Biowaste derived porous carbon sponge for high performance supercapacitors
By Zhang, Wenbin; Liu, Bei; Yang, Mei; Liu, Yijiang; Li, Huaming; Liu, Pingle
Published in Journal of Materials Science & Technology
2021
Abstract
Here, an agricultural waste (the stem pith of helianthus annuus, SPHA) is firstly used as the precursor for preparing three-dimensional (3D) porous carbon sponge (PCS). The as-prepared 3D PCS (SPHA-700) possesses unique sponge-like structure, large specific surface area (SSA) and high nitrogen doping level (4.52 at.%), which benefit the enhancement of conductivity (5.8 S cm−1) and wettability. As a binder-free electrode for solid-state symmetric supercapacitor, SPHA-700 delivers a relatively high specific capacitance of 137.1 F g−1 at 0.5 A g−1. Moreover, activated SPHA-700 (SPHA-ac-700–2) displays an even higher specific capacitance (403.6 F g−1 at 0.5 A g−1) in 6.0 M KOH electrolyte. The SPHA-ac-700–2-based symmetrical supercapacitor can offer high specific capacitance (271 F g−1 at 1 A g−1) and good rate capability (82.1% of capacitance retention at 1–80 A g−1) in 6.0 M KOH electrolyte, together with high energy density (23.3 Wh kg−1 at 450 W kg−1) in 1.0 M Na2SO4 electrolyte. Such excellent performance of SPHA-ac-700–2 is believed to have originated from the crushed sponge-like structure, O/N-co-doping (10.6 at.% O and 3.3 at.% N), high SSA, large total pore volume, and hierarchical pore structure.