Competitive Li-ion Coordination Constructing Three-Dimensional Transport Network for Ultra-High Ionic Conductivity of Composite Solid-State Electrolyte

Abstract

The porous structure of poly(vinylidene fluoride) (PVDF)-based polymer electrolytes and their disordered ion transport properties restrict the continuous and highly efficient transport of lithium ion (Li+), which exists as the major challenge to further improve the ionic conductivity. Herein, we construct a compact composite solid-state electrolyte with a three-dimensional continuous Li+ transport network by coupling heat-treated polyacrylonitrile fiber network with interconnected metal organic framework coating layer (h-PAN@MOF). The MOF crystal surface exhibits strong interactions with C=O of N,N-dimethylformamide (DMF), which effectively weakens the Li+-O binding strength of DMF in Li+ solvation structure. Highly efficient Li+ transport channels and networks are constructed to achieve a high ionic conductivity of 1.03×10–3 S cm–1. The MOF-participated Li+ coordination environment prompts the formation of a stable interphase. The h-PAN@MOF network also contributes to a high tensile strength (20.84 MPa) of the compact electrolyte. The Li||LiNi0.8Mn0.1Co0.1O2 full cells with h-PAN@MOF network realize robust cycling for 1000 times at 5C. This work provides a facile strategy of regulating the Li+ coordination state and its spatial distribution in solid-state electrolytes for fast-charging solid-state Li metal batteries.