An environmentally friendly strategy to prepare nitrogen-rich hierarchical porous carbon for high-performance supercapacitors.

A green route modulated by the addition of CaCl2 during the potassium compound-assisted synthesis is developed for the first time for the synthesis of nitrogen-rich hierarchical porous carbon (NRHPC) with high external surface area and moderate total pore volume. The NRHPCN constructed by nanosheets is capable of simultaneously achieving high gravitational and volumetric capacity for supercapacitors (SCs).