Formation of High Surface Area Hierarchical Porous Carbon Via a Novel Two Step Activation Process for Fast Supercapacitors

Produce of hierarchical porous carbon (HPC) materials that process hierarchical structure, high specific surface area and large pore volume is still a global challenge. Here we develop a novel sample two-step activation method, which introduces Ca(OH)(2) at the first step to produce the meso-macro porous structure and KOH at the second step to create micropores, to synthesize hierarchical porous carbon using tannin extract as processor. Benefited from this method, the synthesized HPC exhibits the specific surface area of 1996.9 cm(2) g(-1), pore volume of 1.09 cm(3) g(-1), and hierarchical porous structure with micro-meso-macro pores. The prepared HPC with well-developed mesopores and micropores can provides ideal channels for ion diffusion with low migration resistances, enabling an excellent power density and cycling stability for supercapacitors, and it exhibits the specific capacitance of 248 F g(-1) at 5 A g(-1) and maintained at 228 F g(-1) at 20 A g(-1). Tannin extract is cheap, easy to obtain and environmentally friendly, combined with the excellent electrochemical performances and the well-developed two-step method, provides a new idea for the preparation of HPC for high performance supercapacitor.