Influence of the configuration in planar interdigitated electrochemical micro-capacitors

We have investigated the influence of the geometric configuration of planar interdigitated micro-supercapacitors on their specific energy and specific power. The theoretical values of the Equivalent Series Resistance (ESR) were deduced from an analytical expression of the cell constant К, and compared with experimental Electrochemical Impedance Spectroscopy (EIS) measurements performed on gold current collectors with different interdigitated patterns (varying the interspace, width, length and number of interdigitated fingers). It is shown that the configuration plays a key-role on the electrochemical performances of the device, and that the specific power is enhanced by a reduction of the interspace.Based on these results, we have realized hydrous RuO2-based thin films electrochemical capacitors integrated on silicon with an optimized configuration, using conventional photolithography techniques and electrodeposition from an aqueous chloride solution. The micro-supercapacitor is characterized by a cell capacitance of 0.2 mF cm−2 per footprint area, and was able to cycle at a scan rate of 100 V s−1.

► The geometric configuration plays a key-role on the performances of μ-SCs. ► The reduction of the interspace enhances the specific energy and power. ► A high resolution μ-SC with interspace as low as 5 μm has been realized. ► The RuO2 based μ-SC was able to cycle up to 100 V s−1.