On the role of ultrathin lithium metal anodes produced by thermal evaporation

Lithium metal anodes (LMAs) are the preferred option for the next generation of lithium batteries, where high energy density and longer cycle life are required. A new battery design eliminating the LMA in the discharged state provides the highest achievable energy density with reduced safety hazards, though irreversible Li losses impede the practical application of the anode-free concept. In this work, by using an ultrathin layer (<5 μm) of lithium, which is deposited by thermal evaporation on copper current collectors, a reduction on the energy barrier of lithium nucleation during the plating process is demonstrated. Furthermore, the metallic lithium deposited over the charge step provides a homogeneous layer, fairly reducing the dendritic growth and the generation of dead lithium. Finally, a functional solid electrolyte interphase (SEI) with Li 2 O and LiOH as predominant species, gives greater protection to the anode/electrolyte interface, leading to a more stable cycling of the battery. These insights provide a solid starting point for future studies that may lead to practical design changes to improve stability and extend the battery life of lithium metal batteries. • Evaporated Li favors a more homogeneous and denser nucleation of Li in plating. • Native SEI with greater inorganic character is generated with evaporated Li. • Evaporated Li provides a stable cycling of the Li metal anode-less battery.