Nitrogen/oxygen co-doped monolithic carbon electrodes derived from melamine foam for high-performance supercapacitors

A novel monolithic carbon sponge is prepared by a ZnCl2-assisted carbonization of commercial melamine foam (MF) at 800 degrees C in a N-2 atmosphere. The as-prepared nitrogen/oxygen co-doped carbon sponges (NOCSs) can be directly applied as monolithic electrodes for supercapacitors without using any additives. It is found that ZnCl2 activation plays an important role in improving the supercapacitive behavior of NOCSs. Compared with the NOCS without ZnCl2 activation treatment, the optimal NOCS-1/10, obtained with a ZnCl2/MF weight ratio of 1:10, has the best capacitive performance due to its unique porous architecture, rich pseudocapacitance-active species, and good electron/ion transfer feature. It exhibits a high specific capacitance (242 F g(-1) at a current density of 0.5 A g(-1) and 325 F g(-1) at a scan rate of 10 mV s(-1)) and good electrochemical cyclability (97% after 10000 cycles at 5.0 A g(-1)). When being further assembled into an all-solid-state supercapacitor (PVA/KOH electrolyte), it can deliver an energy density of 4.33 W h kg(-1) at a power density of 250 W kg(-1) and 3.13 W h kg(-1) at a power density of 3 kW kg(-1).