Field assisted sintering of fine-grained Li7-3xLa3Zr2AlxO12 solid electrolyte and the influence of the microstructure on the electrochemical performance

The synthesis and processing of fine-grained Li7-3xLa3Zr2AlxO12 (x = 0.15, 0.17, 0.20) solid electrolyte (LLZO) is performed for the first time using a combination of nebulized spray pyrolysis (NSP) and field assisted sintering technique (FAST). Using FAST, the grain growth is suppressed and highly dense ceramics with 93% of the theoretical density are obtained. A tetragonal lattice distortion is observed after the sintering process. Although this structural modification has been reported to have lower Li-ion mobility compared to the cubic modification, the total conductivity of the sample at room temperature is found to be 0.33 mS cm(-1), i.e. comparable to phase-pure cubic LLZO. The activation energy of 0.38 eV is also comparable to the literature values. Galvanostatic cycling of a symmetrical cell Li broken vertical bar LLZO broken vertical bar Li shows a good cycling stability over 100 h. The interfacial resistance in contact with Li-metal is determined using alternating current impedance spectroscopy to be 76 Omega cm(2) and 69 Omega cm(2) before and after cycling at different current densities, respectively. (C) 2016 Elsevier B.V. All rights reserved.