Boosting Supercapacitor Energy Storage Using Microporous Carbon Derived from an Octavinylsilsesquioxane and Fluorenone-Linked Porous Hybrid Polymer

Supercapacitors (SCs), with their exceptional properties, offer a promising solution to the ongoing energy crisis, addressing the growing demand for high-energy storage devices. Polymeric organic porous materials (POIPs) exhibit various sizes, precisely controlled porosities, lightweight nature, extensive surface areas, impressive intrinsic porosity, attractive surface chemistry, outstanding stability, and customizable structures and functionalities. These features collectively render POIPs as a cost-effective material for applications in energy storage. This study successfully synthesized an octavinylsilsesquioxane (OVS)-FO-POIP through a Heck coupling reaction between OVS and 2,7-dibromo-9H-fluoren-9-one (DBFO). Confirmation of the OVS-FO-POIP’s chemical structure was achieved using solid-state ¹³C and ²⁹Si NMR and Fourier transform infrared analyses. Subsequently, carbonization and KOH activation at 900 °C yielded a porous carbon material, denoted as OVS-FO-POIP-900. Microporous characteristics were evidenced by specific surface area (S_BET) values of 264 m² g^-1 for the OVS-FO-POIP and 387 m² g^-1 for OVS-FO-POIP-900 and their corresponding pore diameters of 1.90 and 1.59 nm, respectively. Notably, OVS-FO-POIP-900 demonstrated an improved particular specific capacitance of 776 F g^-1 compared to that of the OVS-FO-POIP (271 F g^-1) at a current density of 1 A g^-1, in addition to an exceptional capacitance retention of up to 79% after 6000 cycles. The heightened surface area enhances the probability of electrochemical reactions, thereby elevating capacitance levels. To delve deeper into electrochemical performance, symmetric devices were constructed for both the OVS-FO-POIP and the OVS-FO-POIP-900, exhibiting specific capacitances of 167 and 268 F g^-1, respectively. Remarkably, OVS-FO-POIP-900 demonstrated outstanding performance in these electrochemical assessments, suggesting its potential suitability for SC applications.