Enhanced ionic conductivity in planar sodium-β"-alumina electrolyte for electrochemical energy storage applications.
Solid Na-β"-Al₂O₃ electrolyte is prepared by a simple chemical route involving a pseudo-boehmite precursor and thermal treatment. Boehmite powder is used for manufacturing the planar electrolyte with appropriate bulk density after firing at 1500 °C. The structure, morphology, and surface properties of precursor powders and sintered electrolytes are investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). As shown by XRD and TEM analyses, nanometer-sized particles are obtained for the boehmite precursor and a pure crystallographic phase is achieved for the sintered electrolyte. SEM analysis of the cross-section indicates good sintering characteristics. XPS shows a higher Na/Al atomic ratio on the surface for the planar electrolyte compared to a commercial tubular electrolyte (0.57 vs. 0.46). Energy-dispersive X-ray microanalysis (EDX) shows an Na/Al ratio in the bulk of 0.16, similar in the two samples. The ionic conductivity of the planar electrolyte is larger than that measured on a commercial tube of sodium-β"-alumina in a wide temperature range. At 350 °C, conductivity values of 0.5 S cm⁻¹ and 0.26 S cm⁻¹ are obtained for the planar electrolyte and the commercial tube, respectively. AC-impedance spectra show smaller grain boundary effects in the planar electrolyte than in the tubular electrolyte. These favorable properties may increase the perspectives for applying planar Na-β"-Al₂O₃ electrolytes in high-temperature batteries.
CNR-ITAE Institute, Consiglio Nazionale delle Ricerche, Messina, Italy.
Daniela
D
La Rosa
Giuseppe
G
Monforte
Claudia
C
D'Urso
Vincenzo
V
Baglio
Vincenzo
V
Antonucci
Antonino S
AS
Aricò
D000537:Aluminum Oxide / Q000737:chemistry*; D004553:Electric Conductivity; D011211:Electric Power Supplies; D055664:Electrochemical Techniques; D004573:Electrolytes / Q000138:chemical synthesis* / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D056951:Photoelectron Spectroscopy; D012964:Sodium / Q000737:chemistry*; D013499:Surface Properties; D014961:X-Ray Diffraction
D004573:Electrolytes; D012964:Sodium; D000537:Aluminum Oxide