High-Purity Lithium Metal Films from Aqueous Mineral Solutions

[Image: see text] Lithium metal is a leading candidate for next-generation electrochemical energy storage and therefore a key material for the future sustainable energy economy. Lithium has a high specific energy, low toxicity, and relatively favorable abundance. The majority of lithium production originates from salt lakes and is based on long (>12 months) periods of evaporation to concentrate the lithium salt, followed by molten electrolysis. Purity requires separation from base metals (Na, K, Ca, Mg, etc.), which is a time-consuming, energy-intensive process, with little control over the microstructure. Here, we show how a membrane-mediated electrolytic cell can be used to produce lithium thin films (5–30 μm) on copper substrates at room temperature. Purity with respect to base metals content is extremely high. The cell design allows an aqueous solution to be a continuous feedstock, advocating a quick, low-energy-consumption, one-step-to-product process. The film morphology is controlled by varying the current densities in a narrow window (1–10 mA/cm(2)), to produce uniform nanorods, spheres, and cubes, with significant influence over the physical and electrochemical properties.