Tuning ion solvation to bypass facet-selective lithium deposition

Anode-free lithium (Li) batteries maximize energy density by relying on direct Li plating and stripping on metallic substrates, but their practical deployment is limited by uncontrolled and heterogeneous Li deposition. Here, we identify that this heterogeneity is governed by the crystallography of the polycrystalline substrate: high-index facets and grain boundaries direct preferential nucleation, and that the electrolyte solvation structure provides a pathway to bypass this. In the desolvation-limited regime, complete solvent removal must precede charge transfer, leaving bare Li⁺ ions directly exposed to the substrate, and thus strong Li–substrate interactions and facet-selective deposition. Weakly solvating electrolytes preserve partial solvation or anion coordination at the interface, and this solvation shielding attenuates substrate coupling. This decoupling promotes uniform Li plating regardless of crystallographic orientation and grain boundaries. Our findings establish solvation engineering as a viable strategy to suppress crystallographic control in Li metal electrodeposition, and offer design principles for stabilizing Li metal anodes.