High-rate supercapacitor based on 3D hierarchical N-doped porous carbon derived from sustainable spongy cornstalk pith

Abstract Carbon-based supercapacitors have been widely applicated in the energy storage fields due to superior physicochemical stability and large specific power. However, there is still an urgent need for improvement of specific energy which can be attributed to low mesoporosity, poor conductivity and narrow working voltage. This paper has introduced spongy and porous cornstalk pith aerogel as carbon precursor and one-step facile carbonation treat to prepare the 3D hierarchical N-doped porous carbon as supercapacitor electrode materials. The obtained cornstalk porous carbon exhibits high mesoporous volume ratio (90.7%) and large specific surface area of 2155 m2 g-1 to the benefit of fast electrolyte ions diffusion and forming large double layer interface. And the N doping of 3.96 at% from cornstalk pith biological component and NH3 enhance the electron conductivity, a certain amount of capacitive performance and surface wettability of carbon materials with electrolyte ions. The electrochemical measurements have demonstrated that the sample shows a high specific capacitance of 381 F g-1 at 0.2 A g-1 with prominent rate performance (82% retention at 80 A g-1) and 97.6% capacitance retention after 50,000 cycles. Furthermore, to extend working voltage using an organic electrolyte (MeEt3NBF4/acetonitrile solutions), the cornstalk porous carbon electrode presents high specific energy of 47.5 W h kg-1 (1.50 kW kg-1) and an ultra-large specific power of 113 kW kg-1 (36 W h kg-1).