Dodecahedral carbon with hierarchical porous channels and bi-heteroatom modulated interface for high-performance symmetric supercapacitors

Abstract

Hierarchical porous channels and a well-modulated interface are two main parameters for electrode materials that can promote their energy storage performance by accelerating the electrolyte diffusion and realizing their strong coupling with electrolyte ions. Inspired by the COMSOL Multiphysics simulations and density functional theory calculations, we design B, N dual-doped, hierarchical porous carbon (BN-HPC) by pyrolyzing hierarchical porous zeolitic imidazolate framework-8 with boric acid. The resulted BN-HPC electrode achieves a high specific capacitance of 236.9 F g−1 at a current density of 1 A g−1 in 1 M H2SO4 electrolyte, which is further assembled into the BN-HPC//BN-HPC symmetric supercapacitor with a high energy density of 33.3 Wh kg−1 at a power density of 212.5 W kg−1. The excellent energy storage performance of the BN-HPC electrode is attributed to its hierarchical porous structure and bi-heteroatom (N and B) doped carbon surface with a low binding energy value of −2.77 eV. This work provides a general and fresh insight into the design of dodecahedral carbon by combining hierarchical porous structure and bi-heteroatom doping strategy that can be used for not only aqueous supercapacitors but also other energy storage devices.