Nitrogen-modified spherical porous carbon derived from aluminum-based metal-organic frameworks as activation-free materials for supercapacitors

Abstract

Carbon materials derived from metal-organic frameworks (MOFs) retain the precursor's regular unique morphology and net-like voids, which offers them the advantages of large specific surface area (SSA) and high capacitance for energy storage. In this paper, spherical amorphous porous carbon materials with hierarchical pores (DHTAC-2) were prepared using one-step carbonization of Al-MOF. The carbon has a large SSA (2666 m2 g−1) and a large pore volume (2.35 cm3 g−1). The obtained carbon (DHTAC-2) demonstrates an excellent specific capacitance (298.8 F g−1) at 1 A g−1 and capacitance retentions of 97.3 % and 98.0 % after 120,000 cycles at 50 A g−1 and 100 A g−1, respectively. In addition, Nitrogen-doped carbon (N-DHTAC) has increased pyridine-N, pyrrole-N and graphite-N content. The three types of N significantly improved its wettability, reversible pseudocapacitance and conductivity, respectively, resulting in a superior capacitance (355.0 F g−1@1 A g−1) and enhanced energy density (17.7 Wh kg−1@350 W kg−1) of the assembled electric double layer capacitor (EDLC) device. The device exhibits an extremely low decline rate of 10.12 % over 10,000 cycles at 10 A g−1, verifying N-DHTAC material is a promising active material for supercapacitors.