Environmentally-friendly battery is long-lasting and high voltage
A team of University of Toronto chemists has created a battery that stores energy in a biologically-derived unit, paving the way for cheaper consumer electronics that are easier on the environment.
The battery is similar to many commercially-available high-energy lithium-ion batteries with one important difference. It uses flavin from vitamin B2 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,” says Dwight Seferos, an associate professor in U of T’s department of chemistry and Canada Research Chair in Polymer Nanotechnology.
“When you take something made by nature that is already complex, you end up spending less time making new material,” says Seferos.
Background battery basics
To understand the discovery, it’s important to know that modern batteries contain three basic parts:
- a positive terminal – the metal part that touches devices to power them – connected to a cathode inside the battery casing
- a negative terminal connected to an anode inside the battery casing
- an electrolyte solution, in which ions can travel between the cathode and anode electrodes
When a battery is connected to a phone, iPod, camera or other device that requires power, electrons flow from the anode – the negatively charged electrode of the device supplying current – out to the device, then into the cathode and ions migrate through the electrolyte solution to balance the charge. When connected to a charger, this process happens in reverse.
The reaction in the anode creates electrons and the reaction in the cathode absorbs them when discharging. The net product is electricity. The battery will continue to produce electricity until one or both of the electrodes run out of the substance necessary for the reactions to occur.
Organic chemistry is kind of like Lego
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 costlier, harder to process, and more environmentally-harmful metals such as cobalt.
“Getting the right material evolved over time and definitely took some test reactions,” says paper co-author and doctoral student Tyler Schon. “In a lot of ways, it looked like this could have failed. It definitely took a lot of perseverance.”
Schon, Seferos and colleagues 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.
“Organic chemistry is kind of like Lego,” he says. “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,” says Seferos.
Building a better power pack
The team created the material from vitamin B2 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.
This allows for a green battery with high capacity and high voltage – something increasingly important as the ‘Internet of Things’ continues to link us together more and more through our battery-powered portable devices.
“It’s a pretty safe, natural compound,” Seferos adds. “If you wanted to, you could actually eat the source material it comes from.”
B2’s ability to be reduced and oxidized makes its well-suited for a lithium ion battery.
“B2 can accept up to two electrons at a time,” says Seferos. “This makes it easy to take multiple charges and have a high capacity compared to a lot of other available molecules.”
A step to greener electronics
“It’s been a lot of trial-and-error,” says Schon. “Now we’re looking to design new variants that can be recharged again and again.”
While the current prototype is on the scale of a hearing aid battery, the team hopes 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.
The team’s paper outlining the discovery appeared in the July issue of Advanced Functional Materials.
Transporting power sources in the coldest places may be easier with a new re-chargeable, non-metallic battery from Japan. This “eco battery” could provide portable sources of power in environments like refrigerated factories or extreme winter environments.
Chemists from Hiroshima University developed a new synthesis method for organic radical batteries that are re-chargeable and continue to function at below-freezing temperatures. The specific model prototyped by the Hiroshima University team has greater voltage than previously reported styles from other research groups around the world. The method used to create this battery is an improvement on a report from the same Hiroshima University laboratory earlier in 2016.
Most electrical devices use a lithium-ion battery. Lithium-ion batteries are safer than standard lithium metal batteries, but both styles rely on metal, a finite resource that is in decreasing supply. The same problem of decreasing supply exists for copper and cobalt batteries, like the traditional AA batteries in TV remote controls.
Organic radical re-chargeable batteries have the potential to be cheaper, safer, and longer-lasting than current metal-based batteries, earning them the “eco battery” title. This style of battery can re-charge faster than meal-based batteries, the difference of one minute instead of one hour, because they carry energy chemically rather than physically.