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

A novel monolithic carbon sponge is prepared by a ZnCl 2 -assisted carbonization of commercial melamine foam (MF) at 800 °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 ZnCl 2 activation plays an important role in improving the supercapacitive behavior of NOCSs. Compared with the NOCS without ZnCl 2 activation treatment, the optimal NOCS-1/10, obtained with a ZnCl 2 /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 10 000 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 .