A new inexpensive aluminium battery that could charge cellphones in just one minute has been developed by Stanford scientists.
The new aluminium battery is much safer than existing lithium-ion and alkaline batteries in wide use today and does not catch fire, researchers said.
"We have developed a rechargeable aluminium battery thatmay replace existing storage devices, such as alkaline batteries, which are bad for the environment, and lithium-ion batteries, which occasionally burst into flames," said Hongjie Dai, a professor of chemistry at Stanford University.
"Our new battery won't catch fire, even if you drill through it," said Dai.
Aluminium has long been an attractive material for batteries, mainly because of its low cost, low flammability and high-charge storage capacity, researchers said.
An aluminium-ion battery consists of two electrodes: a negatively charged anode made of aluminium and a positively charged cathode.
"People have tried different kinds of materials for the cathode," Dai said.
"We accidentally discovered that a simple solution is to use graphite, which is basically carbon. In our study, we identified a few types of graphite material that give us very good performance," said Dai.
The team placed the aluminium anode and graphite cathode, along with an ionic liquid electrolyte, inside a flexible polymer-coated pouch.
"The electrolyte is basically a salt that's liquid at room temperature, so it's very safe," said Stanford graduate student Ming Gong, co-lead author of the study.
Aluminium batteries are safer than conventional lithium-ion batteries used in millions of laptops and cell phones today, Dai added.
Smartphone owners know that it can take hours to charge a lithium-ion battery. But the team reported "unprecedented charging times" of down to one minute with the aluminium prototype.
Aluminium batteries developed at other laboratories usually died after just 100 charge-discharge cycles. But the Stanford battery was able to withstand more than 7,500 cycles without any loss of capacity.
"This was the first time an ultra-fast aluminium-ion battery was constructed with stability over thousands of cycles," researchers said.
"Another feature of the aluminium battery is flexibility. You can bend it and fold it, so it has the potential for use in flexible electronic devices. Aluminium is also a cheaper metal than lithium," Gong said.
The study was published in the the journal Nature.
