Lamellar COF solid-state electrolytes for robust ambient-temperature lithium-ion transfer enhanced by PEI-driven channel alignment

Ionic covalent organic framework (COF) lamellar membranes are the alternative materials as promising Li + conductors for all-solid-state lithium batteries. However, COF lamellar membrane suffers from poor structural stability and inevitable cross-layer transfer resistance due to the weak interaction at interface of adjacent nanosheets. Herein, a lamellar polymer-threaded ionic COF (PEI@TpPa-SO 3 Li) composite electrolyte with single Li + conduction was prepared by assembling lithium sulfonated COF (TpPa-SO 3 Li) nanosheets and then threading them with polyethyleneimine (PEI) chains. It reveals that the threaded PEI chains induce the oriented permutation of pore channel of PEI@TpPa-SO 3 Li electrolyte through electrostatic interaction between –NH 2 /−NH− and –SO 3 Li groups. This enables the construction of continuous and aligned –SO 3 − … Li + … −NH 2 /−NH− pairs along pore channels, which act as efficient Li + conducting sites and afford high Li + hopping conduction (1.4 × 10 −4 S cm −1 at 30 °C) with a high Young's modulus of 408.7 MP and wide electrochemical stability window of 0∼4.7 V. The assembled LiFePO 4 ||Li and LiNi 0.8 Mn 0.1 Co 0.1 O 2 ||Li half-cells achieve high discharge capacities of 155.0 mAh g −1 and 167.2 mAh g −1 at 30 °C under 0.2 C, respectively, with high capacity retention of 98% after 300 cycles. This study provides an alternative route to highly ion-conductive lamellar porous electrolytes for high-performance energy devices. A thin lamellar polymer-threaded ionic COF (PEI@TpPa-SO 3 Li) composite electrolyte was designed by assembling lithium sulfonated COF (TpPa-SO 3 Li) nanosheets and then threading them with polyethyleneimine (PEI) chains, where the pore channel was orderly aligned through electrostatic interaction between –NH 2 /−NH− and –SO 3 Li groups, constructing continuous and aligned transfer pathways and enabling fast lithium-ion transport and high cell performances at 30 °C. • Lamellar polymer-threaded COF electrolyte was prepared by two-step filtration. • Threaded PEI chains trigger oriented permutation of pore channel of COF framework. • The polymer-threaded structure forms continuous pathway for high Li + conduction. • The electrolyte presents excellent mechanical property and electrochemical stability. • Assembled LiFePO 4 ||Li and NCM 811||Li cells show high cycling stability at 30 °C.