Building cross-phase ion transport channels between ceramic and polymer for highly conductive composite solid-state electrolyte

The large energy barrier for lithium-ion transport across polymer-ceramic interface limits the significant improvement of the ionic conductivity of composite solid-state electrolytes (CSEs). Herein, we construct high-efficiency cross-phase ion transport channels (CITCs) between poly(vinylidene fluoride) (PVDF) and Li6.4La3Zr1.4Ta0.6O12 (LLZTO) by cross-linking reaction of 3-methacryloxypropyltrimethoxysilane (MPS) with dehydrofluorinated PVDF and LLZTO. The CITCs enhance the lithium-ion concentration at the PVDF-LLZTO interface and provide continuous low-barrier lithium-ion pathways to achieve a quite high ionic conductivity (8.7 × 10−4 S cm−1) of CSE (PML). Furthermore, we quantitatively reveal that the CITCs increase the proportion of interfacial lithium-ion transport in CSEs from 4.2% to 26.2%, which further promotes the lithium-ion transport contribution of LLZTO from 8.6% to 18.2%. LiNi0.8Co0.1Mn0.1O2|PML|Li solid-state batteries can stably operate for 1,700 cycles at 2C and 25°C, and pouch cells also exhibit excellent cycling and safety performance. This work reveals that cross-phase lithium-ion transport in CSEs determines their ionic conductivity.