SnF₂-Induced Multifunctional Interface-Stabilized Li_5.5PS_4.5Cl_1.5-Based All-Solid-State Lithium Metal Batteries

Compared to traditional lithium-ion batteries with liquid electrolytes, all-solid-state lithium batteries have attracted extensive attention due to their heightened safety and energy density. Lithium argyrodite materials are promising solid electrolytes (SE) due to their high ionic conductivity, low grain boundary resistance, and favorable mechanical properties. However, the poor chemical/electrochemical stability of lithium argyrodite electrolytes toward the bare lithium metal anode inhibits their applications in all-solid-state lithium metal batteries (ASSLMBs). Here, Li-SnF₂ composite anodeswas used to induce the formation of solid electrolyte interphase (SEI) composed of LiCl, LiF, and Li₂₂Sn₅ at the Li/SE interface.  The high interface energy barriers for LiF and LiCl induces the uniform deposition of lithium ions, thus hindering the growth of lithium dendrites. Meanwhile, the fast Li-ion diffusion coefficient of the Li₂₂Sn₅ alloy accelerates Li-ion migration across the interface section. The symmetrical cell exhibits stable cycling performance over long durations over 300 h at 0.5 mA cm⁻². Moreover, the LiNbO₃@NCM712/Li_5.5PS_4.5Cl_1.5/Li-10%SnF₂ battery delivers a high initial discharge capacity of 170.9 mAh g⁻¹ at 0.1C and retains 72.9% of its original capacity after 500 cycles at 0.5C. The facial approach for Li-SnF₂ composite anode enables the production of ASSLMBs with superior electrochemical performance.