LiI-Coated Li-Sn Alloy Composite Anode for Lithium Metal Batteries with Solid Polymer Electrolyte

Lithium metal batteries with solid-state polymer electrolytes have garnered significant attention for their enhanced safety and high energy density. However, dendrite growth and interfacial reactions with lithium metal anodes impede their commercial viability. In this study, a LiI-coated SnLi alloy composite anode was proposed to address these critical issues. The SnLi alloy provides nucleation sites, suppressing dendrite formation, while the LiI-enriched coating reduces side reactions with the polymer electrolyte, minimizing lithium consumption. As a result, a symmetrical cell with the fabricated LiI/SnLi anode and PVDF solid polymer electrolyte (SPE) exhibits a cycling life of 2500 h. Furthermore, the LiFePO₄|PVDF-SPE|LiI/SnLi battery cycles stably over 1000 cycles. When the cathode was replaced with LiNi_0.6Co_0.2Mn_0.2O₂, the battery maintained 73.3% capacity over 600 cycles. Notably, this coin cell sustains a stable electrochemical performance even under a high loading of NCM622 (10.2 mg cm^–2) and a low N/P ratio of 4.8 over 150 cycles.