Synthesis of hollow hierarchical porous carbon spheres from lignin by soft template and hydrothermal method for supercapacitors.

Among the various carbon-based electrode materials, porous carbon spheres stand out for their exceptional properties, such as high specific surface area (SSA), high percussion density, and distinctive surface chemistry, which are conducive to uniform surface modification and acceleration of electrolyte diffusion, thereby enhancing the energy density of battery. Hollow carbon spheres, with their unique structure, are drawing increasing attention for their potential applications in energy storage devices. In this work, hollow hierarchical porous carbon spheres (HPCS) were synthesized by one-pot method using alkali lignin extracted from corn straw as carbon precursor, CTAB as template agent, Zn2+ as crosslinking agent and KHCO3 as activator. HPCS-900 had a high SSA of 1959 m2 g-1 and pore volume of 1.21 cm3 g-1, and a specific capacitance of 293 F g-1 (0.2 A g-1) with a capacitance retention of 70.8 % (40 A g-1) as electrode material. When used in supercapacitor (SC), HPCS-900 exhibited an energy density of 17.5 Wh kg-1 at 134.9 W kg-1 and a cyclic stability of 86.7 % after 10,000 cycles.