Self-Supported Flexible Electrodes on Carbon Backbone with Interconnected Tubular Structure for Supercapacitors Operating under Wide Temperature Range

Wide-temperature operation coupled with a high energy density remains a significant challenge for carbon-based supercapacitors (SCs). Herein, a novel porous carbon (NPHTCK) engineered with an interconnected tubular architecture and enriched microporosity is reported, demonstrating intrinsically high capacitance (302 F·g–1 at 1 A·g–1 in 6.0 M KOH). Notably, mechanically robust and self-supporting flexible membrane electrodes (SFMEs), developed from NPHTCK without conventional current collectors, enable ionic liquid-based supercapacitors (SCF-IL) exhibiting exceptional performance over the ultrawide −50 to 100 °C temperature range. Remarkably, SCF-IL exhibits superior cycling endurance (maintaining 80.2% at 100 °C and 92.2% at −50 °C capacitance) after 5000 cycles at 3 A·g–1 and outstanding volumetric energy densities (2.0 Wh·cm–3 at 100 °C in 4800 W·cm–3 and 3.8 Wh·cm–3 at −50 °C in 7600 W·cm–3). This unparalleled combination of wide-temperature tolerance, high energy and power metrics, and stability highlights the promise of the NPHTCK-SFME design.