Green synthesis of capacitive carbon derived from Platanus catkins with high energy density
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Heteroatom-doped hierarchical porous carbon was prepared from platanus catkins using a facile binary carbonate co-pyrolysis strategy combined with hydrothermal pretreatment. The as-obtained HPC-Na2CO3/K2CO3 possesses an appropriate specific surface area of 345 m2 g−1 and an inherited tubular structure composed of interconnected micro- and mesopores (0.6-5 nm), together with a rich heteroatom doping of O and N. HPC-Na2CO3/K2CO3 exhibits superior specific capacitance of 301.8 F g−1 at 0.5 A g−1, a desirable rate retention of 78.2% from 0.5 to 10 A g−1, and good cycling stability with 99.2% of initial capacitance retention after 5000 cycles at 5 A g−1 in 6 M KOH aqueous electrolytes. A symmetrical HPC-Na2CO3/K2CO3 capacitor can deliver an excellent energy density of 33.4 Wh kg−1 at the power density of 0.2 kW kg−1. Compared with the classical KOH and ZnCl2 activation process, this technique, using Na2CO3/K2CO3 etching to prepare catkin-derived porous carbon, has the advantages of simplicity, more balanced micro/mesopore ratio, recyclability, and no pollutants.
This work was financially supported by the National Natural Science Foundation of China (Project No. 21406044), the Zhejiang Province Public Welfare Technology Application Research Project (Grant No. LGF19B060007), and Natural Science Foundation of Zhejiang Province (Grant No. LQ17B060006).