MIT (Massachusetts Institute of Technology) professors have developed super thin lithium-ion batteries which have been self-assembled by gene-modified viruses that construct their own battery electrodes as they attach to ultra-small nanowires.
Professors Angela Belcher, Paula Hammond and Yet-Ming Chiang, with the help of their team of researchers, wanted to develop high power density batteries into small and lightweight packages as small as a grain of rice.
Batteries hold charge in between the anode and cathode within the electrolyte. Some 3 years ago the researchers genetically-modified a common virus (bacteriophage) reputed to be harmless to humans, that attached itself to molecules of cobalt oxide and gold, with the viruses forming in a regular pattern. The GMO viruses are negatively charged (anode) and are made into layers separated by positively charged (cathode) sheets. The viruses align themselves on the polymer surface when subjected to electrostatic-forces, to form ultrathin wires only 6 nanometers (6 billionths of a meter) in diameter and 880 nanometers in length.
"For the metal oxide we chose cobalt oxide because it has very good specific capacity, which will produce batteries with high energy density," according to Belcher. The energy density is around 2 to 3 times a similar lithium-ion battery and the process takes place at room temperature.
Now, the researchers have done the same thing with the cathode, making the virus bond with iron phosphate and silver, which then attaches themselves to carbon nano-tubes. At present, the battery is about the size of a coin but they believe it can be scaled up or down in size. Another limitation is currently there is only a 100 charge-discharge cycle lifetime but this is also something that can be improved by further genetic modification of the virus.
It is hoped that these battery innovations will soon lead to further weight and cost reductions in battery technology, which in turn, will help make plug-in hybrid electric and electric vehicles better performing, displacing conventional gas-powered vehicles and reducing fossil-fuel use.
Visit: MIT
Show/Hide comment form
