Structural Studies and Ionic Conductivity of Lithium Iodide-Lithium Tungstate Solid Electrolytes

Solid mixtures of calcined lithium iodide - lithium tungstate (LiI - Li(2)WO(4)) have been found to be potential solid electrolytes for practical applications with high conductivities of about 10(-3) S.cm(-1) at room temperature. The highest ionic conductivity was recorded for the sample containing 20 wt.-% of lithium iodide. The ionic conductivity was related to the structure of the material using X-ray diffraction (XRD) and infrared techniques (FTIR). These experiments confirm the evidence of interaction between LiI and Li(2)WO(4). FTIR spectroscopy revealed the existence of a band at 1505 cm(-1) which is formed as a result of this LiI - Li(2)WO(4) interaction. The new phase acts as a conducting pathway for the ions to migrate through the material. Lithium ionic conduction was confirmed by measuring the transference number by Wagner's polarization technique. The ionic transference number of this solid electrolyte was found to be 1 within the limits of error.