Facile, Atom-Economic, Chemical Thinning Strategy for Ultrathin Lithium Foils

Metallic lithium is considered as the ultimate anode material for lithium-based batteries due to its highest energy density. However, as an anode, commercial Li metal foils are too thick, with a large amount of trouble to balance its exorbitant areal capacity with common cathodes in full cells. Here, a new chemical thinning strategy is proposed via a simple surface dissolving reaction between lithium and naphthalene, which enables scalable, continuous, and roll-to-roll preparation of ultrathin Li foil. A Li foil less than 15 μm with a clean surface can be successfully obtained within 20 min. The thinning rate and thickness of the lithium foil can be easily adjusted by changing the concentration, temperature, and operation mode. The produced Li-Naph solution after thinning can also be used as a multifunctional reagent of great value, and the Li ions in the final waste solution can be further extracted in the form of Li₂CO₃, showing superior lithium atom economy of our strategy.