Facile Electrodeposition Method for Constructing Li2S as Artificial Solid Electrolyte Interphase for High-Performance Li Metal Anode

Abstract

Designing current collectors and constructing efficient artificial solid electrolyte interphase (SEI) layers are promising strategies for achieving dendrite-free Li deposition and practical applications in Li metal batteries (LMBs). Electrodeposition is advantageous for large-scale production and allows the direct formation of current collectors without binders, making them immediately usable as electrodes. In this study, an adherent Cu₂S thin-layer on Cu foil is synthesized through anodic electrodeposition from a Na₂S solution in a one-step process, followed by the generation of Li₂S layers as artificial SEI layers via a conversion reaction (3DLi₂S-Cu foil). The Li₂S layers move from the 3D Cu surface to the deposited Li surface, facilitating uniform and dense Li deposition. The 3DLi₂S-Cu foil structure demonstrates stable cycling performance over 350 cycles in an asymmetric cell, with a capacity of 1 mAh cm^-2 at 1 mA cm^-2. Moreover, symmetric cells with 5 mAh cm^-2 of deposited Li exhibit a stable cycle life for over 1200 h. When paired with commercial LiFePO₄ (LFP), the full cells show substantially enhanced cyclability, regardless of the amount of deposited Li. This study provides new insights into the construction of artificial SEIs for facilitating commercial applications.

Keywords: artificial solid electrolyte interphases; current collectors; dendrite‐free Li deposition; electrodeposition; lithium‐metal batteries.