Hexagonal boron nitride-assisted fabrication of lithium-rich antiperovskite superionic conductor

Abstract

In this study, Ba-doped Li3OCl antiperovskite solid electrolytes and their hexagonal boron nitride (hBN)-reinforced composites were successfully synthesized via a hydrothermal method followed by rapid solidification. Liquid-phase exfoliated hBN nanosheets were incorporated at 2 wt.% and 5 wt.% to investigate their effects on the structure and ion transport properties. X-ray diffraction (XRD) analysis revealed a reduction in crystallinity and increased amorphous phase content in the re-melted and hBN-containing samples. Differential scanning calorimetry (DSC) showed a glass transition temperature (T-g) at similar to 97(degrees)C for the pure Ba-doped Li3OCl, which shifted to 107(degrees)C upon hBN addition, indicating enhanced thermal stability. Morphological studies confirmed hBN-enhanced densification (82% theoretical density), reducing microporosity and improving interfacial stability. Electrochemical impedance spectroscopy (EIS) revealed that the ionic conductivity of Ba-doped Li3OCl demonstrated ionic conductivities of 0.28 mS/cm (40 degrees C) and 12 mS/cm (160(degrees)C) for pure samples (Ea = 0.32 eV), while 2 wt.% hBN composites achieved 0.77 mS/cm (40 degrees C) along with the same activation energy. 0.28 mS cm(-1) at 40(degrees)C, increasing to 12 mS cm(-1) at 140(degrees)C. However, 5 wt.% hBN led to high charge-transfer resistance (130 k Omega/cm(2)), underscoring the need for optimal hBN content (<5 wt.%) to balance densification and conductivity. These results demonstrate that a small amount of hBN reinforcement supports densification, improves thermal stability and enables single-step processing, making it a promising strategy for developing antiperovskite-based electrolytes for high-performance solid-state batteries.