Cucurbit[6]uril-Derived Sub-4 nm Pores-Dominated Hierarchical Porous Carbon for Supercapacitors: Operating Voltage Expansion and Pore Size Matching

The intrinsic properties of carbon-based material and the voltage window of electrolyte are the two key barriers to restrict the energy density of carbon-based supercapacitors (SCs). Herein, a cucurbit[6]uril-derived nitrogen-doped hierarchical porous carbon (CBC x ) with unique pore structure characteristics is synthesized and successfully applied to construct SCs based on different electrolyte systems. Owing to narrow pore size distribution (0.5–4 nm), colossal ion-accessible pore volume, prominent supermesopore volume, and reasonable heteroatom configuration, the CBC x -based SCs demonstrate excellent electrochemical performances with high operating voltages in two distinct systems. The optimal SCs can output a maximum energy/power density of 18 Wh kg −1 (11.1 Wh L −1 )/20 kW kg −1 (12.3 kW L −1 ) with an operating voltage of 1.2 V in potassium hydroxide aqueous electrolyte, as well as an ultralong cycle life of up to 50 000 cycles (0.046% decay per 100 cycles). Furthermore, the optimal SCs deliver an exceptionally high energy/power density of 95 Wh kg −1 (58.4 Wh L −1 )/70 kW kg −1 (43 kW L −1 ) with an ultrahigh operating voltage of 3.5 V in 1-ethyl-3-methylimidazolium tetrafluoroborate electrolyte. This work opens up a new application field for cucurbit[6]uril and provides an alternative avenue for optimizing the performances of carbon-based materials for SCs.