Apparatus for Measurement of Protonic Conductivity of Powdered Materials as a Function of Temperature and Humidity

Abstract

Presented is an approach to measuring protonic conductivity of powdered samples. The features of this method are the utilization of porous sample holder, which allows for an easy control of the water activity in the sample, the use of spring-loaded contact electrodes, which prevents the loss of contact upon sample shrinking, as well as the implementation of four-electrode ac impedance measurements, which reduces the inaccuracy due to interfacial capacitance of the probes. We also report conductivities of a low equivalent weight version of Nafion in film and powder forms as functions of relative humidity. These data show that the conductivity of a powder is several times lower than the conductivity of a film, which is likely due to the porous nature and intergrain resistances in the powder.

Fast Protonic Conductivity in Crystalline Benzenehexasulfonic Acid

“…The conductivity of BHSA powder was measured in a wide range of temperatures and humidities using a porous 4-electrode cell described in Ref. [1] It is remarkable that, at a given humidity and temperature, the conductivity of crystalline BHSA is about the same (Fig. 2) as the conductivity of Nafion, which relies on proton transfer in liquid water retained in sulfonate-clad pores.…”