Factors affecting ionic conductivity in the lithium conducting glassy solid electrolytes

The electrical conductivity results of lithium borosilicate glasses with addition of Li₂SO₄ and LiCl have been critically analyzed. In general, it is observed that the factors viz. lithium fraction, f_Li and the number of non-bridging oxygens (NBOs) govern the ionic conductivity in the lithium conducting glasses. For the same f_Li, the presence of mixed formers in the glass gives higher conductivity compared to that of the glass with only one former. Thus the competitive network of glass in mixed former systems provides higher mobilities for lithium ions and hence high ionic conductivity. The addition of Li₂SO₄ and LiCl in the lithium borosilicate glasses gave enhancement in the conductivity. However, the mechanism of enhancement in conductivity is different in the two glass systems. The comparison of the result of binary, ternary and quaternary glass systems suggests that in general, the decrease in activation energy, increase in f_Li and increase in NBOs gives rise to enhancement in conductivity. For the same value of f_Li the higher conductivity is exhibited by glasses with lower value of K (K=SiO₂/B₂O₃). Paper presented at the 2nd International Conference on Ionic Devices, Anna University, Chennai, India, Nov. 28–30, 2003.