Microporous ruthenium oxide films for energy storage applications

Highly porous ruthenium oxide films were prepared using ruthenium ethoxide solution at low temperatures. The specific capacitance of the ruthenium oxide film electrode made with ruthenium ethoxide solution is much higher than that made using the traditional ruthenium chloride solution. It was found that amorphous ruthenium oxide films with high porosity could be formed at temperatures of 100-200 °C. At temperatures above 250 °C, crystalline ruthenium oxide films were formed. Electrochemical capacitors were made with ruthenium oxide film electrodes and were tested under constant current charging and discharging. The maximum specific capacitance of 593 F/g was obtained from the electrode prepared at 200 °C. The interfacial capacitance increased linearly with increasing film thickness. A value of interfacial capacitance as high as 4 F/cm² was obtained from the electrode prepared at 200 °C.