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Home | Green Cars News | Technology | MIT Researchers Working on More Powerful Lithium-Air Battery

MIT Researchers Working on More Powerful Lithium-Air Battery

06 April, 2010 08:47:00

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A team of researchers at MIT has made significant progress on a technology that could lead to lithium-air batteries with up to three times the energy density of any battery that currently exists.

Yang Shao-Horn, an MIT associate professor of mechanical engineering and materials science and engineering, says that many groups have been pursuing work on lithium-air batteries, a technology that has great potential for achieving great gains in energy density. But there has been a lack of understanding of what kinds of electrode materials could promote the electrochemical reactions that take place in these batteries.

Lithium-oxygen (also known as lithium-air) batteries are similar in principle to the lithium-ion batteries that now dominate the field of portable electronics and are a leading contender for electric vehicles. 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. That’s why leading companies, including IBM and General Motors, have committed to major research initiatives on lithium-air technology.

In a paper published this week in the journal Electrochemical and Solid-State Letters, Shao-Horn, 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.

Lightweight batteries that can deliver lots of energy are crucial for a variety of applications — for example, improving the range of electric cars. For that reason, even modest increases in a battery’s energy-density rating — a measure of the amount of energy that can be delivered for a given weight — are important advances.

One issue to be dealt with in developing a battery system that could be widely commercialized is safety. Lithium in metallic form, which is used in lithium-air batteries, is highly reactive in the presence of even minuscule amounts of water. This is not an issue in current lithium-ion batteries because carbon-based materials are used for the negative electrode. Shao-Horn says the same battery principle can be applied without the need to use metallic lithium; graphite or some other more stable negative electrode materials could be used instead, she says, leading to a safer system.

A number of issues must be addressed before lithium-air batteries can become a practical commercial product, she says. The biggest issue is developing a system that keeps its power through a sufficient number of charging and discharging cycles for it to be useful in vehicles or electronic devices.

[source: MIT]

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