Multi-Heteroatom-Doped Carbon Materials for Solid-State\nHybrid Supercapacitors with a Superhigh Cycling Performance

Abstract

For\nthe purpose of assembling high-performance\nsolid-state hybrid supercapacitors (HSCs) with superior cycling stability\nand energy density, biomass-derived multi-heteroatom-doped carbon\nmaterials were prepared in this work and utilized as negative electrodes\nfor the supercapacitors. The applied biomass in this study included\norange peel and egg white; besides, we also prepared Ag-doped egg\nwhite as a precursor through a denaturation reaction to synthesize\na Ag-nanoparticle-decorated carbon material; the consequently obtained\ncarbon materials were referred to as OC, EC, and Ag–EC, respectively.\nThe as-synthesized heteroatom-doped carbon materials displayed excellent\nelectrochemical performance. The specific capacitance retentions were\n101.7, 105.4, and 107.4% for OC, EC, and Ag–EC, respectively,\nafter 50 000 cycles. In addition, a core–shell structured\nC/N–CoO@CoO/NiO nanomaterial was also synthesized and used\nas the positive electrode, which exhibited a high cycling stability\nof 111.6% after cycling for 50 000 times. The three corresponding\nsolid-state hybrid supercapacitors (HSCs) possessed excellent energy\ndensities of 33.1, 30.1, and 35.6 Wh kg^–1 at about\n850.0 W kg^–1, respectively. After cycling for 50 000\ntimes, their specific capacitance retentions were 145.9, 139.2, and\n140.0%, respectively.