Advanced PEO/SN/LLZTO artificial solid electrolyte interphase for long-cycling lithium metal batteries

Lithium metal batteries have been widely used in energy storage applications owing to their high theoretical energy density. However, the unstable solid electrolyte interphase (SEI) in the batteries lead to the formation of lithium dendrites and “dead lithium”, thus affecting the safety and cycle life of the battery. To address this issue, an artificial SEI was prepared using a polymer coating strategy. The introduction of succinonitrile (SN) accelerates ion transport by promoting the dissociation of lithium salts. The solid electrolyte Li_6.5La₃Zr_1.5Ta_0.5O₁₂ (LLZTO) enhances the mechanical strength of artificial SEIs and promotes ion conduction. Furthermore, the competitive coordination between LLZTO and SN inhibits lithium anode corrosion, forming an SEI rich in LiF and Li₃N. Therefore, the lithium metal anode modified with an artificial SEI can be stably plated/stripped for more than 10000 h. The LiFePO₄ full cell assembled with the modified anode exhibited a discharge specific capacity of 133 mAh·g⁻¹ and a capacity retention of 97% after 1000 cycles at 2 C (1 C = 170 mA·g⁻¹). Notably, the anode modified with the artificial SEI exhibited excellent electrochemical performance even at low temperatures.