Hierarchical porous carbon originated from the directing associated with activation as high-performance electrodes for supercapacitor and Li ion capacitor

Abstract

A template-directing methodology combined with post-activation methodology is developed to synthesize hierarchical porous carbon (HPC) with a unique nanocage-like morphology and exceptional structural integrity, utilizing light MgO nanocapsules as templates and coal pitch as precursor. The specific surface area and pore volume of HPC can be precisely adjusted by varying the mass ratio between the chemical activator and PC. This optimized pore structure significantly enhances the kinetics of electrolyte ion diffusion, which is a crucial point for the high-performance supercapacitors. The superior capacitive energy-storage behavior with respect to capacitance and rate capability (168 and 160 F g⁻¹ at 1 and 100 A g⁻¹) can be delivered by HPC electrode as compared to commercial activated carbon and pristine PC. The great compatibility to high gravimetric and areal capacitances (173 F g⁻¹ and 1391 mF cm⁻²) can still be achieved even at 8 mg cm⁻² for HPC electrode. Moreover, a full hybrid Li ion capacitor fabricated using HPC, delivers outstanding rate capability, excellent Ragone performance, and exceptional cyclability, establishing the potential of this material for advanced energy storage systems. The successful integration of template-directed synthesis with activation techniques presents a scalable approach to convert coal pitch into high-performance electrode materials.