Ionic conductivity of LiHf2(PO4)3 with NASICON-type structure and its possible application as electrolyte in lithium batteries

Abstract

The ionic conductivity of LiHf2(PO4)3 calcined at 1100°C has been measured. Grain interior and grain boundary responses can be distinguished in the impedance plots as well as in the real part of conductivity vs frequency plots. The activation energy associated with the motion of Li+ ions inside the grains is 0.33 eV while the activation energy corresponding to the total dc conductivity changes from 0.36 to 0.47 eV, depending on the relative contribution of grain interior and grain boundary. The possible application of LiHf2(PO4)3 as an electrolyte has been tested in the Li/LiHf2(PO4)3/LiMn2O4 cell. The equilibrium potential increases from 0.076 V to 2.217 V when the temperature is raised from 28 to 148°C. © 1997 Soc. Bras. Química.