Coarsening-induced hierarchically interconnected porous carbon polyhedrons for stretchable ionogel-based supercapacitors

Carbonaceous materials have received extensive attention as electrode materials for electrochemical energy storage systems owing to their superior features, including light weight, high electrical conductivity and specific surface area (SSA), tunable pore structures, and desirable surface properties. For ultrahigh-energy-density supercapacitors (SCs), hierarchically interconnected micro-/meso‑/macroporous carbons (HICs) are desirable for both effective ion polarization and transport, especially when electrochemically stable but dynamically sluggish ionic liquids are employed as the electrolytes. Herein, we demonstrate coarsening-induced HIC polyhedrons with an ultrahigh SSA (3064 m² g⁻¹) from polymer-infiltrated metal-organic frameworks (MOFs). The HIC-based SCs exhibit an outstanding capacitance of 268.4 F g⁻¹ with an ultrahigh energy density of 149 Wh kg⁻¹, which are comparable to the best values reported to date, indicating that expedited ion-transport via hierarchically interconnected large meso‑/macropores affords maximum utilization of the micropores of the carbon electrodes. Furthermore, stretchable all-solid-state SCs operating at 120% strain with a very high areal capacitance of 33 mF cm⁻² and an energy density of 0.041 mWh cm⁻² are also demonstrated. These results provide a ubiquitous strategy for developing MOF-based hierarchically interconnected carbonaceous materials with ultrahigh SSA for high-performance SCs compatible with stretchable and wearable electronic devices.