N-Doped celery-based biomass carbon with tunable Co3O4 loading for enhanced-performance of solid-state supercapacitors

Abstract

Celery biomass carbon supercapacitor electrodes with tunable Co₃O₄ loading are designed through an oxidation-precipitation and crystallization process of Co ions. The Co₃O₄ particles are uniformly decorated on the surface of the sheet-like celery carbon. The secondary large particles tend to be agglomerated with the increase of Co₃O₄ loading and the specific surface area decreases. Among the celery carbon and celery/100%Co₃O₄, celery/150%Co₃O₄, celery/200%Co₃O₄, celery/250%Co₃O₄, and celery/300%Co₃O₄ composites, the celery/150%Co₃O₄ composite provides the best specific capacitance of 853 F g⁻¹ at a current density of 1 A g⁻¹, and it maintains 80.1% of the initial specific capacitance after 3000 cycles. The energy density for the hybrid device reaches 11.8 W h kg⁻¹ at a power density of 375 Ws kg⁻¹. The N-doping shows an important impact on the specific capacitance of the composites. This study provides guidance for designing biomass carbon-based electrode materials.