Lithium is a finite resource, and the more we use it in batteries, the less is left for other uses. Now, this new method frees up the element from batteries so quickly that it could be a game-changer in terms of material availability.
Demand for lithium-ion batteries that power much of our consumer technology (including electric cars) has skyrocketed over the past decade. The lithium-ion battery market is estimated to be worth $65 billion and is expected to grow by 23% over the next eight years.
Lithium is a relatively light material with the ability to store a lot of energy. Its extraction is quite destructive for the environment and it is also located in areas with geopolitical problems that can threaten supply chains. In addition, there are reports that current lithium mines would not be able to meet the demand that will exist in 2030.
Ideally, we would find ways to recycle lithium stored in used batteries. But that process can be time-consuming, use harsh chemicals and recover very little – less than 5% of the total amount of the element originally used.
Researchers at Rice University came up with a better solution. They started by using chemicals known as deep eutectic solvents — environmentally friendly liquids that can precipitate lithium. “The recovery rate is so low because lithium is typically precipitated last, after all the other metals, so our goal was to focus specifically on lithium,” said Salma Alhashim, one of the study’s lead authors. “Here we used a solvent that mixes choline chloride and ethylene glycol, knowing from our previous work that during leaching in this solvent lithium is surrounded by chloride ions from the choline chloride and leaches into solution.”
Normally, a compound needs to be heated to force the metals to precipitate. For lithium-containing compounds, an oil bath typically provides that heat source. But the process takes quite a while, during which lithium compounds can begin to degrade. To speed things up, the Rice team decided to try microwaves.
The speed increase was impressive. The researchers were able to precipitate lithium almost 100 times faster than with an oil bath. In just 15 minutes recovered 87% of lithiuma process that would take twelve hours using an oil bath.
Using microwave radiation is similar to how a kitchen microwave heats food quickly. Energy is transferred directly to the molecules, causing the reaction to occur faster than with conventional heating methods. The researchers say the method can also be adapted to target other elements by adjusting the composition of the solvent, so it could recover other metals such as cobalt or nickel from batteries.
The team also highlights the ecological benefits of their approach: “This method not only improves the recovery rate but also minimizes the environmental impact, making it a promising step toward implementing large-scale recycling systems for selective metal recovery,” said Pulickel Ajayan, corresponding author of the study and head of the Department of Materials Science and Nanoengineering.
More information: Advanced Functional Materials journal
