Sodium-Air Batteries May Best Lithium-Air Batteries

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Lithium-air batteries have the potential to achieve extremely high energy densities that would render the range issue of electric vehicles completely unimportant. However, they still need work, and it’s not a foregone conclusion which battery technology will lead the market in a decade or so. Some researchers have decided to pursue sodium-air batteries instead of lithium-air batteries, and may propel them to the front.

Sodium is an element similar to lithium in that it is highly energetic./reactive. Image Credit: Kompulsa.
Sodium is an element similar to lithium in that it is highly energetic/reactive.
Image Credit: Kompulsa.

Sodium-air batteries can achieve an energy density of 1,600 Wh/kg, which is considerably less than the theoretical maximum energy density of lithium-air batteries (3460Wh/kg) but much higher than lithium-ion batteries (about 200Wh/kg). To put that into perspective. If you replaced your iPhone’s battery with a sodium-air battery, your battery life would be extended by a factor of 8 or 9!

If you replaced the Tesla Roadster’s batteries (116 Wh/kg) with it, the car would be able to travel at least 13 times further per charge, which is 3,172 miles! That could take you across the United States (from California to North Carolina).

Of course, it would be better to just use fewer batteries to achieve a few hundred miles of range, as batteries tend to add tens of thousands of dollars to the cost of electric vehicles.

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Apart from the above points, in practice, sodium-air batteries have achieved a higher energy density than lithium-air batteries — lithium-air batteries just have the potential to achieve a higher energy density (the theoretical maximum mentioned at the beginning of the article).

Sodium-air batteries are also easier to charge, and sodium is cheaper and more abundant than lithium, which may be why GE is using it as well.

Unfortunately, after getting your hopes up, I will have to let you down by telling you that sodium-air batteries can only be recharged 8 times. Researchers are working on this, but there’s clearly a ways to go with this battery technology, too. And progress on this and several other energy storage technologies is coming along. Remember the almost useless lifespan of silicon-based batteries? Even they are being improved.

Follow me on Twitter: @Kompulsa

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Nicholas Brown

Has a keen interest in physics-intensive topics such as electricity generation, refrigeration and air conditioning technology, energy storage, and geography. His website is:

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