Honeycomb-Like Carbon with Tunable Pore Size from Biomass Phoenix Dactylifera Midrib for Highly Compressible Binder-Free Supercapacitors

Developing high-performance supercapacitors with low-cost, high-energy density and high-power electrode material is highly desirable and remains a major challenge. In this study, an electrode material with a honeycomb structure was prepared using Phoenix dactylifera or date midrib (DM) biomass as a precursor through the activation process of KOH and CO 2 . Its pore structure can be adjusted by varying the temperature of CO 2 activation at 700°C, 800°C and 900°C. The resulting electrode has a unique and efficient pore structure and regulation and has great potential for supercapacitor applications. The DM-800 electrode (temperature of CO 2 activation at 800°C) shows a highest specific capacitance of 227.84 Fg −1 at a current density of 1 A g −1 , and it has a carbon purity with a high atomic percentage of 90.16%. A supercapacitor cell is also designed similar with a sandwich on a symmetrical two-electrode system in a 1 M H 2 SO 4 atmosphere producing specific energy of 10.42 Wh kg −1 at a specific power of 133.33 W kg −1 . Therefore, this method can produce carbon electrodes with honeycomb-like structures and engineered pores for high-performance energy storage and conversion.