Tech Insights

Researchers Find More Efficient Lithium Extraction Method for Battery Recycling

April 22, 2024 by Darshil Patel

An improved battery recycling approach directly extracts active lithium from spent batteries at room temperature.

Lithium-ion batteries, or Li-ons, are the dominant battery technology due to their rechargeability, high energy density, and long lifespan. However, there is a growing concern about the end-of-life management of these batteries. Li-ons contain flammable and toxic materials and can harm the environment if not recycled or disposed of properly. Moreover, the mining of lithium can also have environmental consequences. Recycling this valuable material instead of new extraction is critical for sustainability.

 

Discarded lithium-ion batteries.

Discarded lithium-ion batteries. Image used courtesy of Princeton University

 

Due to the batteries' materials, the separation and lithium extraction processes are complex. There aren't enough dedicated recycling facilities to handle the growing volume of spent batteries. Pyrometallurgy and hydrometallurgy are currently the most widely adopted technologies for recycling batteries. Pyrometallurgy involves furnaces breaking down the battery materials and separating lithium as a lithium-containing slag. On the other hand, hydrometallurgy uses chemical leaching to dissolve the battery components in a liquid solution. The purity of lithium achieved in the final stage is usually low.

Researchers at Huazhong University of Science and Technology have proposed a simple and more efficient approach to extracting active lithium from spent batteries. Their solution uses hydrocarbon reagents and ether solvents that bind with lithium and help recover it efficiently.

 

New Lithium Extraction Method for Efficient Battery Recycling

The battery recycling process entails dismantling components, including the anode (containing lithiated graphite) and cathode. Lithium is separated from graphite and other materials using hydrometallurgy or chemical leaching to dissolve unwanted components. Many studies have suggested novel lithium extraction techniques, but their implementation can be challenging. Moreover, they might not be economically feasible compared to other methods for lithium recovery, like leaching lithium from the cathode material.

The Huazhong University researchers’ method is simple and less energy-intensive. The researchers introduce a single-step process using polycyclic aromatic hydrocarbons (PAHs) as lithium-ion carriers and retrieve lithium from lithiated graphite at ambient temperature. They report a lithium extraction efficiency of more than 93% by optimizing extraction reagents, solvents, and process parameters. They tested several reagents with different redox potentials and solubilities and studied their binding mechanisms with lithium. In addition, they also analyzed the reaction between PAHs and solvent combinations and the effects of different leaching processes on lithium recovery.

 

Illustration of the new recycling solution compared to traditional hydrometallurgical methods.

Illustration of the new recycling solution compared to traditional hydrometallurgical methods. Image used courtesy of the authors

 

The researchers tested recovered lithium’s purity by using physicochemical characterization. They observed their recovered active lithium can be employed to prepare high-performance lithium iron phosphate materials comparable to commercial batteries. Upon implementing the lithium iron phosphate cathode fabricated by recovered lithium in 56 Ah prismatic cells, the cells retained around 90% of their capacity after 1200 cycles. The results indicate the approach by Huazhong University researchers has the potential to be economically and practically superior to current recycling techniques.