The Lithium-6 Bottleneck — Can the West Build a Fusion-Fuel Supply Chain in Time?

Every deuterium-tritium fusion plant breeds its tritium in a lithium blanket, and that blanket runs not on natural lithium but on lithium enriched to ~30–90% in the ⁶Li isotope. The uncomfortable fact this report documents: the West has essentially no ⁶Li enrichment capacity. The only legacy process, COLEX, uses tonnes of liquid mercury and is effectively barred under the Minamata Convention; the United States shut its lithium-enrichment line at Y-12 decades ago; and today only Russia and China are believed to enrich ⁶Li at any scale, selling small quantities at roughly $50,000/kg. Against that, a GW-scale D-T plant needs on the order of 50–100 t of ⁶Li, and the literature projects >100 t of demand within about a decade as DEMO-class machines begin construction. The question is whether a supply chain can be stood up in time, and by whom. The finding: three routes are now in a real race — a mercury-free electrochemical method (Texas A&M/ETH, 2025), a solvent-exchange process (Molten Salt Solutions, which signed the first commercial enriched-lithium supply agreements with Type One Energy and Gauss Fusion in March 2026), and revived atomic-vapor laser separation (Hexium, with an April 2026 DOE-funded CRADA at Lawrence Livermore) — each targeting kilogram-scale deliveries in 2027 and commercial output around 2029. Our base case: the binding metric is separative capacity (SWU/yr), not lithium supply; because natural lithium is abundant and cheap, the entire value and scarcity sit in isotope separation. Listed exposure is thin and indirect — the pure-plays are private — which is itself the signal.