Hydrothermal synthesis of a graphene-based composite enabling the fabrication of a current collector-free microsupercapacitor with improved energy storage performance

Herein, the development and the characterization of an all-solid-state symmetrical and current collector-free microsupercapacitor based on a new reduced graphene oxide-polydopamine (rGO-PDA) composite are reported. The rGO-PDA composite is synthesized by a facile, eco-friendly and scalable hydrothermal approach in the presence of dopamine which can not only contribute to the oxygen functional groups removal from graphene oxide but also polymerize onto the rGO sheets reducing their restacking and improving the wettability of the electrode. The optimized rGO-PDA composite material exhibits excellent capacitance and cycling stability as well as an improved rate capability compared to the pristine rGO in Na2SO4 solution. This performance enhancement can be linked to the higher transfer kinetic and lower transfer resistance values of the ions involved in the charge storage process of rGO-PDA, as determined by ac-electrogravimetry. Furthermore, an all-solid-state microsupercapacitor was prepared employing the optimized rGO-PDA composite as electrode material. Interdigitated electrodes were obtained thanks to a CO2 laser and a Na2SO4/PVA hydrogel was employed, no current collector was used. This device achieves a noteworthy energy density of 6.2 mWh & sdot; cm-3 at a power density of 0.22 W & sdot; cm-3. Moreover, it exhibits exceptional cycling stability, retaining 104 % of its initial capacity even after undergoing 10,000 cycles at 2 V & sdot; s-1. A new reduced graphene oxide-polydopamine (rGO-PDA) material was obtained by an hydrothermal treatment of an aqueous solution containing GO and dopamine. The optimised rGO-PDA composite reveals superior transfer ion kinetics at the electrode/electrolyte interface compared to pristine rGO, probed by advanced electrogravimetry. A current collector-free device composed of interdigitated rGO-PDA electrodes was tested using a Na2SO4/PVA hydrogel electrolyte. It achieves remarkable energy and power densities with exceptional cycle stability.image