High field conduction in propylene carbonate

The study of high field conduction of an highly polar liquid, propylene carbonate (εr = 65) is bath of fundamental and practical interest. It is proved that fields up to 450 kV/cm applied with metallic electrodes to the liquid, deionized by electrodialysis, produce negative ion injection. Ions are produced at the liquid-metal interface by an electrochemical process which is probally the reduction of the liquid. The current density versus the applied field is described by a unique curve in the range of studied conductivities. This is in agreement with a previous model according to which the injected current is controlled by electrochemical kinetics. Electrohydrodynamic turbulent motions of the liquid have but a small influence on the calculated currents. Fast transient measurements of the currents following a voltage step show that the kinetics of the injection in our experimental conditions is a fast process. This gives promise for applications needing strong carrier injection, such as liquid electrostatic generators.