Researchers have developed a new method to successfully extract purified active materials from battery waste. The method will help to properly separate and recycle battery materials at a low cost.
The method will also contribute to the greener production of electric vehicles and tackle the environmental issue of efficiently recycling lithium-ion batteries.
The research team at Rice University led by James Tour, the T.T. and W.F. Chao Professor of Chemistry and professor of materials science and nanoengineering proposed that magnetic properties could facilitate the separation and purification of spent battery materials.
Sustainable recycling method
“With the surge in battery use, particularly in EVs, the need for developing sustainable recycling methods is pressing,” Tour said.
Battery recycling techniques used to involve breaking down the energy storage devices into their elemental forms through energy-intensive thermal or chemical processes that were expensive and have a concerning environmental impacts.
In this study, researchers used the solvent-free flash Joule heating (FJH) method, which involves passing a current through a moderately resistive material to rapidly heat and transform it into other substances.
High battery metal recovery
Using FJH, the researchers heated battery waste to 2,500 Kelvin within seconds, creating unique features with magnetic shells and stable core structures. The magnetic separation allowed for efficient purification, according to RICE researchers.
Their method resulted in a high battery metal recovery yield of 98%, with the value of battery structure maintained.
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.
Metal impurities were significantly reduced
“Notably, the metal impurities were significantly reduced after separation while preserving the structure and functionality of the materials,” said Tour. “The bulk structure of battery materials remains stable and is ready to be reconstituted into new cathodes.”
The research published in the journal Nature Communication presented the method combined with magnetic separation to restore fresh cathodes from waste cathodes, followed by solid-state relithiation. The entire process is called flash recycling.
Cathodes reveal intact core structures
After FJH, the cathodes reveal intact core structures with hierarchical features, implying the feasibility of their reconstituting into new cathodes. Relithiated cathodes are further used in LIBs, and show good electrochemical performance, comparable to new commercial counterparts.
The study highlights that flash recycling offers greater environmental and economic benefits compared to traditional destructive recycling processes.
The study maintains that the FJH process can presumably be integrated into a similar continuous system for spent LIB recycling.
In addition, recent works have demonstrated that the same FJH process and carbothermal shock method can be used to achieve the effective regeneration of the graphite anode from spent graphite, indicating that flash recycling method can simultaneously solve both cathode and anode recycling problems arising from spent battery accumulation.
Since the FJH process is being industrially scaled to 1 ton per day per facility, manufacturability is attainable while minimizing dependence on freshly mined metal ores to produce LIBs, according to the study.
