Nitrogen-enriched compact biochar-based electrode materials for supercapacitors with ultrahigh volumetric performance

• Published in: Journal of power sources 2019-11, Vol.439, p.227067, Article 227067
• Main Authors: Zhang, Wu, Zou, Yubo, Yu, Chuying, Zhong, Wenbin
• Format: Article
• Language: English
• Subjects: Biochar-based; Biomass; Nitrogen-enriched; Supercapacitor; Volumetric performance
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2019.227067

Biochar produced by pyrolyzing biomass at relatively low temperature generally possesses poor conductivity and is rarely used in the field of energy-storage. Herein, a nitrogen-enriched compact biochar-based material with high conductivity is successfully prepared from sodium ligninsulfonate, graphene oxide and p-phenylenediamine through evaporation and low temperature pyrolysis. Sodium ligninsulfonate is used as biochar source, and graphene oxide is reduced to provide high conductivity. The product of p-phenylenediamine reacting with sodium ligninsulfonate and graphene oxide, and polymerized through evaporation and carbonization process forms compact char. As-prepared biochar possesses high nitrogen content (14.3 at.%), yield (69.5 wt%), density (1.98 g cm−3) and conductivity (~0.078 S m−1). The biochar single-electrode exhibits superior gravimetric specific capacitance (480 F g−1 at 1 A g−1), ultrahigh volumetric specific capacitance (950 F cm−3) and good cycle stability in 1 M H2SO4 electrolyte. Particularly, assembled symmetric supercapacitor delivers outstanding gravimetric and volumetric energy density (13.4 W h kg−1 and 26.5 W h L−1, respectively) in 1 M H2SO4 electrolyte, and even better performance in 1 M Na2SO4 electrolyte (21.6 W h kg−1 and 42.8 W h L−1, respectively). This novel strategy provides a promising approach to prepare biochar-based materials as high performance supercapacitor electrodes in the applications of sustainable energy-storage devices. [Display omitted] •NB-GLP with high conductivity is prepared from Lig, GO and PPD.•NB-GLP possesses high N content (14.3 at.%) and density (1.98 g cm−3).•NB-GLP single-electrode exhibits ultrahigh volumetric capacitance of 950 F cm−3.•NB-GLP assembled supercapacitor shows high volumetric energy density (42.8 W h L−1).