The mixed-phase composite electrolytes have been widely studied. The conductivity enhancement mechanism, which assumes amorphisation of the polymer matrix at the polymer-filler interface, is widely accepted. The contrary effect of the matrix stiffening and thus the decrease of conductivity was observed for a higher concentration of a wide range of inorganic fillers. Finally, the maximum conductivity is observed for 10-20 wt.% of the additive. In this work, a system containing small grains of metallic aluminum is investigated by the means of XRD, DSC, EIS, SEM and FT-IR. Contrary to previous studies, the present system shows maximum conductivity for a much smaller amount of added grains (1-2 wt.%). The highest ambient temperature conductivity value is higher than 5 X 10(-6) S cm(-1). The observed conductivity is of purely ionic character. The Almond-West Formalism was used to study the mechanism of conductivity in this system.