Silica-assisted bottom-up synthesis of graphene-like high surface area carbon for highly efficient ultracapacitor and Li-ion hybrid capacitor applications

Abstract

We report a facile bottom-up approach for the synthesis of pure and macro-sized (>500 nm) graphene-like carbon by precisely employing sp² carbon rich 1,2,4,5-benzene tetracarboxylic acid (BTCA) as a precursor. We also addressed the features, such as high specific surface area (SSA) and sp² hybridized carbon content, of the BTCA-derived carbon (BTCADC) over conventional top-down processed reduced graphene oxide (RGO). For instance, a two fold enhancement in SSA (960 m² g⁻¹) and C : O atomic ratio (∼19) was noted for BTCADC when compared to RGO (SSA: 402 m² g⁻¹ and C : O ratio ∼ 10). The SSA of BTCADC was further extended to 2673 m² g⁻¹via a chemical activation process (A-BTCADC) along with a high pore volume (2.15 cm³ g⁻¹). Furthermore, we attempted to explain the unsolved issue of carbon layer stacking (π–π stacking) in RGO by precisely adopting a bottom-up approach. From an application point of view, we explored the possibility of using such carbonaceous materials as promising electrodes for both symmetric and Li-ion hybrid supercapacitor configurations in an organic medium. The A-BTCADC based symmetric cell in a 1 M tetraethylammonium tetrafluoroborate (TEA·BF₄) in acetonitrile (ACN) electrolyte displayed a specific capacitance (C_sp) of 225 F g⁻¹ (at 0.5 A g⁻¹) with a stable cycling profile of up to 10 000 cycles (at 10 A g⁻¹) between 0 and 3 V. This bottom-up approach opens new avenues to extend graphene-based science and technology to the next level.