As demand for the lithium that powers China’s booming electric car industry continues to grow and shortages loom, scientists are exploring ways to extract the metal from abundant but so far undeveloped sources.
In a paper published by the peer-reviewed journal Nature on December 11, engineers from Nanjing University assessed the potential of innovations that are being developed to extract lithium from “low-quality brines” like seawater and salt lakes.
The metal – a crucial component in EV batteries – is also present in water found in oilfields and in sedimentary deposits but extraction from these sources has not been viable so far.
Do you have questions about the biggest topics and trends from around the world? Get the answers with SCMP Knowledge, our new platform of curated content with explainers, FAQs, analyses and infographics brought to you by our award-winning team.
“Extracting lithium from these sources presents technical challenges owing to low lithium concentrations and high magnesium-to-lithium ratios,” the researchers said in the paper.
While China is the world’s largest refiner of lithium, it is mostly derived from the highly concentrated brine found beneath the salt flats of South America or from hard rock ores which are abundant in countries like Zimbabwe in southern Africa.
To meet domestic demand for the lithium ores, Chinese mining companies have established extraction and processing operations in Zimbabwe.
China dominates global production of lithium-ion batteries, producing 77 per cent of the world’s electric vehicle batteries. Its dominance in the EV sector has prompted tariffs and restrictions in the US and Europe due to fears of overcapacity.
In 2023, combined exports of Chinese lithium batteries – including solar and electric vehicles batteries – topped 1 trillion yuan (US$139 billion).
Despite other emerging technologies like sodium-ion batteries and hydrogen fuel cells, the Chinese researchers said that lithium-ion batteries are expected to continue their dominance for the near future because of their efficiency and energy density.
Rising demand for electric vehicles and renewable energy technologies mean existing supplies of lithium may become insufficient as early as 2029, according to the paper.
“Under current scenarios, the projected demand for the battery sector alone could exhaust 74 to 248 per cent of existing lithium reserves by 2050,” the researchers wrote.
Current methods of obtaining lithium also present challenges, including high energy consumption, greenhouse gas emissions, land disturbance, habitat loss, and depletion of groundwater, they noted.
According to the team’s analysis, while lithium can be recycled effectively it will not be enough to meet future needs, making it crucial to explore new avenues for lithium extraction.
The researchers coined the term “low-quality brine” – defined as holding less than 0.26 grams per litre of lithium, or having a magnesium to lithium ratio higher than 6.15 – for the focus of their study.
At these levels, conventional extraction methods are inefficient because of the lower concentration of lithium as well as the potential for the co-extraction of other elements.
Conventional methods involve evaporating water to concentrate the lithium, before adding in chemicals that will help to extract the metal while leaving behind unwanted ions.
The Chinese team examined the recent progress that has been made in China and internationally as researchers look for ways to work with low quality brines, including by developing pre-concentration methods for easier processing and direct extraction.
One pathway that they studied being explored by a research team from the Chengdu University of Technology is to remove more magnesium and minimise lithium loss through an improved precipitation method.
According to the paper, the Chengdu University team’s crystallisation-precipitation method has shown that it can remove magnesium while limiting lithium loss to just 0.4 per cent.
The Nanjing University researchers also looked into methods based on solvent extraction, which involves mixing the brine with solvents that specifically dissolve lithium, which is then recovered using other solutions.
The research team reported that this approach was deployed at a salt lake in the northwestern province of Qinghai, achieving a lithium extraction efficiency of more than 65 per cent.
Other methods outlined in the study used filtration membranes to physically separate out the lithium using a pressure gradient, as well as differences in concentrations or electrical fields, or electrochemical techniques based on ion properties.
The researchers concluded that a combination of strategies would be “ideal” to optimise lithium extraction, such as using different extraction methods and renewable energy, or combining extraction with processes like seawater desalination.
“We predict that, through persistent research and development efforts in these domains, lithium derived from low-quality brines will emerge as substantial contributors to sustainable lithium production and use,” they wrote.
“This, in turn, will ensure a dependable supply for energy storage systems and facilitate the global shift towards a cleaner and more sustainable energy future.”
More from South China Morning Post:
- China urges schools to teach AI as tech war and ChatGPT drive demand for talent
- Chinese scientists extract lithium from seawater, holding promise for new energy tech
- China’s EV battery industry could grow 7 times bigger in the future, top scientist says
- Hong Kong a launch pad for Chinese EV makers, Xiaomi unveils electric SUV: 7 EV reads
- China’s scientific breakthroughs can lead to linguistic ones too
For the latest news from the South China Morning Post download our mobile app. Copyright 2024.
