The precise separation of critical metals represents one of the greatest technological challenges in the recycling of lithium-ion batteries. Recent research published in the scientific journal Science Advances introduces a greener, highly cost-effective alternative.
By employing biological acids, specifically tartaric acid, researchers have successfully separated nickel and cobalt electrochemically with an outstanding purity of over 99 percent. This method could revolutionize raw material supply for the energy storage and industrial sectors while making the circular economy significantly more sustainable.
The Problem of Similar Reduction Potentials
The growing global demand for cobalt (Co) and nickel (Ni) across both energy storage and other industrial applications makes the efficient extraction of these metals essential, whether from primary mining or non-traditional sources such as spent batteries.
Compared to traditional and widely used solvent extraction methods, electrowinning offers a substantially more environmentally friendly alternative. However, scaling this process industrially has been significantly hindered by a fundamental physicochemical obstacle: the reduction potentials of divalent cobalt and nickel ions are extremely close to each other, making their selective separation from liquids practically difficult.
Tartaric Acid as a Biological Innovation
An international research team (including Tianchen Li, Yayuan Liu, William A. Goddard, Chi Zhang, and colleagues) discovered that cost-effective and recyclable biological acids (bioacids) can modify the solvation environment of these ions. This chemical intervention effectively amplifies the difference between the reduction potentials of cobalt and nickel.
During rigorous laboratory testing, tartaric acid clearly proved to be the most effective additive. Its application achieved the highest selectivity recorded to date. The key to the process’s success lies in tartaric acid’s ability to form a unique dinuclear complex with the metal ions, enabling highly precise, targeted electrochemical separation.
Quantified Results: Over 99 Percent Purity
The technology was tested practically on real leachates derived from ternary (NMC) lithium-ion batteries. The officially published quantitative data demonstrate outstanding conversion efficiency:
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In batch mode, the process achieved a cobalt purity of 99.1 percent.
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In an industrially scalable, continuous flow system, the stepwise recovery of metals yielded metallic cobalt with 95.1 percent purity and nickel with 96.5 percent purity.
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Within this same integrated system, the recovery rate for manganese dioxide approached 100 percent, maintaining an extremely high yield.
Sustainability and Macroeconomic Benefits
The scientific research extended beyond mere laboratory chemistry results. Both a technoeconomic analysis and a life-cycle assessment conducted as part of the study demonstrate that bioacid-mediated electrowinning boasts excellent economic and environmental metrics when compared to existing commercial processes.
This project establishes a sustainable, generalized electrochemical platform that will enable the selective and clean separation of nickel and cobalt even from the most complex feedstocks with high impurity levels. Consequently, it provides a significant, data-backed boost to the global battery recycling industry.
Official Sources and References:
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Original Scientific Publication: Tianchen Li et al., Selective cobalt and nickel separation by bioacid-mediated electrowinning. Science Advances 12 (10), eaec7956 (March 6, 2026). DOI: 10.1126/sciadv.aec7956