Effect of various ammonium salts as activating additive on the capacitance performance of hierarchical porous carbon derived from camellia husk

摘要

Activator is crucial for the preparation of biomass-derived hierarchical porous carbons (BHPCs) because the activator mainly determines their pore structures and active sites. Herein, we propose to use camellia husk as a precursor to prepare BHPCs by a hydrothermal carbonization and ammonium salts including (NH4)(3)PO4, NH4Cl, (NH4)2SO(4), NH4HCO3, etc. assisted KOH activation. The prepared BHPCs showed a hierarchical porous structures containing micro-, meso-and macropores as well as a large specific surface area of 1874.6 m(2 )g(-1). Among additional ammonium salts, the (NH4)(3)PO4 and NH4Cl showed positive effects, NH4HCO3 exhibited almost no effect, but (NH4)(2)SO4 released negative effect on the capacitance performance of as-prepared BHPCs. The (NH4)(3)PO4 assisted KOH activated BHPC (BHPC-AP) delivered a higher specific capacitance of 253.7 F g(-1 )at 1 A g(-1) than other BHPCs in 6 M KOH. At the current density of 50 A g(-1), the specific capacitance of BHPC-AP remained 225.6 F g(-1 )with a high capacitance retention of 88.9%. The symmetric supercapacitors assembled by BHPC-AP (BHPC-AP SSC) released a high energy density of 12.11 Wh kg(- 1 )with power density of 250 W kg( -1). Furthermore, the BHPC-AP SSC exhibited a high cycling stability with 94.4% capacitance retention after 20,000 cycles at 5 A g(-1). The results indicate that the (NH4)(3)PO4 assisted KOH activation may be an effective approach to prepare porous carbons as electrode materials for high-performance supercapacitors.

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