Alternative Energy

A team of researchers at the Massachusetts Institute of Technology (MIT) is working on lithium-air batteries that could help in generating more powerful, lightweight batteries than available currently. Yang Shao-Horn is an MIT associate professor of mechanical engineering. According to him many research groups are trying to improve on lithium-air batteries. But they have difference of opinions about the types of electrode materials to be used. It has to be noted that electrode materials are responsible for electrochemical reactions happening inside these batteries.

Lithium-air batteries, also known as the lithium-oxygen batteries, work on the same principle as the lithium-ion batteries. Presently lithium-ion batteries are flooding the market and being used in the portable electronics and are a leading contender for electric vehicles. Lithium-air batteries possess a big advantage over conventional batteries. Their main components don’t have the heavy conventional compounds. They have a carbon-based air electrode and with flow of air these air-batteries are quite light hence can be utilized in electronics that themselves can be much lighter. Lithium-air batteries offer three times the energy density than the conventional batteries. They can be easily utilized in electronic devices and hybrid cars. Renowned companies like IBM and General Motors are sensing the potential lithium-air batteries hold that is why they are investing in major research projects on lithium-air technology.

How do lithium-air batteries work? Lithium-air batteries electrochemically couple a lithium anode to oxygen derived from atmosphere. Their biggest advantage is their cathode is a carbon-based air cathode instead of the heavy conventional compounds found in lithium-ion batteries. This culminates in higher energy density because cathode is lighter and oxygen is available in surroundings.

Yang, along with some of the students and visiting professor Hubert Gasteiger are catching up with those electrodes that have gold and platinum working as catalysts. Gold or platinum electrodes exhibit a higher level of activity that naturally leads to higher efficiency. This work may open wider avenues for experimenting with other metals or metallic oxides that are cheaper than gold and platinum.

If we study the chemical properties of lithium we can learn that in metallic form, lithium is highly reactive in the presence of even a tiny fraction of water. But this will not cause any safety issue because in current lithium-ion batteries, carbon-based materials are used for the negative electrode. Shao-Horn explains that the same battery principle can be applied without using metallic lithium. They can choose graphite or some other more stable negative electrode materials leading to a safer system.

Doctoral student Yi-Chun Lu who is lead author of the paper, elaborates further. She explains that this team has devised a technique for analysing the activity of different catalysts in the batteries. They can look into a variety of possible materials as catalysts. 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 behaviours.” Now researchers at MIT have made a breakthrough that would help the commercial development of lightweight rechargeable batteries.

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