Effects of synthetic conditions on the structural, stability and ion conducting properties of Li0.30(La0.50Ln0.50)0.567TiO3 (Ln= La, Pr, Nd) solid electrolytes for rechargeable lithium batteries

The structure, thermal stability, morphology and ion conductivity of titanium perovskites with the general formula Li3xLn2/3−xTiO3 (Ln = rare earth element; 3x= 0.30) are studied in the context of their possible use as solid electrolyte materials for lithium ion batteries. Materials are prepared by a glycine-nitrate method using different sintering treatments, with a cation-disorder-induced structural transition from tetragonal to cubic symmetry, detected as quenching temperature increases. SEM images show that the average grain size increases with increasing sintering temperature and time. Slightly higher bulk conductivity values have been observed for quenched samples sintered at high temperature. Bulk conductivity decreases with the lanthanide ion size. A slight conductivity enhancement, always limited by grain boundaries, is observed for longer sintering times. TDX measurements of the electrolyte/cathode mixtures also show a good stability of the electrolytes in the temperature range of 30-1100ºC.This research has been funded by the Consejería de Industria, Innovación, Comercio y Turismo (SAIOTEK 2012 programmes), by Dpto. Educación, Política Lingüística y Cultura of the Basque Goverment (Grupos de Investigación del Sistema Universitario Vasco 2013 – 2018; IT-630-13), by Ministerio de Ciencia e Innovación (MAT2010-15375 and MAT2012-30763) and by Ministerio de Economía y Fondos Feder (MAT2010-19837-C06-06). The authors thank SGIker technical support (UPV/EHU, MEC, GV/EJ and European Social Fund). L.O.S.M. acknowledges the Departamento Ciencias, PUCP, for the allocation of research time