We report a new kind of polyethlene oxide (PEO)-Li based composite polymer electrolyte containing active nanocomposite particles with ethylene carbonate (EC)/propylene carbonate (PC) plasticizers embedded in mesoporous ${\mathrm{S}\mathrm{i}\mathrm{O}}_2$ ($\mathrm{E}\mathrm{C}/\mathrm{P}\mathrm{C}\mathrm{\text{−}}{\mathrm{S}\mathrm{i}\mathrm{O}}_2$). A very large enhancement of the ionic conductivity was observed for the $\mathrm{P}\mathrm{E}\mathrm{O}\mathrm{\text{−}}\mathrm{L}\mathrm{i}/(\mathrm{E}\mathrm{C}/\mathrm{P}\mathrm{C}\mathrm{\text{−}}{\mathrm{S}\mathrm{i}\mathrm{O}}_2)$ electrolytes. This could be attributed mainly to conducting $\mathrm{E}\mathrm{C}/\mathrm{P}\mathrm{C}$ nanochannels in the active nanocomposite particles. This unique mechanism is absent in currently known nanocomposite polymer electrolytes with inert oxide nanoparticles. Both high ionic conductivity and excellent stability of such new nanocomposite polymer electrolytes potentially makes it one of the most promising electrolyte materials.

• Received 30 June 2003

DOI:https://doi.org/10.1103/PhysRevLett.91.266104