Tailoring the interaction of covalent organic framework with the polyether matrix toward high-performance solid-state lithium metal batteries

Abstract

Solid polymer electrolyte is one of the most promising avenues to construct next-generation energy storage systems with high energy density, high safety, and flexibility, yet the low ionic conductivity at room temperature and poor high-voltage tolerance have limited their practical applications. To address the above issues, we design and synthesize a highly crystalline, vinyl-functionalized covalent organic framework (V-COF) rationally grafted with ether-based segments through solvent-free in situ polymerization. V-COF can afford a fast Li+ conduction highway along the one-dimensional nanochannels and improve the high-voltage stability of ether-based electrolytes due to the rigid and electrochemically stable networks. The as-formed solid-state electrolyte membranes demonstrate a superior ionic conductivity of 1.1 × 10−4S cm−1 at 40°C, enhanced wide electrochemical window up to 5.0 V, and high Young's modulus of 92 MPa. The Li symmetric cell demonstrates ultralong stable cycling over 600 h at a current density of 0.1 mA cm−2 (40°C). The assembled solid-state Li|LiFePO4 cells show a superior initial specific capacity of 136 mAh g−1 at 1 C (1 C = 170 mA g−1) and a high capacity retention rate of 84% after 300 cycles. This study provides a novel and scalable approach toward high-performance solid ether-based lithium metal batteries.