Highly porous, hierarchical microglobules of Co3O4 embedded N-doped carbon matrix for high performance asymmetric supercapacitors

Facile Co3O4 anchored nitrogen doped graphitic carbon (NGC) microsphere electrodes were synthesized and showed improved electrochemical capacitive performance. [Display omitted] •Cost-effective Co3O4 @ NGC microglobule electrodes were prepared.•It exhibited 3D-microglobules combined with a cauliflower nanostructure.•The Co3O4 @ NGC offered the highest electrochemical capacitance of 128.43 F.g−1.•An excellent life-time stability of 92.1% over 5000 cycles was observed. Nitrogen functionalized graphitic carbon (NGC), aside from being a distinctive support material for catalyst integration, is also intrinsically active for various electrochemical reactions especially in energy storage and conversion devices. Given the admirable conductivity and graded pore structure, the strategy of hybridizing metal oxides with NGC skeleton is reckoned to be highly compelling in the design of electrode materials. In this work, carboxy methylcellulose and melamine derived – Co3O4 NGC is used as an active electrode material for high performance asymmetric supercapacitors (ASC). The synthesized Co3O4 NGC exhibits microglobules with mesoporous network and maximum surface area of 445.3 m2 g−1 at 77 K. A solid state ASC is fabricated with activated carbon and Co3O4 NGC microglobules as negative and positive electrodes, respectively based on charge balancing theory, delivering ultra-high capacitance (128.43 F. g−1), energy density (45.66 Wh.kg−1) and power density (399.9 W.kg−1). Further, excellent capacitance retention (92.1%) over 5000 cycles confirms their long-term stability, which in turn enlightening the energy storage device progress for future generation electronics.