Replacing organic porous separators with an inorganic solid-state electrolyte (SSE) is a promising strategy to suppress lithium dendrite and inhibit polysulfide dissolution in lithium-sulfur (Li-S) batteries. However, the realization of such a concept is still limited by the large interfacial resistance between SSE and lithium anode. Herein, a new electrolyte additive, copper fluoride (CuF2), is used in liquid electrolytes to construct a stable interphase between Li1.5Al0.5Ge1.5(PO4)3 (LAGP) SSE and Li metal for a quasi-solid-state Li-S battery. A Li||Li symmetric cell with ultralong life over 1500 h (at 0.1 mA cm-2) proves the excellent stability of the as-formed interphase. As a result, the assembled Li-S full cell presents high coulombic efficiency and stable cycling (750 mA h g-1 after 50 cycles) at room temperature with lean liquid electrolytes. This strategy provides an effective method for improving the electrochemical performance of Li-S batteries.
Keywords: copper fluoride; interface; lithium metal anode; lithium−sulfur batteries; quasi-solid-state batteries.