Optimal Interfacial Model between the Alloy Surface and Electrolyte Solvation Structure for a Stable Lithium Metal Electrode

Abstract

Long-term mitigation of dendrite growth is the major barrier to building practical Li metal batteries (LMBs). This issue is efficaciously addressed herein, by an advanced alloy surface with optimized interfacial kinetics regulated by the electrolyte solvation structure. By dipping brass skeleton in Ag+-containing solution, the reinforced displacement reaction driven by the large potential gap between Ag+ and Zn can promote the fast formation of a continuous alloy framework with both high lateral and longitudinal Li+ diffusivities for dendrite-free Li deposition. In addition to the displacement-reaction-reinforced alloy surface, this work deciphers exclusively the synergism between the alloy surface and the electrolyte solvation structure, where the strongly coordinated high-concentration electrolyte is revealed as the most suitable model to retain the functionality of the alloy surface. In contrast, both the low-concentration and localized high-concentration electrolytes deteriorate the functionality of the alloy surface by free or diluent-bound solvent molecules, resulting in impeding side products that reduce the active alloying areas. Based on the optimal alloy/solvation structure interfacial model, the high-rate ability and long-cycling performances of the LMBs with a practical capacity of ∼2.5 mAh cm–2 are demonstrated. This strategy is also proved effective for other metal electrodes such as zinc.