Exceptional electrochemical properties of coconut shell carbon-phenolic resin composite for supercapacitors

Carbonaceous materials appear to be optimally suited to supercapacitors (SCs). In order to achieve performance that transcends the limitations of a single material (primarily in terms of energy density and durability), promising carbon-based composites have been widely studied, yet their design often faces a challenge in balancing charge storage, ion transport, and electron conduction. This study addressed this issue by leveraging the abundant and cost-effective coconut shell carbon (CSC) and modified phenolic resin (PF) to create a composite precursor, CSCPF, without the need for additional auxiliary reagents. The resulting capacitor carbon material, CSCPF-850, exhibits remarkable electrochemical properties. Its unique porous structure, comprising a combination of micropores and graded mesopores, offers abundant ion storage sites and efficient ion transport channels, contributing to its exceptional electrochemical performance. In a 6 M KOH electrolyte, CSCPF-850 demonstrates a high specific capacitance of 383.14 F g⁻¹ at 0.5 A g⁻¹ and retains 265.67 F g⁻¹ at 30 A g⁻¹, showcasing its superior rate capability. Moreover, the symmetric coin cell assembled with CSCPF-850 exhibits remarkable cycling stability, retaining 101.78 % of its capacitance after 50,000 cycles at 10 A g⁻¹. In a KOH/PVA gel electrolyte, the solid-state device demonstrates an impressive energy density of 18.21 Wh kg⁻¹ at 404.67 W kg⁻¹, maintaining substantial energy density even at ultrahigh power densities.