The Dependence of Solid Electrolyte Interphase on the Crystal Facet of Current Collector in Li Metal Battery

The continuous electrolyte decomposition and uncontrolled dendrite growth caused by the unstable solid electrolyte interphase (SEI) have largely hindered the development of Li metal batteries. Here, we demonstrate that tuning the facet of current collector can regulate the composition of SEI and the subsequent Li deposition behavior using single‐crystal Cu foils as an ideal platform. The theoretical and experimental studies reveal that the (100) facet of Cu possesses strong adsorption to anions, guiding more anions to participate preferentially in the inner Helmholtz plane and further promoting the formation of the stable inorganic‐rich SEI. Consequently, the single‐crystal Cu foils with a single [100] orientation (s‐Cu(100)) achieve the dendrite‐free Li deposition with enhanced Li plating/stripping reversibility. Moreover, the Li anode deposited on s‐Cu(100) can stabilize the operation of an Ah‐level pouch cell (350 Wh kg−1) with a low negative/positive capacity ratio (~2) and lean electrolyte (2.4 g Ah−1) for 150 cycles. Impressively, this strategy demonstrates universality in a series of electrolytes employed different anions. This work provides new insights into the correlation between the SEI and current collector, opening a universal avenue towards high‐performance Li metal batteries. The effects of Cu facets on the solid electrolyte interphase (SEI) and Li deposition behavior are demonstrated using single‐crystal Cu foils as an ideal platform. The strong adsorption of Cu(100) facet to anions guides more anions to participate in the inner Helmholtz plane and promoting the formation of the stable inorganic‐rich SEI. Consequently, the single‐crystal Cu foil with a single [100] orientation display outstanding performance.