Key to long life, according to a paper in Nature (‘An ultrafast rechargeable aluminium-ion battery‘), is using a three-dimensional graphitic-foam for the cathode.
“People have tried different kinds of materials for the cathode,” said Professor Hongjie Dai. “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.”
The anode is metallic aluminium, with an ionic liquid electrolyte, and the whole thing fits in a flexible polymer-coated pouch, which can be flexed in use.
Terminal voltage is low. “Our battery produces about half the voltage of a typical lithium battery,” said Dai. “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. I see this as a new battery in its early days. It’s quite exciting.”
Personal electronics and grid storage are proposed applications.
“The grid needs a battery with a long cycle life that can rapidly store and release energy,” said Dai. “Our latest unpublished data suggest that an aluminium battery can be recharged tens of thousands of times. It’s hard to imagine building a huge lithium-ion battery for grid storage.”
According to Nature:
- Discharge voltage plateaus near 2V
- Specific capacity of about 70 mAh/g
- Coulombic efficiency of ~98%
- around one minute charge at ~4A/g (~3,000W/kg)
- 7,500 cycles without capacity decay
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via Yuichun
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