Electrochemical ⁶Li isotope enrichment based on selective insertion in 1D tunnel-structured V₂O₅

The renaissance of nuclear energy has generated substantial demand for ⁶Li as a target for nuclear bombardment reactions to produce tritium fuel in breeder reactors. Conventional isotope separation methods utilize differential solubility in mercury amalgams, which pose performance, toxicity, and sustainability concerns. Here, we show that hybrid capacitive deionization wherein Li ions are inserted from aqueous media within the 1D tunnels of a metastable polymorph, ζ-V₂O₅, can be used to selectively sequester ⁶Li ions. An enrichment factor of ca. 57‰ is achieved. X-ray scattering, spectroscopy, and operando spectromicroscopy studies indicate that Li ions are sequestered within 1D tunnels of ζ-V₂O₅ through faradaic processes. ⁶Li and ⁷Li ions are found to migrate at different rates because of subtly different coordination environments. The results illustrate that ζ-V₂O₅ can be utilized as a discriminating host to selectively sequester and enrich ⁶Li from natural abundance precursor flow streams and suggest a distinctive mode of achieving viable isotope separation.