High yield conversion of biowaste coffee grounds into hierarchical porous carbon for superior capacitive energy storage.

ABSTRACT: Recently great efforts have been focused on converting biowastes into high-valued carbon materials. However, it is still a great challenge to achieve high carbon yield and controllable porous distribution in both industrial and academic research. Inspired by the multi-void structure of waste coffee grounds, herein we fabricated hierarchical porous carbon via the combination of catalytic carbonization and alkali activation. The catalytic carbonization process was applied to obtain well-defined mesoporous carbon with carbon yield as high as 42.5?wt%, and subsequent alkali activation process produced hierarchical porous carbon with ultrahigh specific surface area (3549 m2 g-1) and large meso-/macropores volume (1.64 cm3 g-1). In three-electrode system, the electrode exhibited a high capacitance of 440?F?g-1 at 0.5?A?g-1 in 6?M KOH aqueous electrolyte, superior to that of many reported biomass-derived porous carbons. In two-electrode system, its energy density reached to 101?Wh?kg-1 at the power density of 900?W?kg-1 in 1-Ethyl-3-Methylimidazolium Tetrafluoroborate (EMIMBF4). This work provided a cost-effective strategy to recycle biowastes into hierarchical porous carbon with high yield for high-performance energy storage application.

SUBMITTER: Liu X 

PROVIDER: S-EPMC7044333 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature