Exploring the synergistic potential of PVB: KCl composite electrolyte films for enhanced performance in solid-state potassium batteries

Polyvinyl butyral (PVB) integrated with varying compositions of potassium chloride (KCl) was prepared through a solution-cast method in methanol, forming a PVB-based electrolyte film for solid-state potassium batteries. The incorporation of KCl into PVB matrix significantly altered the composite electrolyte film’s structural intricacies, bandgap modulation, thermal stability and facilitated functional group identification. Furthermore, the ionic conductivity of the PVB polymer electrolyte exhibited an initial enhancement followed by a subsequent reduction with the escalating ratio of KCl. Specifically, at 80 wt% PVB and 20 wt% KCl, its ionic conductivity reached a value of 1.87 × 10⁻⁵ S cm⁻¹ at room temperature and 9.61 × 10⁻⁵ S cm⁻¹ at 303 K temperature. The ion transference number, which denotes the relative ease with which potassium ions migrate within the PVB polymer-complexed electrolyte, was determined to be 0.98. Discharge tests on the cell, under 1.2 µA current and 2.1 V at room temperature, displayed an initial 9.16 µA h⁻¹ discharge capacity.