A multi-template carbonization approach to hierarchically nanoporous carbon for high-performance supercapacitors

We demonstrate a multi-template carbonization approach to produce nanoporous carbon, without any complicated activation process. The mass ratio of Mg citrate, zinc metal, and Zn(OAc)(2)center dot 2H(2)O as well as the carbonization temperature play decisive roles in determining the carbon pore structures. The electrochemical performances were investigated in a two-electrode system, using a mixture of 1-ethyl-3-methyl imidazolium tetrafluoroborate and acetonitrile as electrolyte. More importantly, the cell configuration was measured at different operation temperatures of 25/50/80 A degrees C. The carbon-7(#) sample that was obtained using Mg citrate, zinc metal, and Zn(OAc)(2)center dot 2H(2)O as starting materials (with a mass ratio between them of 1:1:1) at 800 A degrees C delivers the best electrochemical behavior mostly reflected in its large Brunauer-Emmett-Teller (BET) surface area of 1,776.3 m(2) g(-1), high pore volume of 3.82 cm(3) g(-1), and hierarchical pore size distribution. It can exhibit good cycling stabilities and large specific capacitances of 152.2, 243.5, and 279.4 F g(-1), respectively, at the operation temperatures of 25/50/80 A degrees C. The corresponding energy densities are as high as 47.5, 75.9, and 87.2 Wh kg(-1), respectively, in the case of power energy of 1.5 kW kg(-1). The operation temperatures of 25/50/80 A degrees C revealed in the present work can greatly broaden the supercapacitor application of nanoporous carbons under extreme circumstances.