Partial electronic conductivity of nanocrystalline Na2O2

Abstract

Understanding charge carrier transport in Na2O2, being one of the possible storage materials in the non-aqueous Na-O2 battery, is key to the development of this type of energy storage system. The electronic and dynamic properties of Na2O2 are expected to greatly influence the overall performance and reversibility of the discharge process. Thus far experimental studies on this topic are rare. To measure the extremely low conductivities setups with sufficiently high sensitivity are needed. Here we studied the partial electronic conductivity σeon of nanocrystalline Na2O2 by potentiostatic polarization measurements which we carried out at room temperature. σeon turned out to be in the order of 8.8 × 10-14 S cm-1; with a very poor total conductivity of σtotal = 17 × 10-14 S cm-1 we obtained σtotal/σeon ≈ 2 clearly showing that ionic transport of Na ions is strongly coupled to electronic dynamics.