Solder-reflow resistant solid-state micro-supercapacitors based on ionogels†
All-solid-state devices and thermal resistance to solder reflow are crucial issues with respect to micro-supercapacitors. While the latter issue can be addressed by using ionic liquids, the former shows promising results by employing the ionogel approach. The present study focuses on a novel formulation of ionogels—for use as solid state electrolytes in micro-supercapacitors with silicon nanowire electrodes—which promotes the crack-free formation of an efficient solid electrolyte onto silicon nanostructures in a single-step sol–gel process. The capacitance obtained was the same as that for a device using a non-confined ionic liquid, showing a good wetting of the 3D nanostructured silicon electrodes by the sol precursor of the solid ionogel. The assembled symmetric micro-supercapacitor exhibits very high cycling stability and can sustain the reflow soldering process used in the fabrication of microelectronic devices without compromising their electrochemical performance, and even improving their frequency response.