GoKawiilWhile we make batteries based on many different chemistries, nothing has approached the massive scale at which we can produce lithium batteries. That scale makes the economics of lithium-ion batteries hard to compete with. Even if we develop a superior battery technology, it’s not clear whether we can get manufacturing costs down quickly enough to compete with the efficiency of the lithium supply chain and manufacturing.
The one thing that could change the dynamics is a supply crunch. While lithium is extremely widespread, lithium that can be extracted economically is a different matter. It’s cheapest to extract it from brines, and lithium-rich brines are largely limited to South America. We do obtain some lithium from other sources, but it’s considerably more expensive.
In today’s issue of Science, however, a research team has identified an energy-efficient means of extracting lithium from rocks. The process they’ve designed uses far less energy than existing ones, regenerates all its starting chemicals, and produces byproducts that could also be sold.
Reacting rocks
Like other metals, lithium shows up in a variety of minerals. For example, the US Geological Survey recently took an inventory of all the lithium oxide deposits in the Northeast (they are extensive), which are found in a type of rock called pegmatite. Globally, however, the new paper indicates that the most abundant lithium ore is called spodumene, a lithium-aluminum silicate (LiAl(SiO 3 ) 2 ). And there is some processing of this material going on—it’s just energy-intensive and leaves behind a lot of waste.
That’s because the process starts by heating the mineral to roughly 1,000° C to disrupt its compact structure, after which sulfuric acid is used to leach out the lithium. The resulting lithium sulfate solution is then converted into something useful for battery manufacturing (typically lithium carbonate), leaving behind sulfur-containing waste.
The new work was done by a collaboration between MIT researchers and a couple of Boston-area companies. Their goal was a process that was far more energy-efficient and didn’t produce as much waste. What they came up with is a process where the key chemical used at the start of the process gets re-generated at a later step, and both the silicon and aluminum in the mineral end up in a form that we’re already using in commercial applications.