A new battery chemistry could improve the efficiency and longevity of lithium-air batteries in a way that is “very scalable, cheap and much safer” than its predecessors, according to a paper published this week in Nature Energy.
Lithium-air batteries have the potential to deliver a high energy output relative to weight. But, previous designs have faced significant challenges including high energy losses, quick degradation, and expensive components that make them incompatible with conventional sealed batteries.
According to MIT Professor Ju Li and his co-authors in their new paper, their new nanolithia cathode battery design can overcome all of these challenges.
The key of this new battery is its ability to overcome the 1.2-volt mismatch between input and output voltages in today’s lithium-air batteries. All told these previous designs waste about 30% of electricity in the charging process as heat, which “can actually burn if you charge it too fast” says Professor Li.
In their new battery, Li and his team have reduced this mismatch to 0.24 volts, meaning that only 8% of the electricity is lost as heat. This reduction means higher efficiency, while also addressing many of the safety concerns related to high levels of heat dissipation (i.e. fires).
The reduction in the voltage mismatch is made possible by nanoparticles called “nanolithia”. These small particles contain both lithium and oxygen – a highly unstable combination on its own, but one that is stabilized when embedded within a cobalt oxide matrix as Li and his team have done.
This nanolithia-embedded matrix allows for oxygen to be kept in solid form throughout the charge/discharge process. This is a significant change from conventional lithium-air batteries, where oxygen is taken from the outside air and is allowed to revert back to a gas.
Li and his team – which includes research scientists Akihiro Kushima and Zongyou Yin of MIT, Lu Qi of Peking University, and Khalil Amine and Jun Lu of Argonne National Laboratory - have already completed successful lab tests of this technology and expect to develop a practical prototype within a year.