High Li+ coordinated solvation sheaths enable high-quality Li metal anode

An advance Li-sphere possessing a definitely regular morphology in Li deposition enables a well-defined more robust structure and superior solid-electrolyte interphase (SEI) to achieve high-efficiency long-term cycles in Li metal anode. Here, a new sight of high Li+ cluster-like solvation sheaths coordinated in a localized high-concentration NO3-(LH-LiNO3) electrolyte fully clarifies for depositing advanced Li spheres. Moreover, we elucidate a critical amorphous-crystalline phase transition in the nanostructure evolution of Li-sphere deposits during the nucleation and growth. Li-sphere anode exhibits ultra-stable structural engineering for suppressing Li dendrite growths and rendering ultralong life of 4000 cycles in symmetrical cells at 2 mA cm(-2). The as-constructed Li spheres/3DCM|LiFePO4 (LFP) full cell delivers a high capacity retention of 90.5% at 1 C after 1000 cycles, and a robust dendrite-free structure also stably exists in Li-sphere anode. Combined with high-loading LFP cathodes (6.6 and 10.9 mg cm(-2)), superb capacity retentions are up to 96.5% and 92.5% after 800 cycles at 1 C, respectively. Cluster-like solvation sheaths with high Li+ coordination exert significant influence on depositing a high-quality Li-sphere anode.

Automated summary

An advanced Li-sphere with a regular morphology is able to achieve high-efficiency long-term cycles in Li metal anode due to its well-defined structure and superior solid-electrolyte interphase (SEI). The presence of high Li+ cluster-like solvation sheaths in a high-concentration NO3-(LH-LiNO3) electrolyte explains the deposition of advanced Li spheres. The structural evolution of Li-sphere deposits during nucleation and growth involves a critical amorphous-crystalline phase transition. The Li-sphere anode exhibits stable structural engineering, suppressing Li dendrite growth and demonstrating a long life of 4000 cycles in symmetrical cells at 2 mA cm(-2). In addition, the Li-sphere anode also exhibits a robust dendrite-free structure, achieving a high capacity retention of 90.5% after 1000 cycles in combination with a LiFePO4 (LFP) cathode.