A Virginia Tech research team led by Dr. Y.H. Percival Zhang has developed a high-energy-density sugar “biobattery”—a sugar-fueled fuel cell based on a synthetic enzymatic pathway. This enzymatic fuel cell is based on non-immobilized enzymes that exhibit a maximum power output of 0.8 mW cm−2 and a maximum current density of 6 mA cm−2—far higher than the values for systems based on immobilized enzymes. Enzymatic fuel cells containing a 15% (wt/v) maltodextrin solution have an energy-storage density of 596 Ah kg−1, which is one order of magnitude higher than that of lithium-ion batteries.
Sugar-powered biobatteries could serve as next-generation green power sources, particularly for portable electronics, the researchers suggest in their paper published in Nature Communications.
|“Sugar is a perfect energy storage compound in nature. So it’s only logical that we try to harness this natural power in an environmentally friendly way to produce a battery.”|
In the US alone, billions of toxic batteries are thrown away every year, posing a threat to both the environment and human health, according to the Environmental Protection Agency. Zhang’s development could help keep hundreds of thousands of tons of batteries from ending up in landfills.
While other sugar batteries have been developed, this one has an energy density an order of magnitude higher than others, allowing it to run longer before needing to be refueled, Zhang said.
Zhang and his colleagues constructed a non-natural synthetic enzymatic pathway that strips all charge potentials from the sugar to generate electricity in an enzymatic fuel cell. Then, low-cost biocatalyst enzymes are used as catalyst instead of platinum.
The sugar battery combines maltodextrin, a polysaccharide made from partial hydrolysis of starch with air to generate electricity and water as the main byproducts.
The incomplete oxidation of sugars mediated by one or a few enzymes in enzymatic fuel cells suffers from low energy densities and slow reaction rates. Here we show that nearly 24 electrons per glucose unit of maltodextrin can be produced through a synthetic catabolic pathway that comprises 13 enzymes in an air-breathing enzymatic fuel cell.—Zhu et al.
We are releasing all electron charges stored in the sugar solution slowly step-by-step by using an enzyme cascade.—Dr. Zhang
The fuel sugar solution is neither explosive nor flammable and has a higher energy storage density than hydrogen fuel cells or direct methanol fuel cells. The enzymes and fuels used to build the device are biodegradable.
The battery is refillable; sugar can be added to it much like filling a printer cartridge with ink.
Support for the current research comes from the Department of Biological Systems Engineering at Virginia Tech and Cell-Free Bioinnovations, a biotech start-up, located in Blacksburg, Va. Additional funding was contributed by the National Science Foundation Small Business Innovation Research grant to Cell-Free Bioinnovations Inc.
Zhiguang Zhu, the first author of this paper, and a 2013 biological systems engineering graduate of Virginia Tech, is the principal investigator for the National Science Foundation grant.
Zhiguang Zhu, Tsz Kin Tam, Fangfang Sun, Chun You & Y.-H. Percival Zhang (2014) “A high-energy-density sugar biobattery based on a synthetic enzymatic pathway,” Nature Communications 5, Article number: 3026 doi: 10.1038/ncomms4026