Graphitic‐Based Solid‐State Supercapacitors: Enabling Redox Reaction by In Situ Electrochemical Treatment. Issue 7 (10th March 2020) - Amjadipour, Mojtaba
Abstract: The quest for supercapacitors that can hold both high energy and power density is of increasing significance as the need for green and reliable energy storage devices grows, for both large‐scale and integrated systems. While supercapacitors for integrated technologies require a solid‐state approach, gel‐based electrolytes are generally not as efficient as their aqueous counterparts. Here, we demonstrate a strategy to enhance the performance of quasi‐solid‐state supercapacitors made by graphitized silicon carbide on silicon electrodes and polyvinyl alcohol (PVA)+H2 SO4 gel electrolyte. The electrochemical characterization shows an increase of the specific capacitance of the cell up to 3‐fold resulting from a simple agent‐free, in situ, electrochemical treatment leading to functionalization of the graphitic electrodes. The functionalization of the electrodes simultaneously enables redox reactions, without adding any redox agent, and increases the double layer contribution to the overall capacitance. The strategy and insights offered by this work hold great promise for improving quasi‐solid‐state, miniaturized on‐chip energy storage systems, which are compatible with silicon electronics. Abstract : Enabling redox reaction without additives : A simple path is shown to enable stable redox reactions in supercapacitors with graphitic carbon electrodes and PVA−H2 SO4 gel electrolyte, without the addition of external agents. This method relies on the in situ hydrolysis of water molecules within the electrolyte, promoting the functionalization of the graphitic electrodes with oxygen functional groups. We show that the oxygen functionalization also improves the double‐layer contribution to the overall capacitance thanks to an improved electrolyte intercalation of the graphitic electrodes.