Battery takes advantage of nature's energy store

Batteries that take advantage of nature’s energy storage medium are nothing new, but the one described in the journal Nature Communications today has an energy density an order of magnitude higher than others said its inventor, Virginia Tech's Professor Y H Percival Zhang.

This higher energy density allows it to run longer before needing to be refuelled, according to Prof Zhang, and he predicts that the battery could be running energy-hungry portable devices such as cell phones and tablets in as little as three years.

"Sugar is a perfect energy storage compound in nature," Prof Zhang said. "So it's only logical that we try to harness this natural power in an environmentally friendly way to produce a battery."

As with all fuel cells, the sugar battery combines fuel – in this case, maltodextrin, a polysaccharide made from partial hydrolysis of starch – with air to generate electricity and water as the main by-products.

Where the battery differs from the better known hydrogen fuel cells and direct methanol fuel cells, the fuel sugar solution is neither explosive nor flammable and has a higher energy storage density.

The device relies on a synthetic enzymatic pathway created by Prof Zhang and his colleagues that strips all charge potentials from the sugar to generate electricity with low-cost biocatalyst enzymes used as a catalyst instead of costly platinum, which is typically used in conventional batteries.

"We are releasing all electron charges stored in the sugar solution slowly step-by-step by using an enzyme cascade," Prof Zhang said.

Importantly, both the enzymes and fuels used to build the device are biodegradable and the battery is refillable – sugar can be added to it much like filling a printer cartridge with ink.

If the battery is eventually commercialised, Prof Zhang said it could help keep hundreds of thousands of tonnes of toxic batteries from ending up in landfill.