MIT Lithium-Air Battery Achieves New Record Efficiency
A catalyst developed by researchers at MIT makes rechargeable lithium-air batteries significantly more efficient--a step toward making these high-energy-density batteries practical for use in electric vehicles and elsewhere.
The catalyst consists of nanoparticles of a gold and platinum alloy; in testing it was able to return 77 percent of the energy used to charge the battery as electricity when discharged. That's up from the previously published record of about 70 percent, the researchers say. The work, which was reported online this week in the Journal of the American Chemical Society, suggests a new approach to lithium-air battery catalysts that could lead to the even higher efficiencies of 85 to 90 percent needed for commercial batteries.
Lithium-air batteries, which generate electricity by reacting lithium metal and oxygen from the air, are attractive for their potential to store vast amounts of energy. They could be a practical way to store more than three times as much energy, by weight, as today's lithium-ion batteries, extending the range of electric vehicles, for example.
But prototype lithium-air batteries are plagued with problems. In addition to being very inefficient, they typically only last a few dozen charge and discharge cycles. They are also sluggish--only releasing their energy slowly--and prone to contamination by carbon dioxide and water. And the lithium metal used for one of the electrodes is dangerously reactive and eventually grows dendrites, which can lead to short circuits.
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