Viruses build tiny batteries

MIT scientists have manipulated the genes in viruses to coax them to build nanowire structures for use in very thin lithium-ion batteries.

The goal of the work, led by MIT Professors Angela Belcher, Paula Hammond and Yet-Ming Chiang, is to create batteries that store as much electrical energy in as small or lightweight a package as possible. The batteries they hope to build could range from the size of a grain of rice up to the size of existing hearing aid batteries.

The MIT team used an intricate assembly process to create the battery anode. They manipulated the genes in a laboratory strain of a common virus, making the microbes collect cobalt oxide and gold. Because these viruses are negatively charged, they can be trapped between oppositely charged polymers to form thin, flexible sheets. The resulting dense, virus-loaded film serves as an anode.

The MIT team then made the cobalt oxide and gold-coated viruses align themselves on the polymer surface to form ultrathin wires. Each virus, and thus the wire, is only 6 nanometres in diameter, and 880 nanometres in length.