A dielectric electrolyte composite with high lithium-ion conductivity for high-voltage solid-state lithium metal batteries.

The ionic conductivity of composite solid-state electrolytes does not meet the application requirements of solid-state lithium (Li) metal batteries owing to the harsh space charge layer of different phases and low concentration of movable Li ⁺ . Herein, we propose a robust strategy for creating high-throughput Li ⁺ transport pathways by coupling the ceramic dielectric and electrolyte to overcome the low ionic conductivity challenge of composite solid-state electrolytes. A highly conductive and dielectric composite solid-state electrolyte is constructed by compositing the poly(vinylidene difluoride) matrix and the BaTiO ₃ -Li _0.33 La _0.56 TiO _3-x nanowires with a side-by-side heterojunction structure (PVBL). The polarized dielectric BaTiO ₃ greatly promotes the dissociation of Li salt to produce more movable Li ⁺ , which locally and spontaneously transfers across the interface to coupled Li _0.33 La _0.56 TiO _3-x for highly efficient transport. The BaTiO ₃ -Li _0.33 La _0.56 TiO _3-x effectively restrains the formation of the space charge layer with poly(vinylidene difluoride). These coupling effects contribute to a quite high ionic conductivity (8.2 × 10 ^-4  S cm ^-1 ) and lithium transference number (0.57) of the PVBL at 25 °C. The PVBL also homogenizes the interfacial electric field with electrodes. The LiNi _0.8 Co _0.1 Mn _0.1 O ₂ /PVBL/Li solid-state batteries stably cycle 1,500 times at a current density of 180 mA g ^{- 1} , and pouch batteries also exhibit an excellent electrochemical and safety performance.
(© 2023. The Author(s), under exclusive licence to Springer Nature Limited.)