Synthesis and characterization of high ionic-conductive sodium beta-alumina solid electrolyte derived from boehmite
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Synthesis and characterization of high ionicconductive sodium beta-alumina solid electrolyte derived from boehmite Zehua Liu1, Jingjing Chen1,*, Xinxin Wang1, Yingqi Wang2, Dajian Wang2, and Zhiyong Mao2,* 1
Tianjin Key Laboratory for Photoelectric Materials and Devices, School of Materials Science and Engineering, Tianjin University of Technology, Tianjin 300384, China 2 Key Laboratory of Display Materials and Photoelectric Devices, Ministry of Education, Tianjin University of Technology, Tianjin 300384, China
Received: 28 June 2020
ABSTRACT
Accepted: 21 August 2020
In this work, sodium beta-alumina solid electrolytes with high b00 -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 b00 -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 9 10-2 S/cm at 350 °C is recorded for the beta-alumina electrolyte sinters, resulting from its high b00 -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.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Sodium beta-alumina electrolyte has been widely applied in large-scale energy-storage systems, such as high-temperature Na–S [1] and ZEBRA batteries [2], due to its high sodium ion conductivity and excellent thermal properties. Sodium beta-alumina is commonly recognized as the compounds having the
formula of Na2OnAl2O3, in which n is between 5 and 11 typically. These compounds deliver high sodium mobility along the conductive planes within their layered structure. According to the different ratio of sodium to aluminum, there are two structural modifications for the beta-alumina, namely hexagonalstructure b-Al2O3 and rhombohedral-structure b00 Al2O3 with the stoichiometry of Na2O(8–11)Al2O3
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https://doi.org/10.1007/s10854-020-04321-7
J Mater Sci: Mater Electron
and Na2O(5–7)Al2O3, respectively [3, 4]. Both of the two crystal structures are constructed by alternatively stacked conductive planes and spinel blocks. The difference of them is that b00 -Al2O3 consists three spinel blocks bonded via two conductive planes while b-Al2O3 has two spinel blocks and one conductive plane. The more much conductive planes and larger sodium content in conductive planes of b00 Al2O3 phase result in the 3–4 times higher ionic conductivity than that of b-Al2O3 [5–7].
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