Ultra-Smooth and Dense Lithium Deposition Toward High-Performance Lithium Metal Batteries.

Lithium (Li) metal batteries (LMBs) with stable solid-electrolyte interphase (SEI) and dendrite-free formation have great potential in next-generation energy storage devices. Here, we fabricate three-dimensional (3D) vertically aligned Cu 2 S nanosheet arrays on surface of commercial Cu foils, which in-situ generate ultrathin Cu nanosheet arrays to reduce local current density and Li 2 S interfacial layers on the surfaces to work as excellent artificial SEI. It is found that Li presents a 3D to planar deposition model and Li 2 S layers are reversibly movable between 3D nanosheet surface and 2D planar surface of Li during long-term cycling. This enables ultra-smooth and dense Li deposition at 1 mA cm -2 , presenting an average thickness of ∼53.0 μm 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 (99.1%) at ether-based electrolytes and 300 stable cycles with high Coulombic efficiency (98.8%) at carbonate electrolytes are realized in half-cell with a capacity of 1 mAh cm -2 at 1 mA cm -2 . When coupled with commercial cathodes (LiFePO 4 or NCM811), the full-cells present substantially enhanced cyclability under high cathode loading, limited (or zero) Li excess, and lean electrolyte conditions, even at -20°C. This article is protected by copyright. All rights reserved.