High-performance supercapacitors based on self-supporting thick carbon electrodes from renewable biomass wood

It is expected that supercapacitors will be used for next generation emerging energy storage devices. The electrode is the most important component of supercapacitors, and thick carbon electrode is promising for supercapacitors, while maintaining a high specific capacitance and cycle life is still a fundamental challenge for thick electrodes. Herein, we reasonably designed a low cost, green, porous and high-quality loaded (40 mg cm−2) self-supporting thick carbon electrode (800 μm), and systematically studied effect of section pore structure on its electrochemical performance. The thick carbon electrode retained the natural pore structure of paulownia combined with mesopores and micropores formed by KOH etching, which increased the transport kinetics of electrolyte ions. The specific capacitance of the ultra-thick self-supported electrode reaches 7120.7 mF cm−2 (257.5 F g−1 and 89.1 F cm−3). The assemble symmetric supercapacitor (SSC) displayed a high-energy density of 2.55 mWh cm−3 at a power density of 3308 mW cm−3, and capacity retention rate of 87.75% atter 5000 cycles. The work provides a new ultra-thick electrode design strategy towards high performance energy storage devices.