A century-old battery originally developed by Thomas Edison to power cars may find new life today with new electrodes developed at Stanford University that allow the battery to be charged and discharged much more rapidly than older versions of the device. The Edison battery, which uses nickel and iron electrodes immersed in an alkaline medium, uses cheap metals that are readily available. Unlike modern lithium-ion batteries, moreover, the Edison battery is unlikely to explode in a crash. But because it takes so long to be charged and releases its power relatively slowly, it has been displaced by lead-acid batteries in conventional automobiles and by lithium-ion batteries in electric cars and most other applications that require regular re-charging.
A team headed by chemist Hongjie Dai of Stanford’s Precourt Institute for Energy noted that carbon has been used frequently to enhance electrical conductivity in electrodes and decided to try it in an Edison battery. He and his colleagues grew nanocrystals of iron oxide on sheets of graphene (sheets of carbon only one atom thick) for one electrode and nanocrystals of nickel hydroxide on multi-walled carbon nanotubes, each consisting of about 10 concentric graphene sheets rolled together.
The team reported Wednesday in the journal Nature Communications that they made a one-volt prototype battery with just enough power to operate a flashlight. The battery can be fully charged in 2 minutes and discharged in 30 seconds, about 1,000 times faster than a conventional Edison battery. They say that the technology can be readily scaled up to produce larger batteries.
The larger batteries probably could not be used to power a car because their energy density is not high enough, Dai said. “But it could assist lithium-ion batteries by giving them a real power boost for faster acceleration and regenerative braking.” They could also find applications in the military and for emergencies in which rapid charging is necessary.
The primary problem with the battery at present is that it loses about 20% of its capacity over 800 discharging-charging cycles. “That’s about the same as a lithium-ion battery,” Dai said. “But our battery is really fast, so we’d be using it more often. Ideally, we don’t want it to decay at all.”
Concluded Dai: “I think Thomas Edison would be really happy to see this progress.”