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

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.