Effect of Li addition on structural, electrical and electrochemical properties on lanthanum manganite

The addition of aliovalent element plays an important role on the structural, electrical and electrochemical properties of LaMnO3. In this study, 10% of Li was incorporated into the A-site of the LaMnO3 perovskite. The addition of more than 10% Li resulted in the formation of the LiMn2O4 spinel as a second phase. The conductivity of LaMnO3 was also effectively enhanced by the addition of Li. The undoped LaMnO3 exhibits a conductivity of 0.25 Omega(-1) cm(-1) at 27 degrees C. In the LaMnO3 sample doped with 10% Li, the conductivity increased to 2.25 Omega(-1) cm(-1) at 27 degrees C. For 30% Li-doped LaMnO3, the lower conductivity of 1.31 Omega(-1) cm(-1) at 27 degrees C was observed due to the formation of poor-conducting LiMn2O4. In all the samples doped with Li, the activation energy (17.20-18.17 kJ/mol) for electrical conduction was much lower than that of undoped LaMnO3 (26.71 kJ/mol). The reduction in activation energy can be rationalized by the creation of electron holes due to the addition of Li. In the sample with the composition of La0.9Li0.1MnO3, the cyclic voltammetry and charge/discharge tests indicated that the sample was not electrochemically active. (c) 2004 Elsevier B.V. All rights reserved.