2D−3D hybrid hierarchical porous carbon with intrinsic and external defects for high energy density supercapacitors

Abstract

The construction of interconnected hierarchical pore and defects structures is beneficial to realize the rapid transfer of electrons, and appropriate heteroatom doping (external defects) can fully expose more active sites and adjust the local electronic structure to improve the electrochemical performance. Herein, a novel symbiotic folded 2D− 3D hybrid hierarchical porous carbon doped with intrinsic and external defects was prepared by using porous silica as a hard template, surfactant as a soft template and in situ doping. The unique structure provided a large specific surface area (Ssa), micromeso-macro hierarchical structure, rich active sites, and the characteristics of 2D and 3D porous carbon. The positron lifetime spectra showed that the specific structure possessed different types of defects. The optimal N, O codoped symbiotic 2D− 3D hybrid porous carbon (NCP) exists vacancy-size free volume defects and demonstrated remarkable electrochemical performance as a supercapacitor electrode material in different electrolytes. A specific capacity of 358 F g−1 and excellent rate capability were obtained in a 6 M KOH electrolyte. The voltage window of the device was stabilized at 1.5 V, and a high energy density of 27.9 Wh kg−1 @ 749.55 W kg−1 was obtained. The unique carbon-based material maintained a high specific capacity under wide voltage windows, which enhanced the energy density and provided a new design idea for carbon-based energy storage materials in the future.