Extracting lithium just got cheaper and more sustainable

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Image: from Rong Xu et al. Continuous lithium extraction from brine by efficient redox-couple electrodialysis. Matter, 2024

New electricity-driven chemical process filters out lithium from brines efficiently and for less than half the cost of current techniques

By Anthropocene Team
August 29, 2024

A new method to extract lithium from salty brines is more efficient and sustainable than current methods. The technology also costs less than half of today’s methods. That could bring down the cost of extracted lithium to less than a quarter of the metal’s current market price, according to a study published in the journal Matter.

Batteries are going to be necessary for electrifying the world’s transportation systems and for storing renewable electricity on the grid. But producing lithium for batteries is a slow, expensive process that takes a huge toll on the environment.

Lithium producers currently mine the metal by evaporating lithium salt-laced brines in giant ponds. This takes a year, requires a lot of land, and generates waste.

Researchers and several companies are now starting to use a technology called direct lithium extraction. These methods use special materials that selectively soak up lithium.

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But there is a new kid on the DLE block based on electrochemical methods. One of those is electrodialysis, which involves transporting ions through a lithium-selective membrane using an applied electric field.

Yi Cui and colleagues at Stanford University have now come up with a new kind of electrodialysis technique. In their reactor, two opposite reactions happen on the two sides of the membrane: hydrogen evolution on one side and hydrogen oxidation on the other.

The reactions result in lithium ions moving through the membrane, creating a higher lithium concentration on the hydrogen evolution side. By connecting several reactor cells in a series, the lithium concentration goes up enough to extract the metal.

The researchers demonstrated continuous lithium extraction from brine for over 100 hours. The method has a lithium selectivity of 100%, and uses only a tenth of the electricity of today’s extraction methods. And, say the researchers, the approach should cost about $3,500 – $4,400 per ton of lithium from brine, while today’s typically costs about US$9,100.

Source: Rong Xu et al. Continuous lithium extraction from brine by efficient redox-couple electrodialysis. Matter, 2024.

Sieving lithium out of salty waters get a boost from a nature-inspired membrane

The innovative new material separates lithium from other metals in salt-lake brines with remarkable efficiency and less waste.
By Anthropocene Team
June 27, 2024

Lithium is key to our electric, low-carbon future. The best known rechargeable batteries for electric vehicles and renewable energy storage rely on the silvery metal. But the supply of lithium is uncertain.

An efficient, sustainable new lithium extraction technology could help combat the lithium shortage. Researchers have designed a membrane that can quickly separate lithium from salt-lake brines. The membrane, reported in the journal Science Advances, draws inspiration from the tiny channels that separate ions in biological tissue.

Conventional lithium mining involves letting lithium salt-laced brines evaporate in giant ponds until the salts can be filtered out. The process takes over a year and produces piles of waste. It will not be sustainable for meeting lithium demand. In 2021, the world used about 100,000 tons of lithium, but that demand will likely go up more than tenfold to over 1.3 million tons by 2030, according to the International Energy Agency.

Many companies are now turning to other more direct ways to get lithium from brines. The technology, called direct lithium extraction, involves chemically or physically filtering out lithium and injecting the salty water back underground. The technologies could be used in low-concentration brines found in many places around the world.

One challenge with DLE technologies is that brines also contain salts of magnesium and that are very similar to lithium salts. Drawing only lithium out is crucial.

And this is what the new membrane does well. The team at the Chinese Academy of Sciences took inspiration from biological channels that are adept at only letting certain ions go through. They made a membrane out of the semiconductor carbon nitride.

The membrane contains a combination of rigid, crystalline forms of carbon nitride as well as soft, non-crystalline forms. This gives the membrane a combination of uniformity and narrow pores. It lets small, smoother lithium ions go through while excluding larger hydrated magnesium ions. The researchers report that the new membrane efficiently extracts lithium ions from a lithium-magnesium mix with a selectivity ratio of 1,708:1. It can operate continuously for 10 days.

Source: Yuanyuan Zhang et al, Congener-welded crystalline carbon nitride membrane for robust and highly selective Li/Mg separation, Science Advances, 2024.

Continuous lithium extraction from brine by efficient redox-couple electrodialysis

https://doi.org/10.1016/j.matt.2024.07.014Get rights and content

Highlights

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    An efficient redox-couple electrodialysis to realize sustainable Li extraction

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    Zero-equilibrium voltage and low overpotential for redox-couple electrodialysis

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    Li extraction with an ultralow voltage, a high efficiency, and a high selectivity

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    A substantially reduced cost compared to conventional Li extraction routes

Progress and potential

Traditional lithium (Li) mining processes are slow, expensive, and environmentally unsustainable. Direct Li extraction (DLE) techniques based on electrodialysis systems have emerged as promising alternatives to conventional approaches, enabling continuous Li extraction from brine and seawater. Here, we introduce a highly efficient redox-couple electrodialysis (RCE) approach to realize sustainable Li extraction from brine with an ultralow operating voltage, a high faradaic efficiency, and a high Li selectivity. Techno-economic analysis reveals that Li extraction via RCE offers a substantially reduced cost compared with traditional Li extraction techniques. The advantages displayed by our RCE approach over conventional Li extraction techniques enhance its feasibility in eco-friendly and cost-effective Li production and could broadly impact the industries of electrified transportation and renewable energy storage.

Summary

The rapid growth of lithium (Li)-ion batteries has catalyzed an unprecedented demand for Li. However, global Li supplies struggle to meet the ever-increasing demand because traditional Li mining processes are slow, expensive, and environmentally unsustainable. Here, we introduce an efficient redox-couple electrodialysis (RCE) approach for sustainable Li extraction from brine. The electrodialysis is driven by the same half-cell electrochemical reaction but operated in opposite directions—hydrogen evolution reaction and hydrogen oxidation reaction—which consumes minimal energy due to the zero-equilibrium full-cell voltage and the low overpotential. We demonstrate continuous Li extraction from brine for over 100 h, with a low operating voltage of 0.25 V, a faradaic efficiency of 88.87%, and a Li selectivity of 0.9954. Notably, the Li extraction via RCE consumes the specific energy of a mere 1.1 kWh kgLi−1, an order of magnitude lower than the energy demands of previously reported Li extraction techniques.

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