Preparation and characterization of large area Li-NASICON electrolyte thick films

Nowadays the interest in the development of electrochemical devices based on solid electrolytes is increasing. Due the limited ionic conductivity of the solids in comparison with its counterpart, liquid electrolytes, the... [ view full abstract ]

Nowadays the interest in the development of electrochemical devices based on solid electrolytes is increasing. Due the limited ionic conductivity of the solids in comparison with its counterpart, liquid electrolytes, the procurement of large area solid electrolytes as thin as possible (thick films) is of main interest to develop competitive devices. In this communication the preparation of large area (5.5 x 5.5 cm²) ceramic self-standing thick films of Li- NASICON with composition Li_1.3Ti_1.7Al_0.3(PO₄)₃ by tape casting is attempted. A complete characterization of the samples including structural, microstructural, mechanoelastic  features as well as NMR and broad-band impedance has been performed. The departure from the nominal composition of thick films, was estimated from quantitative analysis of  ³¹P MAS-NMR spectra. Distribution of octahedral cations was deduced from intensities of P NMR components and distribution of different phases present in the samples  deduced using confocal  Raman spectroscopy. The effect of the different preparation procedures on phase composition,   homogeneity, microstructures and physical properties is discussed. Special emphasis is made on the effects of the preparation on both the grain boundary and the "bulk" conductivity response of the Li-NASICON as well as the relationship between the observed microstructure (grain size distribution)  and the mechano-elastic properties. The results obtained  will be compared with those found out in the literature in self-standing thick films and supported ones [1]. In the best sample, the reported total Li conductivity measured (>10^-4 Scm^-1) is close to that of the commercial Li-NASICON thick films samples from OHARA.

References:

[1] R. Jiménez. et al. Journal of the European Ceramic Society, 2017. https://doi.org/10.1016/j.jeurceramsoc.2017.12.017.

Supported by Spanish Projects PCIN-2017-110 (M-ERA-NET) and MAT2016-78362-C4-2-R.