ScholarWorks@경상국립대학교

초록

Na β″-alumina (Na2O·5-7Al2O3) is widely recognized as a high-performance solid electrolyte for sodium-metal chloride batteries due to its excellent sodium ion conductivity (0.2-0.4 S cm−1 at 300 °C) and thermal stability. With growing demand for intermediate-temperature operation (<200 °C) to minimize cathode degradation and enable polymer sealing, maintaining sufficient ionic transport through the electrolyte becomes a critical challenge. To address this, we employed a vapor phase conversion method to fabricate Na β″-alumina/YSZ (yttria-stabilized zirconia) composites by reacting α-Al2O3/YSZ tapes with Na2O vapor. Although >30 vol% YSZ is required for full conversion, this can obstruct sodium ion pathways and reduce conductivity. To overcome this limitation, we developed a novel core-shell structured electrolyte in which the outer “Shell” regions comprising approximately 10% of total thickness, are enriched with >90 vol% of Na β″-alumina, compared to 70 vol% in the core. This design promotes efficient ion transport across the electrolyte, offering a promising route toward high-performance Na-MeCl2 batteries operating below 200 °C. © 2026 Elsevier Ltd and Techna Group S.r.l. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

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