A Golden Age for Lithium-Air EV Batteries?

Charging the Ford Focus EV, one of the current crop of electric vehicles running on Lithium-ion. Credit: Ford

Lithium-ion batteries have become standard for portable electronics because they don?t require a lot of power to run. However, using Li-ion batteries for bigger purposes, like powering an electric car, does not bode as well. Many of the newest electric vehicles can run for only 100 miles (if that) before needing a recharge.

Among the many alternative technologies researchers are investigating is lithium-air, a way to build batteries with a much higher energy density than Li-ion. This week in the journal Science, a group of chemists at the University of St Andrews in Scotland led by Peter Bruce reports on a prototype battery that can more efficiently use oxygen in the atmosphere as a source of power. All it takes is a little gold.

The idea of lithium air is that it could gather the oxygen it requires from the atmosphere, which would allow the battery to be lighter because it wouldn?t need to store heavy metal oxides. The reactions inside the battery would form lithium peroxide while the battery was expending energy, and, in theory, the opposite reaction would happen while the battery was charging, releasing oxygen back out into the air.

But in most prototypes so far, which used carbon-based electrodes, the battery didn?t stand up to repeated discharging and charging cycles, due in part to unwanted reactions happening on the side. That degredation meant the battery wasn?t fully rechargeable. But by making the electrodes out of gold (and adding in some dimethyl sulfoxide), Bruce and colleagues got rid of these side reactions almost entirely. Once all the lithium ions have been used up, all it takes is a flick of a switch to reverse the reaction and make them available once again. Even after 100 charging cycles, the battery retained 95 percent capacity.

Bruce and his colleagues acknowledge that car batteries with electrodes of pure gold don?t make much economic sense. However, he puts forth the idea that it?s possible to take a carbon electrode and thinly coat it in gold to achieve the same results.

Source: http://www.popularmechanics.com/how-to/blog/a-golden-age-for-lithium-air-ev-batteries-10851936?src=rss

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