Porous carbons have been extensively studied in supercapacitors. However, it remains a grand challenge for porous carbons to achieve a volumetric capacitance ( Cv) of over 200 F cm-3 because of the low intrinsic density and limited capacitance. Herein, we propose a pomegranate-like carbon microsphere (PCS) constructed by monodisperse, submicron, N-doped microporous carbon spheres for high-volumetric-capacitance supercapacitors. The assembly of submicron carbon spheres into pomegranate-like structures significantly reduces the required binder amount (2.0 wt %) for electrode preparation, diminishes the interparticle resistance, and most importantly, endows the PCS with a high packing density (0.75 g cm-3). Benefited from the high surface area (1477 m2 g-1), N-doping (3.0 wt %), and high packing density, the PCS demonstrates a high Cv (254 F cm-3), four times that of unassembled monodisperse carbon spheres. This work opens a new avenue to enhance the Cv of porous carbons without compromising the rate capability or cyclability.
Keywords: electrical double-layer capacitor; pomegranate-like structure; porous carbon; spray drying; volumetric capacitance.