High-performance all-solid-state batteries enabled by salt bonding to perovskite in poly(ethylene oxide)

Flexible and low-cost poly(ethylene oxide) (PEO)-based electrolytes are promising for all-solid-state Li-metal batteries because of their compatibility with a metallic lithium anode. However, the low room-temperature Li-ion conductivity of PEO solid electrolytes and severe lithium-dendrite growth limit their application in high-energy Li-metal batteries. Here we prepared a PEO/perovskite Li3/8Sr7/16Ta3/4Zr1/4O₃ composite electrolyte with a Li-ion conductivity of 5.4 × 10−5 and 3.5 × 10−4 S cm−1 at 25 and 45 °C, respectively; the strong interaction between the F⁻ of TFSI⁻ (bistrifluoromethanesulfonimide) and the surface Ta5+ of the perovskite improves the Li-ion transport at the PEO/perovskite interface. A symmetric Li/composite electrolyte/Li cell shows an excellent cyclability at a high current density up to 0.6 mA cm−2. A solid electrolyte interphase layer formed in situ between the metallic lithium anode and the composite electrolyte suppresses lithium-dendrite formation and growth. All-solid-state Li|LiFePO₄ and high-voltage Li|LiNi0.8Mn0.1Co0.1O₂ batteries with the composite electrolyte have an impressive performance with high Coulombic efficiencies, small overpotentials, and good cycling stability.