In situ bridging soft polymer and robust metal-organic frameworks as electrolyte for long-cycling solid-state potassium-organic batteries

Solid-state potassium-ion batteries (SSPIBs) are recognized as promising energy storage devices due to their cost-effectiveness and high safety. However, the reported SSPIBs generally face low ionic conductivity and poor cycling performance of solid electrolytes. Herein, we report a solid-state composite polymer electrolyte (CPE) by in-situ bridging soft polymer and robust MOF for solid-state potassium-organic batteries (SSPOBs). In this composite structure, poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) acts as a soft 3D framework to support both poly ethoxylated trimethylolpropane triacrylate (ETPTA) and UiO-66. The robust UiO-66 anchored through poly (ETPTA) can enhance the mechanical strength and chemical stability to inhibit the dendrites and widen electrochemical window. It can also increase the disorder degree of the polymers to enlarge the activity space of the polymer motion segments, thus improving the ionic conductivity. The plentiful channels inside UiO-66 can allow the transference of K⁺ whereas restrict the PF₆⁻, improving the ionic transference number. The optimized solid-state electrolyte shows a high ionic conductivity (≈3.16×10⁻⁴ S cm⁻¹), a high K⁺ transference number (0.75) and a wide electrochemical window (over 4.5 V). The assembled solid-state potassium-organic batteries (3,4,9,10-perylene-tetracarboxylicacid-dianhydride (PTCDA)|CPE|K) exhibit excellent cycling stability and rate performance, manifesting its feasibility in long-cycling solid-state potassium-ion batteries.