Development of glass-polymer composite electrolytes for Li-ion cells

A new type of solid-state electrolyte, the glass-polymer composite (GPC) electrolyte, has been developed. The electrochemical behavior of the GPC, consisting of 100-x vol% 0.54 Li₂S·0.21 B₂S₃·0.25 LiI glass and x vol% P(EO)₈ ·LiN(CF₃SO₂)₂ polymer with x=7, 13, and 25, has been investigated. Results show that the addition of polymer to the glass powder increases not only the mechanical flexibility but also the ionic conductivity. The combination of impedance spectroscopy and four-probe DC measurements indicates that the GPC with x=13 vol% polymer exhibits the highest lithium ion conductivity, varying from 3×10^-4 Ω^-1 cm^-1 at room temperature to 1.4×10^-3 Ω ^-1 cm^-1 at 80°C. The evolution of impedance spectra of the cells show that kinetic stability of the GPC electrolytes against Li_xC₆ and LiMn₂O₄ electrodes is reasonably good, although there is an initial increase in interfacial resistance during cycling