For the first time, MIT researchers have shown they can genetically engineer viruses to build both the positively and negatively charged ends of a lithium-ion battery. The new virus-produced batteries have the same energy capacity and power performance as state-of-the-art rechargeable batteries being considered to power plug-in hybrid cars, and they could also be used to power a range of personal electronic devices, said Angela Belcher, the MIT materials scientist who led the research team.