A fluorophosphate glass–ceramic electrolyte with superior ionic conductivity and stability for Na-ion batteries

Abstract

All solid-state sodium-ion electrolytes have attracted increasing attention due to their wide range of applications in secondary batteries. Here, a new fluorophosphate glass–ceramic electrolyte, (Na₂O + NaF)–TiO₂–B₂O₃–P₂O₅–ZrF₄ (NTBPZ), has been proposed and synthesized. Due to a low activation energy of 13.9 kJ mol⁻¹ and reduced resistance at the grain boundaries, the NTBPZ glass ceramic has a room-temperature ionic conductivity as high as 3 × 10⁻⁵ S cm⁻¹. In addition, the NTBPZ electrolyte has excellent thermal and chemical stabilities under ambient conditions. These outstanding performances make the NTBPZ a promising electrolyte for all-solid-state sodium-ion batteries.