| Abstract Scope |
Potassium solid-state electrolytes (SSEs) offer improved safety and higher energy density to potassium-ion batteries. However, there are few potassium SSEs with ionic conductivity high enough for use in batteries (>10-4 S/cm). Herein, we demonstrate a new potassium SSE, khibinskite, with empirical formula K2ZrSi2O7. Khibinskite, a rare mineral found in the Kola Peninsula, Russia, is formed of alternating layers of ZrO6 octahedra and Si2O7 dimers. Interstitial potassium cations occupy sites in the Si2O7 layer and hop through wide hexagonal bottlenecks. In this presentation, we present detailed structural characterization based on Rietveld refinements of PXRD patterns, promising ionic conductivity (~10-6 S/cm) based on electrochemical impedance spectroscopy, and a proposed conduction mechanism based on bond valence site energy analysis. Finally, we discuss ongoing efforts to improve ionic conductivity by increasing density with cold sintering techniques and introducing K+ vacancies with heterovalent doping. |