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Lithium-air batteries offer three times the energy density

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April 5, 2010

An experimental lithium-air battery developed at MIT has inlet and outlet on the sides to ...

An experimental lithium-air battery developed at MIT has inlet and outlet on the sides to provide a flow of air, providing oxygen for the battery's operation (Image: Patrick Gillooly/MIT)

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Lithium-air battery technology looks to have a big future. 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 going around (not to mention the incoming wave of electric vehicles), many companies, including IBM and General Motors are pursuing work on lithium-air batteries. Now researchers at MIT have made a breakthrough that could help make the commercial development of lightweight rechargeable batteries a reality.

Lithium-air (also known as lithium-oxygen) batteries are similar in principle to lithium-ion batteries. However, lithium-air batteries electrochemically couple a lithium anode to atmospheric oxygen through a carbon-based air cathode instead of the heavy conventional compounds found in lithium-ion batteries. This means they are able to have higher energy density because of the lighter cathode and the fact that oxygen is freely available in the environment and doesn’t need to be stored in the battery.

Unfortunately lithium-air batteries haven’t become a commercial reality because there has been a lack of understanding of what kinds of electrode materials could promote the electrochemical reactions that take place in these batteries. Now a new study out of MIT reports 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. 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.

Lead author of the paper published this week, doctoral student Yi-Chun Lu, explains that the MIT 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. ”

With more and more portable gadgets finding their way into our daily lives, not to mention automakers turning to rechargeable batteries to power electric cars, the development of lightweight batteries that can deliver lots of energy are seen as an important advance. 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 – offers longer battery life for portable devices and greater range for electric vehicles.

The MIT team admits there are still a number of issues that need to be addressed before lithium-air batteries become a practical commercial product.

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. MIT associate professor of mechanical engineering and materials science, 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.

But 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.

Researchers also need to look into details of the chemistry of the charging and discharging processes, to see what compounds are produced and where, and how they react with other compounds in the system. “We’re at the very beginning” of understanding exactly how these reactions occur, Shao-Horn says.

Gholam-Abbas Nazri, a researcher at the GM Research & Development Center in Michigan, calls this research “interesting and important,” and says this addresses a significant bottleneck in the development of this technology: the need find an efficient catalyst. This work is “in the right direction for further understanding of the role of catalysts,” and it “may significantly contribute to the further understanding and future development of lithium-air systems,” he says.

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.

The MIT team’s research appears in the paper, “The Influence of Catalysts on Discharge and Charge Voltages of Rechargeable Li–Oxygen Batteries,” which is published in the journal Electrochemical and Solid-State Letters.

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
10 Comments

Hitherto the main drawback for Renewables application has been quality batteries at an affordable price. From Lead acid batteries to Nickel cadmium batteries and then Nickel Metal Hydride batteries has been the history of batteries. With more efficient Solar PV Cells made of materials like Gallium Arsenide, Gallium Phosphide , Tandem and organic and lithium-air batteries , Renewable Energy will catch up as decentralised energy in developing countries.

Dr.A.Jagadeesh Nellore(AP),India

Anumakonda Jagadeesh
6th April, 2010 @ 06:19 am PDT

Most portable devices (phones, mp3 players...RC helicopters) use lithium polymer batteries, not lithium ion.

Gruph Norgle
7th April, 2010 @ 01:20 am PDT

Is MIT running behind St Amdrews Universtiy in Scotland? They reported the breakthrough months ago.

David Neilson
8th April, 2010 @ 02:41 pm PDT

@Gruph Norgle, I'm unsure of location variation, However in the EU Lithium ion cells are more common and certainly far easier to get a hold of than Lithium polymer (Li-poly). Not to say you are incorrect, but the better Li-poly batteries are less common due to manufacture costs and limited applications. But you are correct in that you find them in Laptops and electronics where small form factors and energy density outweigh cost considerations. Macs, ipods, RC systems, but not in "most portable devices" The article is accurate in that respect.

@Anumakonda Jagadeesh: Would you please elaborate on "Renewable Energy will catch up as decentralised energy in developing countries" it is not coherent, because if Decentralised is defined

"Decentralization or Decentralisation is the process of dispersing decision-making governance closer to the people and/or citizen. It includes the dispersal of administration or governance in sectors or areas like engineering, management science, political science, political economy, sociology and economics. Decentralization is also possible in the dispersal of population and employment"

In affect you are saying that Renewable Energy will catch up as the dispersal of energy generation in developing countries??? (not coherent) I don't like being pedantic but, renewable energy is at it's forefront in MEDC's. LEDC's have lower values on Human life and quality of life and so choose cheap power generation, like coal fired power stations. If however you mean Energy generation in developing counties is becoming more decentralised due to renewable energy(use of solar cells in remote villages) Then I would agree.

Neon
9th April, 2010 @ 11:31 am PDT

There seems to be some sloppy journalism here. About half-way through your article you attribute a statement to someone called Shao-Horn but hitherto (and indeed subsequently) there is no mention of this person's connection with the story.

Please pull your socks up! This spoils an otherwise interesting article.

...or is it sloppy editing?

Jeff Holden
10th April, 2010 @ 09:30 pm PDT

This article does make a few gross generalized statements that should have been fact checked, but when neophytes read it they will assume they learned something interesting while the rest of us argue over semantics and post comments. This ain't Scientific American people... it's GizMag! Whereas the former caters to those looking for a 4 course meal and hours of pontificating around the dinner table and the latter caters to those just looking for a quick educational snack or the technological equivalent of a candy bar.

As an aside, I agree with Neon regarding the statement "Renewable Energy will catch up as decentralised energy in developing countries" by Dr.A.Jagadeesh Nellore(AP),India

fin

Jonathan Carcopo
14th April, 2010 @ 07:45 am PDT

What the term "decentralized" means in the field of power production is the power is made at the point of consumption, rather than having a huge generating facility with transmission lines taking the electricity to where it is needed. The colloquial term is "off grid". This would be a huge breakthrough for developing countries as it obviates the need for massive infrastructure investments to bring electricity to distant settlements, or widely dispersed rural areas.

Facebook User
11th August, 2010 @ 09:10 am PDT

Lithium Ion and Lithium polymer are the same thing, the full name is Lithium-Ion Polymer Battery. Some companies shorten it or sometimes they even just label it with the acronym

Daniel Pierce
18th May, 2011 @ 12:01 pm PDT

There is one type of lithium battery not yet mentioned, I wonder how long it will be from the time of this posting?

Gargamoth
2nd February, 2012 @ 07:00 pm PST

I just commented on another article and my question was answered here : ) Lithium-air batteries offer three times the energy density. Work past any drawbacks, hopfully with green solutions and I would love to see this in the near future.

Gargamoth
8th May, 2012 @ 08:37 pm PDT
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