New Chemistry for New Material: Highly Dense Mesoporous Carbon Electrode for Supercapacitors with High Areal Capacitance

The discovery of new chemical reactions plays an important role in new material synthesis. For electric double-layer capacitors, a high packing density and a large surface area are required, but contradiction for current porous carbon electrodes. This causes a critical trade-off issue among gravimetric, areal, and volumetric capacitances. Herein, a new chemistry was found to synthesize a new type of carbon material, namely, a new reaction between CO and Li directly produces three-dimensional dense mesoporous carbon (DMPC). Its high packing density of 1.94 g/cm3 is much larger than those (0.05–0.7 g/cm3) of other porous carbon materials. Consequently, the aqueous electric double-layer capacitors with DMPC electrodes, which have 11.5 mg/cm2 mass loading, can reach high areal capacitance (2.15 F/cm2 at 1 A/g). It also exhibited large volumetric and gravimetric capacitances (220.5 F/cm3 and 205.2 F/g) without sacrificing areal capacitance. Furthermore, after 5000 charge/discharge cycles, capacitance retention is as large as 98.4%, indicating a high stability of the electrode. Therefore, DMPC is an excellent material for the electrodes of practical electric double-layer capacitors.