Inter-grain Li+ conduction in Sc and Y doped LATP compounds

• Published in: Physica. B, Condensed matter Vol. 627; p. 413599
• Main Authors: Kothari, Dharmesh H., Kanchan, D.K.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15-02-2022; Elsevier BV
• Subjects: Conductivity; Dopant; Electrochemical impedance spectroscopy; Frequency ranges; Grain boundaries; Grain size; LATP; Li grain boundary conductivity; Scanning electron microscopy; Solid state physics; Space charge; Yttrium; Space charge; Dopant; LATP; Li grain boundary conductivity
• ISSN: 0921-4526; 1873-2135
• DOI: 10.1016/j.physb.2021.413599

Low value of grain boundary conductivity in Li-NASICON materials is an important limitation that needs to be overcome. Inter-grain conduction of Li + ions in Li1·3Al0.3-xScxTi1.7(PO4)3 (LASTP) and Li1·3Al0.3-xYxTi1.7(PO4)3 (LAYTP) (where x = 0.01 and 0.07) samples is investigated. The samples, prepared by solid state reaction method, were characterised by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. Electrochemical Impedance Spectroscopy (EIS) was performed in the frequency range of 20 MHz to 1 Hz, and temperature range of 20 °C–100 °C. The grain boundary impedance and capacitance was found to vary with an external dc bias voltage. Higher grain boundary conductivity was found for sample containing higher yttrium concentration. Effect of space charge on grain boundary conductivity is evaluated in light of two competing models.
•Grain boundary conductivity in scandium and yttrium doped Li-Al-Ti-P (LATP) material is studied.•LiTi2(PO4)3 (LTP) was identified as the primary Li+ ion conducting phase. It belongs to R-3c space group. Small amounts of secondary phases were also identified.•Accumulated ions rather than depleted charges from grain boundary core form space charge at grain boundary.