"We have developed a rechargeable aluminium battery that may replace existing storage devices, such as alkaline batteries, which are bad for the environment, and lithium-ion batteries, which occasionally burst into flames," said Professor Hongjie Dai. "Our new battery won't catch fire, even if you drill through it."
While researchers have tried for a long time to develop a commercially viable aluminium-ion battery, they have not succeeded, mainly because they haven't found suitable materials. "People have tried different kinds of materials for the cathode," Prof Dai said. "We accidentally discovered that a simple solution is to use graphite. In our study, we identified a few types of graphite material that give us very good performance."
For the experimental battery, the Stanford team placed the aluminium anode and graphite cathode, along with an ionic liquid electrolyte, inside a flexible polymer coated pouch.
The team says it has achieved major breakthroughs in aluminium battery performance, including ultra fast charging – the Stanford researchers say their prototype can recharge in a minute.
Meanwhile, while aluminium batteries developed previously did not exceed 100 charge-discharge cycles, the Stanford battery withstood more than 7500 cycles without any loss of capacity.
Currently, the battery generates about 2V. "Our battery produces about half the voltage of a typical lithium battery," Prof Dai said. "But improving the cathode material could eventually increase the voltage and energy density. 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."
