Implantable Solid Electrolyte Interphase in Lithium-Metal Batteries

Lithium (Li) metal is regarded as the “Holy Grail” electrode because of its low electrochemical potential and high theoretical capacity. Unfortunately, uncontrolled dendritic Li growth induces low coulombic efficiency and poor safety during deposition. Here, we propose an ex situ electrochemical strategy for constructing an ultra-stable implantable solid electrolyte interphase (SEI) on a Li-metal anode. In our study, the SEI rendered dendrite-free Li deposits in a working battery. A Li-metal anode with a stable SEI can be transplanted into ether and ester electrolyte to cycle sulfur (S) and a LiNi_0.5Co_0.2Mn_0.3O₂ (NCM) cathode, respectively. The Li-S cell exhibited superb long-term cycling performance at 1.0 C with an initial capacity of 890 mAh g⁻¹ and capacity retention of 76% after 600 cycles. When matching the NCM cathode, the Li-metal anode with an implantable SEI avoided activation and increased capacity by 50% from 100 to 150 mAh g⁻¹. A Li-metal anode with implantable SEI protection delivers new insights into the rational design of Li-metal batteries with many alternative cathodes and electrolyte systems.