Lithium is a finite resource, and the more we lock up in rechargeable batteries, the less of it we have to use. A new, faster method of releasing the element from such sources could be a game-changer for the material’s availability.
With the way we buy everything rechargeable, including cars, demand for lithium-ion batteries, which power much of our consumer technology, has skyrocketed. The lithium-ion battery market, currently valued at around $65 billion, is expected to grow by 23% over the next eight years.
The value of lithium, a relatively lightweight material with a lot of energy storage capacity, is clear. But mining the element can be environmentally damaging, and geopolitical concerns in many regions where it is abundant can threaten supply chains. We’ve also previously reported that current lithium mines are projected to produce only half of what’s needed to meet demand by 2030.
Taking these factors into account, it is important to find ways to produce lithium-free battery technologies, seek new methods and sources to extract it, or find ways to recycle lithium stored in used batteries. However, recycling lithium can be time-consuming, use harsh chemicals, and result in recovery of less than 5% of the total amount of the element originally used.
Dropping a nuclear bomb
So researchers at Rice University came up with a better solution. They started with chemicals known as deep eutectic solvents (DESs), environmentally friendly liquids that can precipitate lithium and other metals from a solution.
“The recovery rate is very low because lithium usually precipitates last, after all the other metals, so our goal was to figure out how to specifically target lithium,” says Rice PhD graduate Salma Alhashim, one of the study’s lead authors. “Here, we used a DES that is a mixture of choline chloride and ethylene glycol, and we know from previous work that during leaching, lithium is surrounded by chloride ions from the choline chloride and leaks into solution in this DES.”
Normally a compound needs to be heated to cause the metals to precipitate, and in the case of lithium-containing compounds, an oil bath usually provides this heat source. However, the process takes a considerable amount of time, during which time the lithium compounds can begin to decompose.
To speed things up, the Rice team decided to try microwaves, knowing that choline chloride, which helps isolate lithium, is very good at absorbing microwave radiation.
15 minute milestone
The speed increase was impressive. The researchers were able to precipitate lithium nearly 100 times faster than with an oil bath. In fact, it took them just 15 minutes to recover 87% of the lithium—a process that would have taken 12 hours using an oil bath.
“This allowed us to selectively leach lithium over other metals,” said Sohini Bhattacharyya, another lead author and a postdoctoral researcher in the Nanomaterials Laboratory. “Using microwave radiation for this process is similar to how a kitchen microwave rapidly heats food. The energy is transferred directly to the molecules, allowing the reaction to occur much faster than traditional heating methods.”
The researchers say the method could also be adapted to target other elements by adjusting the composition of the DES, making it capable of recovering other metals such as cobalt or nickel from batteries. The team also highlights the environmental benefits of their approach.
“This method not only increases the recovery rate but also minimizes the environmental impact, making it a promising step toward large-scale deployment of DES-based recycling systems for selective metal recovery,” said Pulickel Ajayan, corresponding author of the study and head of the department of materials science and nanoengineering.
The study was published in the journal Advanced Functional Materials.
Source: Rice University