Ultrasmooth and Dense Lithium Deposition Toward High-Performance Lithium-Metal Batteries.

Abstract

Lithium (Li)-metal batteries (LMBs) with stable solidelectrolyte interphase (SEI) and dendrite-free formation have great potential in next-generation energy storage devices. Here, vertically aligned 3D Cu2 S nanosheet arrays arefabricatedon the surface of commercial Cu foils, which insitu generate ultrathin Cu nanosheet arrays to reduce local current density and Li2 S layers on the surfaces to work as anexcellent artificial SEI. It is found that Li presents a 3D-to-planar deposition model, and Li2 S layers are reversibly movable between the3D nanosheet surface and 2D planar surface of Li during long-term cycling. This enables ultrasmooth and dense Li deposition at 1mA cm-2 , presenting an average thickness of ≈53.0µm at 10 mAh cm-2 , which is close to the theoretical Li foil thickness and is highly reversible at different cycles. Thus, 1150 stable cycles with high Coulombic efficiency (CE, 99.1%) at ether-based electrolytes and 300 stable cycles with high CE (98.8%) at carbonate electrolytes are realized in half-cell with a capacity of 1 mAh cm-2 at 1mAcm-2 . When coupled with commercial cathodes (LiFePO4 or LiNi0.8 Co0.1 Mn0.1 O2 ), the full cells present substantially enhanced cyclability under high cathode loading, limited (or zero) Li excess, and lean electrolyte conditions, even at -20 °C.