Novel Solanum torvum Fruit Biomass-Derived Hierarchical Porous Carbon Nanosphere as Excellent Electrode Material for Enhanced Symmetric Supercapacitor Performance

Biomass-based hierarchical porous carbon nanospheres offer an outstanding performance of electrode materials in electrochemical energy storage device applications. However, integrating all these advantages into one fabric is still a challenge. Therefore, this study aims to develop novel biomass of Solanum torvum fruit (STF) as a hierarchical porous carbon nanosphere source for high-quality electrode material for supercapacitor applications. The STF-based carbon nanospheres were synthesized with a green, sustainable strategy through ZnCl 2 impregnation, carbonization, and physical activation. Through the 0.5 M ZnCl 2 , it was discovered that the carbon nanosphere maintains a dense spherical structure with enriched 3D "cow tripe-like" hierarchical pores. The optimized carbon nanosphere yielded a high specific surface area of 1176.29 m 2 g −1 with a nearly balanced combination of the micro-mesopores. The combination of the 3D hierarchical pore structure and densely packed nanospheres gave high electrochemical properties of the symmetric supercapacitor with a delightful specific capacitance of 154 Fg −1 at 1 Ag −1 in the H 2 SO 4 electrolyte and high cyclic performance with coulombic efficiency ~ 84.5%. The energy density was boosted to 30.4 Whkg −1 in power density of 1.27 kWkg −1 5 Ag −1 . Therefore, porous carbon nanospheres from novel STF biomass are ideal candidates as electrode materials for high-performance electrochemical energy storage devices.