New strategy for a safe, rechargeable sodium battery

I just ran across this paper “Alternative strategy for a safe rechargeable battery” in Energy Environ. Sci.. Like all new technologies, it may prove to have more problems than is apparent at first. That being said, this technology looks remarkable. It’s a battery chemistry that can use lithium or sodium metal. That is inherently a more energetic battery than a lithium-ion.

A lithium metal battery is likely to hold about 2-3 times more energy than a lithium-ion battery (all else being equal). So that alone will make battery operated cars competitive with gasoline. A sodium metal battery will be a little worse than a lithium metal battery, but better than a lithium-ion. But in terms of price, a sodium-based battery will win by a large margin.

Lithium is in short supply. A global transportation system based on lithium chemistry will take a huge amount of lithium. It will take big new discoveries to meet global demand if every car and truck is electrified. That is not the case for sodium. There’s lots of sodium.

So, if we want to transition to solar-storage for the grid, and battery-electric for transportation, it means we need a battery chemistry just like this: sodium, separator, carbon.

2017-03-06 09_31_12-Krita

The key was the separator. Everything else seems cheap and relatively easy. The trouble is that most separators allow the sodium to form dendrites. Those dendrites act like little spears that punch through the separator itself. Once that happens, you get a short circuit and a fire. The U of Texas researchers made a sodium glass separator that prevents this. Here’s hoping this is the first the step to $0.10 per Wh capacity.