Li₂ S₆ -Integrated PEO-Based Polymer Electrolytes for All-Solid-State Lithium-Metal Batteries

The integration of Li₂ S₆ within a poly(ethylene oxide) (PEO)-based polymer electrolyte is demonstrated to improve the polymer electrolyte's ionic conductivity because the strong interplay between O^2- _(PEO) and Li⁺ from Li₂ S₆ reduces the crystalline volume within the PEO. The Li/electrolyte interface is stabilized by the in situ formation of an ultra-thin Li₂ S/Li₂ S₂ layer via the reaction between Li₂ S₆ and lithium metal, which increases the ionic transport at the interface and suppresses lithium dendrite growth. A symmetric Li/Li cell with the Li₂ S₆ -integrated composite electrolyte has excellent cyclability and a high critical current density of 0.9 mA cm^-2 at 40 °C. Impressive electrochemical performance is demonstrated with all-solid-state Li/LiFePO₄ and high-voltage Li/LiNi_0.8 Mn_0.1 Co_0.1 O₂ cells at 40 °C.