Ion Injection by Metallic Electrodes in Highly Polar Liquids of Controlled Conductivity

It is shown that conduction in high electric fields (100 < E < 500 kV/cm) in propylene carbonate (Er=69) between metallic electrodes is due to the production of negative ions near the cathode. Taking into account the electrohydrodynamic effects, it is found that the influence of the acting parameters (electrode gap, resistivity, nature of the electrodes, and temperature) is in agreement with a model of electrochemical reaction in the compact layer. Based on our experiments, it is concluded that the width of the potential barrier is 1.5 nm and its absolute height 600 mV. At low fields (0.1 < E < 10 kV/cm), stationary currents occur as a result of electrochemical reactions near the electrodes and the presence of dissolved electrolytes. Transient currents correspond to the displacement of the positive diffuse layer from the anode to the cathode.