High rate performance porous carbon prepared from coal for supercapacitors

• Porous carbon is prepared through two-step activation.
• The capacitance of porous carbon reaches to 258 F g−1 at a current density of 1 A g−1.
• Porous carbon exhibits 81% capacitance retention at a current density of 30 A g−1.

Porous carbon with high specific surface areas up to 1851 m2 g−1 was prepared from coal by chemical activation. The specific capacitance of the porous carbon reaches 258 F g−1 at a current density of 1 A g−1 with about 81% capacitance retention at a current density of 30 A g−1. The porous carbon exhibits good cycling durability with 92% specific capacitance retained at a current density of 2 A g−1 after 1000 cycles.