Magnetism could hold key to battery recycling

Researchers at Rice University, Texas, have devised a new method to extract purified active materials from lithium-ion battery waste. Their findings, published in the journal Nature Communications, could lead to the effective separation and recycling of valuable battery materials at a minimal fee, contributing to the more sustainable production of electric vehicles (EVs).

“With the surge in battery use, particularly in EVs, the need for developing sustainable recycling methods is pressing,” said James Tour, the T.T. and W.F. Chao Professor of Chemistry and professor of materials science and nanoengineering at Rice University.

Typical recycling techniques involve breaking down battery materials into their elemental forms through thermal or chemical processes. This is energy-intensive and costly, with significant environmental impacts.

The Rice team’s method instead exploits magnetic properties to facilitate the separation and purification of spent battery materials. Their innovation uses a process known as solvent-free flash Joule heating (FJH). This technique, devised by Tour, involves passing a current through a moderately resistive material to rapidly heat and transform it into other substances.

FJH enabled the researchers to heat battery waste to 2500 Kelvin within seconds. During the process, the cobalt-based battery cathodes — typically used in EVs and associated with high financial, environmental and social costs — unexpectedly showed magnetism in the outer spinel cobalt oxide layers, allowing for easy separation from the core. This magnetic separation in turn allowed for efficient purification.

The researchers’ approach resulted in a high battery metal recovery yield of 98% with the value of battery structure maintained.

“Notably, the metal impurities were significantly reduced after separation while preserving the structure and functionality of the materials,” Tour said. “The bulk structure of battery materials remains stable and is ready to be reconstituted into new cathodes.”

Rice graduate students Weiyin Chen and Jinhang Chen as well as postdoctoral researcher and Rice Academy Junior Fellow Yi Cheng were the co-lead authors of the study. The research was supported by the Air Force Office of Scientific Research, U.S. Army Corps of Engineers ERDC and Rice Academy Fellowship.

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