Versatile Strategy for Realizing Flexible Room-Temperature All-Solid-State Battery through a Synergistic Combination of Salt Affluent PEO and Li6.75La3Zr1.75Ta0.25O12 Nanofibers

All-solid-state lithium metal batteries are highly attractive because of their high energy density and inherent safety. However, it is still a great challenge to design the solid electrolytes with high ionic conductivity at room temperature and good electrode/electrolyte interfacial compatibility simultaneously in a facile and scalable way. In this work, for the first time, the combination of salt affluent Poly(ethylene oxide) with Li6.75La3Zr1.75Ta0.25O12 nanofibers was designed and intensively evaluated. The synergistic effect of each component in the electrolyte enhances the ionic conductivity to 2.13 × 10–4 S cm–1 at 25 °C and exhibits a high transference number of 0.57. The composite electrolyte possesses superior interfacial stability against Li metal for over 680 h in Li symmetric cells even at a relatively high current density of 2 mA cm–2. The all-solid-state batteries employing the solid electrolytes exhibit excellent cycling stability at room temperature and superior safety performance. This work proposes a brand-new strategy to design and fabricate solid electrolytes in a versatile way for room-temperature all-solid-state batteries.