If you’re not already familiar with lithium-air batteries, you may want to take note. Also known as lithium-oxygen, these batteries are similar to the lithium-ion batteries that now dominate the field of portable electronics. But because lithium-air batteries replace the heavy conventional compounds in such batteries with a carbon-based air electrode and flow of air, the batteries themselves can be much lighter. With the potential of providing energy densities up to three times that of the conventional lithium-ion batteries found in just about every portable consumer electronics device, as well as the incoming wave of electric vehicles, companies from IBM to General Motors are working to develop lithium-air batteries. Most recently, a team of researchers at MIT have made a breakthrough that could help make the commercial development of lightweight rechargeable batteries a reality.
In a paper published this week in the journal Electrochemical and Solid-State Letters, Yang Shao-Horn, an MIT associate professor of mechanical engineering and materials science and engineering, along with some of her students and visiting professor Hubert Gasteiger, reported on a study showing that electrodes with gold or platinum as a catalyst show a much higher level of activity and thus a higher efficiency than simple carbon electrodes in these batteries. In addition, this new work sets the stage for further research that could lead to even better electrode materials, perhaps alloys of gold and platinum or other metals, or metallic oxides, and to less expensive alternatives.
Doctoral student Yi-Chun Lu, lead author of the paper, explains that this team has developed a method for analyzing the activity of different catalysts in the batteries, and now they can build on this research to study a variety of possible materials. “We’ll look at different materials, and look at the trends,” she says. “Such research could allow us to identify the physical parameters that govern the catalyst activity. Ultimately, we will be able to predict the catalyst behaviors.
While some companies working on lithium-air batteries have said they see it as a 10-year development program, Shao-Horn says it is too early to predict how long it may take to reach commercialization. “It’s a very promising area, but there are many science and engineering challenges to be overcome,” she says. “If it truly demonstrates two to three times the energy density” of today’s lithium-ion batteries, she says, the likely first applications will be in portable electronics such as computers and cell phones, which are high-value items, and only later would be applied to vehicles once the costs are reduced.