26th June 2012
Graphene has been used to revive a rechargeable battery technology invented by Thomas Edison (yes, that Thomas Edison) more than 100 years ago in a collision of technologies that could prove very fruitful.
Edison’s idea was that the batteries would power electric vehicles, but the largely technology fell out of use in the 1970s, because although it is very durable, the charge and discharge times are very slow. Those Edison batteries in existence today are mostly used to store surplus energy from wind farms and solar energy arrays.
But researchers at Stanford University, led by chemistry professor Hongjie Dai, have dramatically improved the battery’s performance adding graphene to the mix, resulting in nickel-iron battery that can be fully charged in about two minutes and discharged in less than 30 seconds.
“We have increased the charging and discharging rate by nearly 1,000 times,” said Stanford graduate student Hailiang Wang, lead author of the study. “We’ve made it really fast.”
“In conventional electrodes, people randomly mix iron and nickel materials with conductive carbon,” Wang explains in this press release. “Instead, we grew nanocrystals of iron oxide onto graphene, and nanocrystals of nickel hydroxide onto carbon nanotubes.”
This produced strong bonds between the metal and the carbon nanomaterials, which allow the charges to move quickly between the electrodes and the external circuit.
The only problem is that the improved charge and discharge speeds mean that battery is now more fragile: “It doesn’t have the charge-discharge cycling stability that we would like,” Professor Dai said. “Right now it decays by about 20 percent over 800 cycles. That’s about the same as a lithium-ion battery. But our battery is really fast, so we’d be using it more often. Ideally, we don’t want it to decay at all.”
Dai sees a use for the new Nickel-Iron battery is large scale power storage for the grid; as a boost for lithium-ion batteries in cars, and potentially for the military, where the rapid discharge of power could prove useful.
The results are published in the June 26 issue of the journal Nature Communications.