The ionic conductivity of a large number of electrolyte materials, such as LiI, AgCl, AgI and CuCl, is known to be enhanced by the addition of inert submicron particles, most often alumina. Typically the conductivity is enhanced by I to 3 orders of magnitude for composites containing 10 to 40 volume % particles. Several other researchers have attributed this effect to an enhanced carrier concentration in a space charge polarization layer surrounding the alumina particles. However, estimates of the magnitude of such a space charge layer indicate that this mechanism alone can not account for the large enhanced conductivities reported for several of the composites.