Effect of intermolecular interactions on the performance of UiO-66-laden solid composite polymer electrolytes

Solid composite polymer electrolytes have been proposed as high-performance solid electrolytes for next-generation energy storage devices. In particular, UiO-66 with monodispersed size (400 nm) and morphology and outstanding stability was introduced as a functional filler to modify the electrochemical properties of poly(ethylene oxide) (PEO) solid electrolytes with LiClO₄ as the lithium salt. The desired physicochemical properties and electrochemical properties of the electrolyte was improved through microstructure regulation and the intermolecular interactions, as confirmed by X-ray diffraction, differential scanning calorimetry, optical microscopy and electrochemical characterisation. Owing to the intermolecular interactions, crystallisation of PEO was inhibited, and the ionic conductivity of the solid composite polymer electrolyte increased to 4.8 × 10⁻⁵ S cm⁻¹ at 25 °C. Electrochemical stable window and lithium ion transference number (t₊) were also observably enhanced. The assembled LiFePO₄/PEO-LiClO₄-UiO-66/Li solid-state lithium batteries exhibited excellent cycling and C-rate performances. The initial discharge capacity reached to 160 mAh g⁻¹, and superior cycle stability with a capacity retention ratio of 83% after 200 cycles at 1C current and 80 °C was achieved. The discharge capacity at 5C was improved by 232%. This work provides new insights into boosting the performances of solid composite polymer electrolytes through intermolecular interactions.