Dielectric LiNbO3 electrolyte regulating internal electric field in composite solid-state electrolyte to fundamentally boost Li-ion transport

The composite solid-state electrolytes (CSEs) are one of the most promising electrolytes for advanced solid-state Li metal batteries. However, it is unclear for the effect of the induced electric field inside CSEs on the Li-ion transport. Herein, we design a compact CSE by imbedding the lithium niobate (LiNbO3) with both high ionic conductivity and dielectric constant into poly(vinylidene fluoride) matrix (NPC). The LiNbO3 significantly enhances the internal electric field of NPC along the LiNbO3 particles and establishes uniform interfacial electric field between NPC and electrodes, which fundamentally facilitates the Li-ion transport, weakens the space-charge layer and inhibits the growth of Li dendrites. Continuous fast ion-conducting channels with high concentration of Li-ions are constructed inside NPC, which contributes to a quite high ionic conductivity (7.39×10−4 S cm−1, 25°C) and ultra-low activation energy (0.112 eV). The LiNi0.8Co0.1Mn0.1O2/NPC/Li solid-state batteries exhibit quite stable cycling performance at 25°C.