Even today's best rechargeable lithium batteries do lose their ability to hold a charge after a while, and are considered toxic waste once discarded. In just a few years, however, they may be replaced by batteries that are refillable and biodegradable, and that will also have a higher energy density yet a lower price ... and they'll run on sugar.

"Sugar is a perfect energy storage compound in nature," says Virginia Tech's Prof. Y.H. Percival Zhang, who is leading the research. "So it's only logical that we try to harness this natural power in an environmentally friendly way to produce a battery."

Zhang's isn't the first experimental sugar battery, although he claims that its energy density is "an order of magnitude higher than others."

It's actually a type of enzymatic fuel cell. For fuel, it utilizes maltodextrin, which is a polysaccharide made from the hydrolysis of starch (polysaccharides are chains of sugars). The catalyst in its anode is made from inexpensive enzymes, as opposed to the costly platinum that's used in regular batteries.

When the maltodextrin is combined with air, water and electricity are produced. Unlike the case with a hydrogen fuel cell, however, the sugar battery is non-explosive and non-flammable.

Zhang envisions users refilling the batteries with sugar when they need refueling, "much like filling a printer cartridge with ink." He hopes that they may be powering electronic devices in as little as three years.

A paper on his research was published today in the journal Nature Communications.