Apr
5
Lithium Ion Batteries Will Lose Weight
April 5, 2010 | 3 Comments
Yang Shao-Horn, an MIT associate professor of mechanical engineering and materials science and engineering has made significant progress on a technology that could lead to batteries with up to three times the energy density of any battery that currently exists.
Shao-Horn said 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 Air Test Battery from MIT. Click image for more info.
Lithium-air (also known as lithium- oxygen) batteries are similar in principle to the lithium-ion batteries that are now used across the field of portable electronics and are the 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 a flow of air, the batteries themselves can be much lighter. There’s the driver behind so much research with IBM and General Motors as very large examples to have committed major research initiatives on lithium-air technology.
Shao-Horn, along with some of her students and visiting professor Hubert Gasteiger, report in the journal Electrochemical and Solid-State Letters 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. The 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 hopefully, to less expensive alternatives. Using gold and platinum, unless in very small amounts, would be adding in a major build cost.
Lead author doctoral student Yi-Chun Lu explains that the 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.” This is highly encouraging news in its own right. Knowing the physical parameters over many prospects can guide to ever better and more efficient research.
The press release offers two questions with explanations:
Why it matters: 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.
Next Steps: 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; (thus) graphite or some other more stable negative electrode (cathode) materials could be used instead, she says, leading to a safer system.
Lu covers two more points in the press release, “A number of issues must be addressed before lithium-air batteries can become a practical commercial product. 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 confirms the value from the MIT effort calling the research “interesting and important,” and noting the MIT work addresses a significant bottleneck in the development of this technology: the need find an efficient catalyst. Nazri continues that 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.”
In one of the most realistic comments to come from academia, Shao-Horn points out some companies working on lithium-air batteries have said they see it as a 10-year development program. She 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. If it truly demonstrates two to three times the energy density,” of today’s lithium-ion batteries the likely first applications will be in portable electronics such as computers and cell phones that are high-value items and only later would be applied to vehicles once the costs are reduced.
Air batteries, or as the scientific types like to say oxygen batteries, look like the highest potential storage device so far. The driving to lower weights is well worth the effort, yet the water issue and charge recharge cycles are still out there. There’s a ways to go, but getting commercial looks more promising each few months.
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What do cell phones, laptops, mp3 players, power tools and hybrid cars have in common? All these devices are a viable market for lithium-ion (li-ion) batteries, and the demand for these batteries keeps on growing.
While some tout lithium-ion as the next big innovation in electronics, other say they’re rumored to burst into flames and are harder to dispose of. We get down to where the technology is headed and what you need to know as a consumer about li-on batteries.
Do you know? Batteries store energy in the chemicals inside of them. When a device like a flashlight is turned on metal touches the positive and the negative side of the battery, which closes the circuit and the energy is released. There are different types of metals and chemicals that can store energy that are used for batteries. Batteries are made of magnesium dioxide, graphite, electrolytes, zinc oxide and a paper soaked in an electrolyte solution. All of this is sealed in an insulated tube for safety.
Couldnt agree more with that, very attractive article