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-SO₃Li) composite electrolyte with single Li⁺ conduction was prepared by assembling lithium sulfonated COF (TpPa-SO₃Li) 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-SO₃Li electrolyte through electrostatic interaction between -NH₂/-NH- and -SO₃Li groups. This enables the construction of continuous and aligned -SO₃^- … Li⁺ … -NH₂/-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 LiFePO₄||Li and LiNi_0.8Mn_0.1Co_0.1O₂||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.