules."
"It's been a lot of trial-and-error," added Schon. "Now we're looking to design new variants that can be recharged again and again."
Though the U of T prototype is only around the size of a conventional hearing aid battery, the researchers are hopeful that their new device may pave the way for metal-free batteries that are more energy-efficient, thinner, and with greater flexibility than those available today. The team also believes that a completely transparent version could one day be created using their flavin polymer technique.
The results of this research were recently published in the journal Advanced Functional Materials.
Source: University of Toronto
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