Liquid Sodium Batteries: The Ones to Watch

It becomes increasingly obvious that our zero-carbon future depends on cheap reliable batteries. Although it is the theme throughout our chronicles, reliable and cheap seldom go hand in hand. For several decades, researchers believed the key lay in liquid sodium electrolytes. However, scientists at MIT may have cracked the code by using the material as a liquid electrode instead.

How Would a Fluid Work in Liquid Sodium Batteries?

We have had fluid electrodes for a while now in what we call flow batteries. In headline terms, these obtain chemical energy from two components dissolved in liquids contained within the system and separated by a membrane.

However, researchers have been struggling to make these commercially viable for regular use. Work has been ongoing in parallel since 1968 to create a liquid sodium electrolyte instead. Until recently, a suitable separator has stymied researchers, because the ceramic alternatives are expensive and proved too brittle for commercial use.

The Sudden Breakthrough Discovered Quite by Accident

In January 2018, MIT researchers announced they had found a cheap alternative separator in the form of a metal mesh. However, when they opened the cell after testing it, they discovered it had performed the role of an electrode instead.

Science Daily reports a lead researcher saying, “The membrane had performed its role – selectively allowing certain molecules to pass through while blocking others – in an entirely different way. Using its electrical properties rather than the typical mechanical sorting based on the sizes of pores in the material.

“I consider this a breakthrough [in liquid sodium batteries},” researcher Donald Sadoway explains, “for the first time in 50 years, the theoretical advantages of a liquid sodium battery – cheap, abundant materials, safe operation, many charge / discharge cycles without degrading … could translate into a commercially viable product.”

We understand this new technology is ideal for grid-scale battery storage. But just for now, perhaps, too bulky for electric vehicles and laptops. Did we mention, tongue-in-cheek, they used lead compounds for the breakthrough metal grid?