Nitrogen-doped two-dimensional porous carbon sheets derived from clover biomass for high performance supercapacitors

5 years ago

Nitrogen-doped two-dimensional porous carbon sheets derived from clover biomass for high performance supercapacitors

Highly porous carbon sheets were prepared from fresh clover stems under air atmosphere via a facile potassium chloride salt-sealing technique, which not only avoids using the high cost inert gas protection but also spontaneously introduce multi-level porosity into the carbon structure taking advantage of the trace of oxygen in the molten salt system. The as-obtained porous carbon sheets possess high specific surface area of 2244 m² g⁻¹ and interconnected hierarchical pore structures from micro-to macro-scale, which provide abundant storage active sites and fast ion diffusion channels. In addition, the spontaneously formed N (2.55 at%) and O (6.94 at%) doping sites not only improve the electron conductivity of the electrode but also enhance the specific capacitance by introducing pseudocapacitance. When employed as supercapacitor electrodes, a high specific capacitance of 436 F g⁻¹ at 1 A g⁻¹ and an excellent rate capacity with capacitance remaining 290 F g⁻¹ at 50 A g⁻¹ are demonstrated. Furthermore, the assembled symmetric supercapacitor delivers a high specific capacitance of 420 F g⁻¹ at 0.5 A g⁻¹, excellent energy density of 58.4 Wh kg⁻¹ and good cycling stability which retains 99.4% of the initial capacitance at 5 A g⁻¹ after 30,000 cycles.

Publisher URL: www.sciencedirect.com/science

DOI: S0378775317310042