Preparation of microwave-assisted expired honey derived electrodes with excellent performance for supercapacitors

Abstract

Microwave and hydrothermal method were employed to prepare expired honey-based biochar respectively, followed by KOH activation, carbonization and Co 2+ catalysis. The effect of microwave heating and the mechanism of Co 2+ catalysis are investigated by XRD, Raman, XPS and BET results. The biochar heated by microwave technology has interconnected pores, higher specific surface area (1404.6 m 2 g -1 ), macropore volume (1.081 m 3 g -1 ), oxygen-rich atoms (9.71 at.%), and highly graphitized structural characteristics, compared with that of hydrothermal method with lower specific surface area (451.2 m 2 g -1 ) and oxygen atom content (8.71 at.%). Due to its dominant structural characteristics, supercapacitors (SCs) based asprepared expired honey biochar (CMC) exhibit superior capacitive performance, including ultra-high capacitance (up to 758 F g -1 at current density of 0.2 A g -1 ) and good cyclic stability (over 96.7% capacitance retention at 10.0 A g -1 after 10 000 cycles of constant current charge and discharge) in a three-electrode system of 2.0 M H2SO4 electrolyte solution. The excellent electrochemical properties and efficient synthesis of biomass-derived carbon materials provide an economical and feasible strategy for large-scale production of high-performance electrodes.