Li-ion conductivity and electrochemical stability of A-site deficient perovskite-structured Li_(3x-y)La_(1-x)Al_(1-y)Ti_yO_3 electrolytes

摘要

Perovskite-type Li3x-yLa1-xTiyO3 (x = 5y/12) solid electrolytes with varying Ti content (y = 0.4, 0.6, 0.8, 0.9, and 1) were prepared by conventional solid-state reaction process. Furthermore, the crystal structure, Li-ion conductivity, and electrochemical stability were investigated by X-ray diffraction, alternating current impedance, and cyclic voltammetry. X-ray diffraction analysis showed minimum impurities and a change from cubic to tetragonal with increasing Ti content. Maximum bulk and total conductivities of 1.99 x 10(-3) S cm(-1) and 4.53 x 10(-4) S cm(-1) were obtained in Li0.25La0.583TiO3, with activation energy of 0.28 eV and electronic conductivity of 2.30 x 10(-9) S cm(-1) at 20 degrees C. Cyclic voltammetry showed that Al-contained materials such as Li0.2La0.667Al0.2Ti0.8O3, and Li0.225La0. 625Al0.1Ti0.9O3 were slightly more stable than Li0.25La0.583TiO3 vs. Li+/Li. LiFePO4/Li batteries were fabricated using Li0.225La0.625Al0.1T0.9O3, and Li0.25La0.583TiO3 as solid electrolyte separators, a capacity of 79.0, and 112.0 mA hg(-1) at 25 degrees C were maintained over 100 cycles, respectively.