Xiao Su in his laboratory at the University of Illinois at Urbana-Champaign. Photo: Fred Zwicky.
Xiao Su in his laboratory at the University of Illinois at Urbana-Champaign. Photo: Fred Zwicky.

Spent lithium-ion batteries contain valuable metals that are difficult to separate from each other for recycling purposes. Used batteries present a sustainable source of these metals, especially cobalt and nickel, but current methods used for their separation have environmental and efficiency drawbacks. Now, a new technology developed by researchers at the University of Illinois at Urbana-Champaign uses electrochemistry to efficiently separate and recover the metals, making spent batteries a highly sustainable secondary source of cobalt and nickel – the reserves of which are currently dwindling.

Led by chemical and biomolecular engineering professor Xiao Su, the researchers used selective electrodeposition to recover valuable metals from commercially sourced lithium nickel manganese cobalt oxide – or NMC – battery electrodes. This method, reported in a paper in Nature Communications, produces final product purities of approximately 96.4% for cobalt and 94.1% for nickel from spent NMC electrode wastes.

According to Su, cobalt and nickel have similar electrochemical properties – or standard reduction potentials – making it challenging for chemists to recover pure forms of each metal from battery electrodes.

“There are a variety of methods available for the recovery of cobalt and nickel from battery electrodes, but they have drawbacks,” Su said. “Most require energy-intensive high-temperature processes or strong solvents that present disposal challenges. The industry demands methods that will not cause additional problems like high energy consumption or toxic waste.”

The unique aspect of this study is the team’s development of a tunable liquid electrolyte and a polymer coating on the electrodes.

In the lab, the researchers combined the electrolyte-polymer method with dismantled, leached and liquefied components of fully discharged NMC battery electrodes. By adjusting the salt concentrations of the electrolyte and the thickness of the polymer coating, the researchers found that distinct deposits of cobalt and nickel accumulated on the electrode surfaces through sequential electrodeposition. By the end of the process, the electrode had collected high-purity coatings of cobalt and nickel.

An economic analysis of this new approach showed that it was competitive with current lithium-ion battery recycling methods once material revenue, material cost and energy consumption were all considered.

“There’s further engineering optimization of the process that will be needed going forward, but this first proof-of-concept study confirms that low-temperature cobalt and nickel electrochemical recovery is possible,” Su said. “We’re very excited because the study shows a great example of sustainable electrically driven separations being used to recycle electrochemical batteries.”

This story is adapted from material from the University of Illinois at Urbana-Champaign, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.