The increase in surface area produced by this method can provide "a big advantage," Belcher says, in lithium-air batteries' rate of charging and discharging. But the process also has other potential advantages, she says: Unlike conventional fabrication methods, which involve energy-intensive high temperatures and hazardous chemicals, this process can be carried out at room temperature using a water-based process.
Also, rather than isolated wires, the viruses naturally produce a three-dimensional structure of cross-linked wires, which provides greater stability for an electrode.
A final part of the process is the addition of a small amount of a metal, such as palladium, which greatly increases the electrical conductivity of the nanowires and allows them to catalyze reactions that take place during charging and discharging. Other groups have tried to produce such batteries using pure or highly concentrated metals as the electrodes, but this new process drastically lowers how much of the expensive material is needed.
Altogether, these modifications have the potential to produce a battery that could provide two to three times greater energy density the amount of energy that can be stored for a given weight than today's best lithium-ion batteries, a closely related technology that is today's top contender, the researchers say.
Belcher emphasizes that this is early-stage research, and much more work is needed to produce a lithium-air battery that's viable for commercial production. This work only looked at the production of one component, the cathode; other essential parts, including the electrolyte the ion conductor that lithium ions traverse from one of the battery's electrodes to the other require further research to find reliable, durable materials. Also, while this material was successfully tested through 50 cycles of charging and discharging, for practical use a battery must be capable of withstanding
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology