Hierarchical porous carbon induced by inherent structure of eggplant as sustainable electrode material for high performance supercapacitor

The conversion and utilization of renewable biomass have attracted worldwide focus on sustainable development research. The study of biochar as electrode material for supercapacitors shows that the hierarchical porous structure of biochar directly affects the performance of supercapacitors. Here, we utilize the instinct porous structure of eggplant to establish the carbon material with hierarchical porous structure by simple carbonization process. The resultant eggplant-derived hierarchical porous carbon (EHPC) materials possess high specific surface area (1947 m2 g−1), high graphitization degree, and low resistance, which brings good rate performance, excellent specific capacitance (469 F g−1 at 1 A g−1), high energy density at high power density (38.51 Wh kg−1 at 687.1 W kg−1 in organic system and 15.83 Wh kg−1 at 55.5 W kg−1 in aqueous system), great capacitance retention (90% at a high scan rate of 100 mV s−1), and long lifetime (99.95% after 20,000 cycles). The performance tests of the capacitors assembled by EHPC materials show that porous biomass offer huge advantages in the preparation of hierarchical porous carbon materials for supercapacitors electrode materials.