Construction of excellent solid-state electrolyte by incorporating Li-IL into open-pore MOF/polymer-based materials

Abstract

Metal–organic framework (MOF)/polymer-based composites are frequently utilized in solid-state electrolytes because of because of the high interfacial compatibility of polymers and the ion-screening ability of MOFs. They are alse often combined with ionic liquids (ILs) to form composite solid-state electrolytes (CSEs). However, the conventional method of combining these components sacrifices some of their individual excellent properties. In this work, the HKUST-1 (Cu) and polyacrylonitrile (PAN) polymer were efficiently combined to create pore-exposed HKUST-1/PAN fibers. Subsequently, the Li-IL@HKUST-1/PAN CSE was obtained by introducing ILs containing lithium salt (Li-IL) into the pores of HKUST-1. At 25 °C, the synthesized CSE exhibited an ionic conductivity of 2.40 × 10⁻³ S cm⁻¹ and a lithium-ion mobility number of 0.698. Furthermore, this CSE enables the assembly of LiFePO₄/Li solid-state batteries with outstanding cycling performance and multiplicity ranging from 0.1C to 5C at room temperature, with a stable reversible capacity of 67.5 mA h g⁻¹ after 100 cycles at a high current density of 5C (25 °C) with a capacity retention of 94.1%. The electrochemical performance of Li-IL@HKUST-1/PAN is significantly superior to that of the conventional Li-IL/HKUST-1/PAN, which can be attributed to the effective combination of HKUST-1, PAN and Li-IL. This combination allows each component to fully exhibit its advantages and synergistically enhances the overall performance, facilitating the selective and rapid transport of lithium ions. This study presents new opportunities for multi-component composite solid-state electrolytes with high performance.