Using inorganic dynamic porogens for preparing high-surface-area capacitive carbons with tailored micropores

A high-performance capacitive carbon should simultaneously possess the characteristics of high surface area, high tap density, electrical conductivity and good wettability to electrolyte. However, these features are usually incompatible and difficult to integrate into one carbon material. Herein, we consider this challenge and report a new preparation method of capacitive carbons that can meet the abovementioned characteristics using an inorganic CuCl salt as a dynamic porogen and l -glutamic acid as a carbon precursor. When the amount of CuCl 2 was controlled for exact coordination of Cu 2+ with NH 2 − and COO − of l -glutamic acid, Cu 2+ was atomically dispersed by the formation of Cu–N and COO–Cu. Upon high-temperature pyrolysis, Cu 2+ was gradually reduced to Cu + ; meanwhile, the evaporation of CuCl at around 350 °C resulted in the formation of uniform ultramicropores. After further pyrolysis to 900 °C, the remaining copper species were reduced to Cu and then catalyzed the graphitization of the carbon product. When the amount of CuCl 2 exceeded theoretical coordinated proportions, the molten salt effect of the aggregation of CuCl occurred over 450 °C, resulting in the generation of supermicropores. Eventually, the obtained carbon showed an exceptionally high surface area of 2051 m 2 g −1 and 3.22 at% nitrogen content with tap density of 0.35 g cm −3 , which resulted in specific capacitance reaching 273 F g −1 at 0.5 A g −1 and charge transfer of 0.21 Ω with cycle life over 20 000 cycles as a supercapacitor electrode. Considering the recyclability of the used inorganic salt and after comparing with conventional surfactant templating, we conclude that our synthesis opens up a new energy-saving approach for preparing porous carbon with tailorable micropore sizes and high surface areas even at temperature as low as 350 °C.