Fabrication of manganese dioxide nanoplates anchoring on biomass-derived cross-linked carbon nanosheets for high-performance asymmetric supercapacitors

• The CCNs was derived from a common biomass of Willow catkin.
• The MnO2@CCNs composite shows good capacitive performance.
• The assembled asymmetric cell shows high energy density.

In this paper, MnO2 nanoplates loading on biomass-derived cross-linked carbon nanosheets have been prepared by a two-step synthesis. At first, the cross-linked carbon nanosheets derived from willow catkin are synthesized by one-step pyrolysis and activation method, then the MnO2 anchored cross-linked carbon nanosheets is prepared via in-situ hydrothermal deposition. The asymmetric supercapacitor with terrific energy and power density is assembled by employing the MnO2 anchored cross-linked carbon nanosheets as the positive electrode and the cross-linked carbon nanosheets as the negative electrode in a 1 M Na2SO4 electrolyte. The asymmetric supercapacitor displays a high energy density of 23.6 Wh kg−1 at a power density of 188.8 W kg−1 within a wide voltage rage of 0–1.9 V. In addition, the asymmetric supercapacitor exhibits excellent cycling stability with only 1.4% capacitance loss after 10000 cycles at 1 A g−1. These discoveries open up the prospect of biomass/biowaste derived carbon-based composites for high-voltage asymmetric supercapacitors with superb energy and power density performance.