A porous carbon-based composite PPC@co-NCNT derived from pomelo Peel as a flexible self-supporting electrode for supercapacitors

In this work, a porous carbon-based composite derived from pomelo peel with N doped carbon nanotubes on its surface (PPC@Co-NCNT) is prepared. After Polyvinyl alcohol (PVA) gel treatment, a flexible and self-supporting carbon material can be obtained. The prepared PPC@Co-NCNT material delivers a high specific capacitance of 1260 mF cm−2 in a three-electrode system without any current collector. After 10,000 cycles, the cycling retention rate still remains at 86.2 % under the current density of 10 A cm−2. A flexible solid asymmetric supercapacitor (ASC) is successfully assembled with the obtained carbon-based material PPC@Co-NCNT as the negative electrode, the PPC@Co-NCNT/MnO2 as the positive electrode, and the PVA/Na2SO4 gel as the electrolyte, respectively. The optimized ASC achieves an operating voltage of 1.8 V and displays a specific capacitance of 521.2 mF cm−2. The power density is 13.26 mW cm−3 at the energy density of 2.36 mWh cm−3. This work provides a new strategy of solid waste recycling and self-supporting electrodes design for the research of flexible energy storage supercapacitors.