"We can make them in larger diameters," Belcher said, "but they are all 880 nanometers in length," which matches the length of the individual virus particles. And, "once we've altered the genes of the virus to grow the electrode material, we can easily clone millions of identical copies of the virus to use in assembling our batteries.
"For the metal oxide we chose cobalt oxide because it has very good specific capacity, which will produce batteries with high energy density," meaning it can store two or three times more energy for its size and weight compared to previously used battery electrode materials. And adding the gold further increased the wires' energy density, she added.
Equally important, the reactions needed to create nanowires occur at normal room temperatures and pressures, so there is no need for expensive pressure-cooking technology to get the job done.
The work is important, too, because energy density is a vital quality in batteries. A lack of energy density - meaning the amount of charge a battery of a given size can usefully carry - is what has hampered development of electric cars, since existing batteries are generally too heavy and too weak to compete with gasoline as an energy source. Still, battery technology is gradually being improved and may someday even become competitive as the price of oil escalates.
"The nanoscale materials we've made supply two to three times the electrical energy for their mass or volume, compared to previous materials," the team reported.
The researchers' work was spurred by "growing evidence that 'nanostructured' materials can improve the electrochemical properties of lithium-ion batteries," compared to more conventional batteries based on older technologies, the team wrote in Science.
But to create new battery materials, Belcher noted, special
Source:Massachusetts Institute of Technology