Lithium-air battery advance could be jaw-dropping improvement over li-ion
by John Timmer - June 12 2012, 4:38pm EDT
Lithium-air batteries have the potential to be the next big leap in battery tech because they get rid of a lot of the weight and complexity involved with standard batteries. That's because, instead of having all the battery components stored inside the battery itself, lithium-air batteries use oxygen in the atmosphere to bring some electrons to the party. There has been some progress in terms of getting air into the battery and having the oxygen react once it gets there, but the technology still faces a significant challenge: reactive oxygen tends to also react with the battery's components.
The result of these reactions is that existing lithium-air batteries can typically only handle a handful of charge/discharge cycles before they start to decay. But researchers have now found an electrolyte material that doesn't react with oxygen, allowing stable performance over multiple charging cycles. And the theoretical capacity of the battery was staggering, possibly more than ten times that of the lithium-ion tech on the market.
The problem has been, as the researchers put it, that lithium-air batteries have an end-point of lithium peroxide (Li2O2), which forms through an intermediate oxygen radical. That radical is very reactive and will generally decompose the electrolyte that shuttles charged ions around between the battery's two electrodes. If it's not possible to avoid the reactive oxygen, the authors reasoned, the best thing to do is to change the electrolyte to something that doesn't react with oxygen.
Some preliminary research in this area had been done, but the initial materials would only conduct charges well at temperatures above 70°C. The authors came up with a mixture of an ethylene glycol derivative (tetra(ethylene) glycol dimethyl ether) and a complex lithium salt, LiCF3SO3. This worked well at room temperature and, perhaps most significantly, the authors found it went through oxygen reactions so quickly that they couldn't detect any reactive oxygen intermediates. "Equally importantly, the peak corresponding to LiCO3+—one of the most likely products of electrolyte decomposition—is not seen," the authors note.
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http://arstechnica.com/science/2012/06/lithium-air-battery-advance-could-be-jaw-dropping-improvement-over-li-ion/
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I would love to have an all electric car but they don't currently have the range that I need. 