Field-assisted sintering of Li1.3Al0.3Ti1.7(PO4)3 solid-state electrolyte

•LATP solid electrolytes were sintered under applied DC fields.•High applied voltage increased densification, grain growth, and changed grain morphology.•Conductivity decreased with applied voltage due to grain morphology.•LATP responds differently to applied voltages during sintering than other classes of materials.

All solid Li-ion batteries display high stability and longevity but are hampered by the poor conductivity of most solid electrolytes. The influence of applied electrical fields during sintering on microstructure and electronic properties of lithium aluminum titanium phosphate (Li1.3Al0.3Ti1.7(PO4)3, LATP) electrolyte material was investigated by sintering LATP pellets under DC voltages of 0 V, 2 V, 10 V, and 20 V, followed by characterization via scanning electron microscopy (SEM) and impedance spectroscopy. The application of a DC voltage increased the relative density to a maximum of 95.5%. However, unlike reports on other material systems such as zirconia, a high DC voltage induced rather than restrained abnormal grain growth. Resistivity increased with applied voltage from 2.1 kΩ·cm at 0 V to 7.8 kΩ·cm at 20 V, which was attributed to the high faceting and poor grain to grain contact of the grains sintered under 10 V and 20 V.