In-situ constructed polymer/alloy composite with high ionic conductivity as an artificial solid electrolyte interphase to stabilize lithium metal anode

Lithium (Li) metal is regarded as the best anode material for lithium metal batteries (LMBs) due to its high theoretical specific capacity and low redox potential. However, the notorious dendrites growth and extreme instability of the solid electrolyte interphase (SEI) layers have severely retarded the commercialization process of LMBs. Herein, a double-layered polymer/alloy composite artificial SEI composed of a robust poly(1,3-dioxolane) (PDOL) protective layer, Sn and LiCl nanoparticles, denoted as PDOL@Sn-LiCl, is fabricated by the combination of in-situ substitution and polymerization processes on the surface of Li metal anode. The lithiophilic Sn-LiCl multiphase can supply plenty of Li-ion transport channels, contributing to the homogeneous nucleation and dense accumulation of Li metal. The mechanically tough PDOL layer can maintain the stability and compact structure of the inorganic layer in the long-term cycling, and suppress the volume fluctuation and dendrites formation of the Li metal anode. As a result, the symmetrical cell under the double-layered artificial SEI protection shows excellent cycling stability of 300 h at 5.0 mA·cm⁻² for 1 mAh·cm⁻². Notably, the Li||LiFePO₄ full cell also exhibits enhanced capacity retention of 150.1 mAh·g⁻¹ after 600 cycles at 1.0 C. Additionally, the protected Li foil can effectively resist the air and water corrosion, signifying the safe operation of Li metal in practical applications. This present finding proposed a different tactic to achieve safe and dendrite-free Li metal anodes with excellent cycling stability.