CaltechAUTHORS
Published March 6, 2026 | Version Published
Journal Article Open

Selective cobalt and nickel separation by bioacid-mediated electrowinning

Creators

  • 1. ROR icon Johns Hopkins University
  • 2. ROR icon California Institute of Technology
  • 3. ROR icon Harvard University
  • 4. ROR icon Southern University of Science and Technology

Abstract

The increasing demand for cobalt (Co) and nickel (Ni) in energy storage and industrial applications highlights the need for their efficient separation from both primary mining and nonconventional sources. Electrowinning presents a greener alternative to incumbent solvent extraction but is hindered by the similar reduction potentials of divalent Co and Ni ions. We show that cost-effective and recyclable bioacids can modify ion solvation environments to amplify the reduction potential difference between Co and Ni, with tartaric acid achieving the highest selectivity through formation of a unique dinuclear complex. When applied to ternary lithium-ion battery leachates, the process achieves 99.1% Co purity in batch mode and, in a scalable flow system, stepwise recovery of metallic Co (95.1%), Ni (96.5%), and manganese dioxide (~100%) with high yields. Technoeconomic analysis and life-cycle assessment highlight superior economic and environmental benefits, establishing a sustainable, generalized electrochemical platform for selective Ni/Co separation from complex feedstocks.

Copyright and License

© 2026 the Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).

Acknowledgement

This work was performed, in part, at the Materials Characterization and Processing Center (Whiting School of Engineering) and the Center for Molecular Biophysics, both at Johns Hopkins University.

Funding

We acknowledge financial support to Y.L. from the National Science Foundation (awards 2318122 and 2237096), the David and Lucile Packard Foundation, and the Arnold and Mabel Beckman Foundation.

Contributions

Conceptualization: T.L. and Y.L. Methodology: T.L., C.Z., J.C., Y.M., A.L., Z.L., C.B.M., and P.P. Software: D.-Z.L. and P.P. Formal analysis: T.L., C.Z., H.Z., D.-Z.L., J.C., Y.M., A.L., C.B.M., Z.Q., and P.P. Investigation: T.L., C.Z., J.C., Y.M., J.V.T., A.L., K.N.J., C.B.M., L.Z., A.M., H.D., P.P., and Y.L. Data curation: T.L., D.-Z.L., L.Z., and P.P. Resources: D.-Z.L. and J.V.T. Validation: T.L., C.Z., J.C., P.P., and Y.L. Visualization: C.Z., D.-Z.L., Y.M., J.Z., A.M., and Y.L. Supervision: T.L., C.B.M., P.P., W.A.G., and Y.L. Funding acquisition: W.A.G. and Y.L. Project administration: T.L., W.A.G., and Y.L. Writing—original draft: T.L., C.Z., and D.-Z.L. Writing—review and editing: T.L., C.Z., D.-Z.L., A.M., W.A.G., and Y.L.

Conflict of Interest

T.L. and Y.L. are inventors on a patent application pending submission related to the technologies described here, which is intended to be filed by Johns Hopkins University. The other authors declare that they have no competing interests.

Data Availability

All data and code needed to evaluate and reproduce the results in the paper are present in the paper and/or the Supplementary Materials. This study did not generate new materials. All code used for machine learning–assisted identification of important molecular fragments has been deposited in the database Zenodo (https://doi.org/10.5281/zenodo.17946162) and can also be found on GitHub (https://github.com/Liu-Lab-JHU/Selective-Cobalt-Nickel-Separation).

Supplemental Material

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sciadv.aec7956.pdf

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Additional details

Identifiers

PMCID
PMC12965294
PMID
41790877

Funding

National Science Foundation
2318122
National Science Foundation
2237096
David and Lucile Packard Foundation
Arnold and Mabel Beckman Foundation

Dates

Submitted
2025-10-03
Accepted
2026-01-29

Caltech Custom Metadata

Caltech groups
Division of Chemistry and Chemical Engineering (CCE) , Materials and Process Simulation Center
Publication Status
Published