Multilayer-Dense Porous Carbon Nanosheets with High Volumetric Capacitance for Supercapacitors

Two-dimensional (2D) porous carbon materials with large specific surface area (SSA) and high packing density are promising candidates for supercapacitors but still a major challenge. Herein, a simple 2D space-confined method was proposed to fabricate multilayer-dense porous carbon nanosheets (MPCN) by taking advantage of the stacking effect from rapid-drying MgAl-layered double hydroxides (MgAl-LDH). It is found that the addition of MgAl-LDH plays a vital role in improving the sample yield and packing density of porous carbon materials, in comparison to that prepared by the traditional activation strategy. The obtained MPCN-800 sample demonstrates a large SSA of 2111 m2 g–1 with a high volumetric density of ca. 0.85 g cm–3, which enables outstanding gravimetric and volumetric specific capacitance of 374 F g–1 and 318 F cm–3, respectively, at a current density of 0.5 A g–1 as the electrode for supercapacitor. Furthermore, a symmetric two-electrode device was assembled with MPCN-800 sample for evaluating its practical application. It has a high charge-storage performance of 292 F g–1 and superior rate capability in aqueous electrolyte, meanwhile exhibiting a specific capacitance of 145 F g–1 under a voltage window of 2.5 V and a maximum energy density of 31.5 Wh kg–1 at an output power of 313 W kg–1 in organic electrolytes. The present work provides a novel and promising strategy to prepare porous carbon materials with high volumetric density for high-performance supercapacitors.