A facile dual-functional hydrothermal-assisted synthesis strategy of hierarchical porous carbon for enhanced supercapacitor performance

Porous biomass-derived carbonaceous materials with low cost and sustainable sources were considered as attractive electrode materials for energy storage devices. However, how to achieve the effective activation for the built-up of hierarchical porous structure still remains challenging. Herein, a facile and effective activation strategy combining hydrothermal pre-treatment using acid/hydrogen peroxide as dual-functional modifier and KOH activation is proposed to prepare the interconnected macroporous carbon framework with high microporosity and small dimensional mesopores from Typha grass fluff (TGF). Acetic acid was used to exfoliate nanosheets from bulk of TGF and hydrogen peroxide introduced mesopores to the carbon skeleton. The as-prepared sample achieved a high capacitance value of 440 F/g at a current density of 0.2 A/g and long cycling life with capacity retention of 93.58% after 10,000 cycles, along with the high energy density of 36.67 Wh/Kg delivered at the power density of 300 W/Kg. The surface capacitive contribution of AA/HP-TGC-PH-600 is 61.14% at the scan rate of 2 mV/s and increase to 85.39% at the scan rate of 80 mV/s. A Bode frequency of 0.277 Hz at the angle of −45° was obtained, leading to a high response time of 3.61 s. This work proposed some new insights into the pore structure engineering of biomass derived carbon and an effective approach for the improvement of their energy conversion/storage performances.