You know how EVs and practically anything else that runs on lithium batteries aren't really all that 'green' because producing lithium takes a huge toll on the planet?
Scientists at Stanford say they've worked out a way to extract lithium from brine solutions that's far more efficient, cheaper by half, and a lot more eco-friendly than current methods.
That's good news for a bunch of reasons. Thanks to EVs and renewable energy storage systems, in the future we're going to need far more lithium – not less. Lithium extraction firm Lilac Solutions estimates the auto industry alone will require a 20-fold increase in lithium supply.
Next, conventional lithium extraction requires a lot of resources, including energy, land, and water. As things stand, it takes about 500,000 liters of water to extract one ton of lithium.
You also need to mine deep into the earth's crust to get started, and this now-precious resource is concentrated in a handful of places on earth like, Chile and Bolivia. That's a recipe for disaster.
The sad state of lithium extraction
The vast majority of lithium used to produce batteries today comes from mining hard rock in places with salt flats, like the Salar de Atacama salt flats in Chile. You're looking at a lead time of about 18 months to extract lithium from these sources.
That's because you have to first mine and pump mineral-rich brine into evaporation ponds as large as 10 square miles (26 sq km) each. Solar radiation evaporates this brine, which is continually pumped from one pond to another, as its concentration of chemicals increases. It's then collected and sent off to be refined into lithium. Traditional processes typically manage a lithium recovery rate of 40%.
A better way to extract lithium
A research team at Stanford's School of Engineering, led by materials science and engineering professor Yi Cui, has now developed an approach known as “redox-couple electrodialysis,” or RCE.
It works by using electricity to transport lithium from water with a low concentration of the metal to a solution of higher concentration by passing it through a solid-state electrolyte membrane. This is carried out through a series of cells, each of which increases the lithium concentration to a point where it becomes easy to isolate the metal.
How much better is it?
There are numerous advantages to this approach:
- RCE uses only a tenth of the electricity of current extraction methods
- It has a lithium selectivity of almost 100%, which means it's extremely efficient.
- While it typically costs about US$9,100 to extract a ton of lithium from brine, RCE can achieve that for about $3,500 - $4,400.
This method also negates the need for vast evaporation ponds, which could greatly reduce the environmental impact of extracting lithium, as well as expand the number of viable sources for lithium brine around the world.
The brine found in locations across the US, Canada, and Europe can be more challenging to work with: the amount of toxic materials in them, as well as their higher boiling points make them more difficult to process, but this new technique could make those locations economically viable.
The end of our lithium woes?
Other efficient methods for direct lithium extraction (DLE) have been in the works since the 1970s, and some have been commercialized. CNBC notes that 7% of all lithium comes from relatively sustainable DLE methods. Several companies, including Lilac Solutions, EnergyX, Standard Lithium, Sunresin, and China's CATL have been developing and operating DLE methods lately.
The Stanford team's RCE follows close on the heels of another eco-friendly method called adsorbent-based DLE. Here, lithium salts from a mineral-rich brine bind to the surface of a resin, and they can be washed off the adsorbent resin with water. It's said to be more than 90% efficient, and doesn't require expensive acid to enable lithium to bind to an inert material.
The Stanford team’s RCE method, however, seems the most promising of the lot, with its near-100% efficiency, lower electricity requirements, and cheaper operating costs.
What remains to be seen is just how well the RCE process scales up to meet demand, how it can be optimized for fast and safe extraction, and whether it can be applied to seawater that contains lithium salts. Given the projected increase in demand for lithium over the coming years, this clever new technology has the potential to help satiate our increasing appetite for lithium.
The team's research is published in the journal Matter.
Source: Stanford
