Electrochemical Functionalization of Porous Carbon for Aqueous Supercapacitors

In the context of the energy transition, the rapid deployment of renewable energy sources such as solar and wind power has created an increasing demand for efficient energy storage systems. Electrical double-layer capacitors (EDLCs) are particularly attractive owing to their high power density, excellent cycling stability, and fast charge/discharge capability. However, their energy density remains significantly lower than that of batteries, especially when aqueous electrolytes are employed. This limitation mainly arises from the narrow electrochemical stability window imposed by parasitic reactions, including water oxidation and reduction as well as carbon oxidation. The main objective of this PhD work is to develop an electrochemical functionalization strategy for self-supported carbon electrodes in order to enlarge the electrochemical stability window of aqueous supercapacitors while preserving their capacitive properties, thereby increasing the energy density of the device. This research was carried out within the HIPOHYBAT project of the French PEPR Batteries program, which aims to develop high-power energy storage technologies as sustainable alternatives to lead-acid and lithium-ion batteries.