Boosting the capacitive storage performance of MOF-derived carbon frameworks via structural modulation for supercapacitors

Abstract

Reasonable options about carbon-based electrode materials and electrolyte play crucial roles in the pursuant path of high-performance supercapacitors. Herein, the synthesis of hierarchical porous honeycomb-like carbon frameworks (HHCF) is reported, which was prepared through pyrolysis of metal-organic framework composite and subsequent activation process. HHCF with a high surface area and hierarchical meso-/micropores, can provide more adsorption sites and facilitate the fast ion transport. The HHCF electrode delivers a high specific capacitance of 361 F g−1 at a current density of 1 A g−1 in aqueous electrolyte and retains 182 F g−1 at 100 A g−1. Furthermore, the symmetric supercapacitors fabricated in 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4) electrolyte exhibits great specific capacitance of 174 F g−1 at 1 A g−1 and delivers excellent energy density of 74 Wh kg−1 at a power density of 872 W kg−1. More importantly, the flexible solid-state supercapacitor device assembled by HHCF electrodes and EMIMBF4/PVDF-HEP polymer gel electrolyte also presents soaring energy density and excellent flexibility performance. Our work may provide new insight in the design of MOF-derived carbon-based supercapacitor with high energy/power density.