Massachusetts Institute of Technology (MIT) researchers led by professor Angela Belcher have developed batteries by genetically engineering viruses to build the positively and negatively charged ends of a lithium-ion battery. The batteries have the same energy capacity and power performance as the state-of-the-art rechargeable batteries under consideration for use in plug-in hybrid cars, and could be used to power a variety of electronic devices, according to Belcher. The batteries could be manufactured inexpensively and in an environmentally friendly manner. The synthesis of the virus takes place at below room temperature, does not require any harmful organic solvents, and the materials used in the battery are non-toxic. In normal lithium-ion batteries, lithium ions flow between a negatively charged anode, normally graphite, and a positive cathode, normally cobalt oxide or lithium iron phosphate. Previous research by Belcher resulted in viruses capable of building an anode by coating themselves with cobalt oxide and gold, and self-assembling to form a nanowire. The most recent work focused on creating a highly powerful cathode to work with the anode. Building cathodes is more difficult because they must be very conductive to be a fast electrode, but most cathode candidate materials are highly insulating. To solve this problem, MIT researchers genetically engineered viruses that coat themselves with iron phosphate and connect to carbon nanotubes to create a network of highly conductive material. By recognizing the binding to certain materials, specifically carbon nanotubes, the iron phosphate nanowires can be electrically “wired” to conducting carbon nanotube networks. The viruses used are a common bacteriophage, which infect bacteria but are harmless to humans.
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