Molecular Interfacial Engineering of Sulfide Electrolytes via R134a Gas–Solid Reaction Toward Low-Pressure All-Solid-State Lithium Metal Batteries

The practical application and large-scale production of all-solid-state batteries urgently require electrolyte materials with high interface stability. Although sulfide solid electrolytes have the advantages of high ionic conductivity and good processability, their interface chemical instability and lithium dendrite growth seriously restrict the electrochemical performance in batteries, especially under low external pressure. Herein, a molecular-scale interface engineering strategy based on R134a refrigerant is proposed to perform in situ surface modification of Li6PS5Cl (LPSC). By controlling the contact between a certain concentration of CF3CH2F (R134a) and LPSC, a nanoscale LiF-rich interface layer with high hydrophobicity and excellent antioxidant capacity is constructed. The well-designed interface can effectively suppress parasitic reactions, uniform the Li-ion flux, and significantly improve the air stability of the electrolyte. The optimized LPSC (LPSC@R134a) exhibits a dendrite inhibition ability with a high critical current density up to 4.27 mA cm–2. The lithium-symmetrical battery assembled based on it achieves a stable cycle of more than 500 h at 4 mA cm–2. The full cell matched with the high-voltage NCM811 cathode has a stable cycle of 0.5C for more than 700 cycles under low external pressure conditions. This work solves the problem of interface and contact stability simultaneously through molecular-scale interface design, paving an effective route to construct high-performance and low external pressure all-solid-state lithium metal batteries.