Synthesis and characterization of high ionic-conductive sodium beta-alumina solid electrolyte derived from boehmite

Abstract

In this work, sodium beta-alumina solid electrolytes with high β″-Al2O3 content and high density are synthesized through solid-state reaction method employing boehmite as alumina sources. The influences of sodium oxide dosage on the phase component, texture structure, and ionic conductivity as well as the application performances in sodium ions battery for the synthesized beta-alumina electrolytes are investigated in detail. High β″-Al2O3 content of 94.6% and density of 97.8% are obtained for the electrolyte sinters through adding suitable excess of Na2O content, owing to the compensation of Na loss and the formation of molten state during the high-temperature sintering process. High ion conductivity of 1.16 × 10−2 S/cm at 350 °C is recorded for the beta-alumina electrolyte sinters, resulting from its high β″-Al2O3 content and density. The resultant beta-alumina electrolyte applied in Na3V2(PO4)3/Na battery delivers an initial discharge capacity of 80.5 mAh g−1 at 0.5 C and a high capacity retention of 79.25% after 100 cycles.