Glow-in-the-dark dyes may soon power cars

Researchers have identified a glow-in-the-dark fluorescent dye which may be an ideal material for stockpiling energy in rechargeable, liquid-based batteries that could one day power cars and homes.

The dye called BODIPY - or boron-dipyrromethene - shines brightly in the dark under a black light.

According researchers from University at Buffalo (UB) in the US, the dye has unusual chemical properties that enable it to excel at two key tasks: storing electrons and participating in electron transfer.

Batteries must perform these functions to save and deliver energy, and BODIPY is very good at them, they said.

In experiments, a BODIPY-based test battery operated efficiently and with longevity, running well after researchers drained and recharged it 100 times.

"BODIPY is a promising material for a liquid-based battery called a "redox flow battery," said lead researcher Timothy Cook, an assistant professor at UB College of Arts and Sciences.

These fluid-filled power cells present several advantages over those made from conventional materials.

Lithium-ion batteries, for example, are risky in that they can catch fire if they break open, Cook said.

The dye-based batteries would not have this problem; if they ruptured, they would simply leak, he said.

Redox flow batteries can also be easily enlarged to store more energy - enough to allow a homeowner to power a solar house overnight, for instance, or to enable a utility company to stockpile wind energy for peak usage times.

This matters because scaling up has been a challenge for many other proposed battery technologies.

When the battery is being used, electrons are harvested from one tank and moved to the other, generating an electric current that - in theory - could power devices as small as a flashlight or as big as a house.

To recharge the battery, you would use a solar, wind or other energy source to force the electrons back into the original tank, where they would be available to do their job again.

A redox flow battery's effectiveness depends on the chemical properties of the fluids in each tank.

"The library of molecules used in redox flow batteries is currently small but is expected to grow significantly in coming years," Cook said.

"Our research identifies BODIPY dye as a promising candidate," he said.

Based on the experiments, scientists also predict that BODIPY batteries would be powerful enough to be useful to society, generating an estimated 2.3 volts of electricity.

The research was published in the journal ChemSusChem.