Friction-induced fabrication of flexible supercapacitive microelectrodes

With miniaturized electronic devices becoming increasingly pervasive, micro energy storage devices have attracted great attentions. Micro-supercapacitors have great potentials due to its long lifetime and high power densities. Here we demonstrate low-cost and lithography-free fabrication of flexible micro-supercapacitive electrodes over large areas by friction-induced nanofabrication of silicon nanostructures array and electrodeposition of MnO₂ nanostructures. The silicon nanostructures are fabricated by sliding a diamond tip on Si(100) surface under a given normal load combined with wet etching in potassium hydroxide (KOH) solution. Since the scratched pattern shows lower etching rate than that of non-scratched surface in KOH solution, such pattern can served as an etching mask to protect the silicon below from etching to some degree. Hence, the hillock silicon nanostructures can be realized on Si(100) surface. After reverse moulding, metal film sputtering and MnO₂ nanostructures integration, the flexible microelectrodes are fabricated and show good electrochemical performances. The proposed friction-induced fabrication method has potential in bio-implantable and wearable miniaturized devices. (paper)