Coming soon (hopefully): an ultrafast rechargeable battery that’s also cheap and long-lasting. And since it’s made of aluminum, the new battery is a safer alternative to conventional lithium-ion and alkaline batteries millions of us are using today. The work is described in Nature this week.
For decades, researchers have been eyeing aluminum (the same stuff in foil and beer cans) as material for batteries: It’s cheap, bendy, and has low flammability and high-charge storage capacity. But attempts to develop a commercially viable aluminum-ion battery have been unsuccessful. Like most other batteries, these are comprised of two electrodes: a negatively charged anode (here, made of aluminum) and a positively charged cathode. The challenge has been finding the right material for the cathode -- something capable of producing sufficient voltage after repeated cycles of charging and discharging.
Now, an international team led by Stanford’s Hongjie Dai have accidentally discovered a simple solution using graphite, which is basically carbon. They placed an aluminum anode, graphite cathode, and an ionic liquid electrolyte (a salty liquid, essentially) in a flexible pouch coated with a polymer.
The team hope that their new battery will replace alkaline batteries, which are bad for the environment, and lithium-ion batteries, which can sometimes burst into flames. Even though they’re somewhat of a fire hazard, lithium-ion batteries are used in most of our laptops and smartphones. “Lithium batteries can go off in an unpredictable manner -- in the air, the car or in your pocket,” Dai says in a news release. "Our new battery won't catch fire, even if you drill through it.”
Furthermore, they say their breakthrough battery is also ultra-fast charging and crazy durable. Unlike the hours some of us might spend charging our phones, their prototype has a charge time of one minute. And it’s able to withstand more than 7,500 charge-discharge cycles without losing its capacity. A typical lithium-ion battery, for comparison, lasts about 1,000 cycles.
Unfortunately, this new rechargeable aluminum battery won’t be ready for us any time soon. For one thing, this battery generates about two volts of electricity. While that’s more than your everyday 1.5-volt AA and AAA batteries, as well as any other aluminum prototype thus far, that’s only about half the voltage of a typical lithium battery. “Improving the cathode material could eventually increase the voltage and energy density,” Dai explains. “Otherwise, our battery has everything else you'd dream that a battery should have: inexpensive electrodes, good safety, high-speed charging, flexibility, and long cycle life. I see this as a new battery in its early days.”