Liquid nitrogen-controlled direct pyrolysis/KOH activation mediated micro-mesoporous carbon synthesis from castor shell for enhanced performance of supercapacitor electrode

Direct pyrolysis/KOH activation of carbon from castor shell biomass is an economical combination of two processes to breakdown biomass lignin effectively. The advanced liquid nitrogen-controlled direct pyrolysis/KOH activation technique is even a shortened process, which optimizes the fugacious bond reformation for enhancing supercapacitors' performance. Novel quenching of the red-hot activated carbon (heated at 800 degrees C) in liquid nitrogen is peculiar to the demonstrated structural changes. The desired throughput designated nKAC exhibited a high specific surface area of 1468 m(2) g(-1) over the initial 1131 m(2) g(-1) for KAC. In 6 M KOH electrolyte, the nKAC electrode exhibited a high specific capacitance of 481 F g(-1) at 1 A g(-1) and an excellent rate capability of 298 F g(-1) at 30 A g(-1). In symmetric two electrodes test, the electrodes of nKAC show a high energy density of 17.75 Wh kg(-1) at 0.5 A g(-1) in 1 M Na2SO4 electrolyte compared with 14.75 Wh kg(-1) of KAC electrodes. Furthermore, the nKAC still maintained a high energy density of 12.4 Wh kg(-1) at 5.0 A g(-1) corresponding to a high power density of 4500 W kg(-1). This simple and green method has potential applications in the synthesis of porous carbon based on waste biomass for enhancing performance of electrode materials.