Virus Power

THE NEXT GENERATION of batteries could be made with the help of an unusual manufacturing partner—a virus that infects bacteria. Using an environmentally benign process, scientists at Massachusetts Institute of Technology and Korea Advanced Institute of Science & Technology coaxed a genetically engineered virus into building and wiring the cathode of a lithium-ion battery (Science, DOI: 10.1126/science.1171541).

MIT materials science professor Angela M. Belcher, who spearheaded the work, previously used genetically engineered viruses to fabricate the anode portion of a battery. Working with cathode materials, she says, proved to be more difficult because the material needs to be good at conducting both electrons and ions and also has to work well at high voltages. By tweaking one gene in the M13 virus, Belcher's team was able to get it to build itself a coat of amorphous iron phosphate, a promising material for lithium-ion batteries that's been hampered by low electronic conductivity.

To boost the system's conductivity, the team manipulated another gene in the virus so that it would latch onto a single-walled carbon nanotube. The nanotube acts as viral wiring, connecting the cathode to the battery's other components. The tighter the virus grabs the nanotube, the better the battery performs, the researchers found.

"This is a creative approach to producing heterostructures at the nanoscale in order to address one of the most significant problems in lithium-ion batteries," comments Paul S. Weiss, a chemistry and physics professor at Pennsylvania State University.

The battery fabrication process is also quite mild, Belcher adds. It takes place below room temperature and requires neither harmful organic solvents nor toxic starting materials. "We can't use anything that's harmful to our organisms," she explains.

The team prepared a prototype battery using the viral components, but Belcher tells C&EN that she'd like to find better performing materials before scaling up the process to make these batteries commercially. What the work shows "is that we can use benchtop conditions to make batteries that are as good as what's out there," she says. "What we're focused on now is doing better than that."