Abstract
The fabrication of high‐performance on‐chip 3D micro‐supercapacitors (MSCs) based on MnO2 pseudocapacitive binder‐free thin film electrodes (<500 nm thick) with interdigitated topology is reported. An original technological process easily scalable to pilot production line is proposed on 3 in. silicon wafers. High areal energy (>10 µW h cm−2) and power densities (>10 mW cm−2) are reached on small footprint micro‐supercapacitors (4 mm2) tested in aqueous electrolyte (0.8 V). Furthermore, the cell voltage of such MSCs can be increased up to 1.5 V with 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquids but at the expense of the areal capacitance. The performance in ionic liquid is in the same order of magnitude than the one obtained for aqueous electrolyte. The benefit from the 3D topology is clearly demonstrated when the surface performance is normalized to the electrode thickness allowing this study to obtain an interesting energy versus power tradeoff (>10 µW h cm−2 µm−1 and >1 mw cm−2 µm−1). This study aims at improving the energy density of MSCs while keeping high power capability, by combining the use of ionic liquids and the deposition of MnO2 thin film onto robust and efficient 3D scaffolds.