Synergistic integration of three-dimensional architecture composed of two-dimensional nanostructure ternary metal oxide for high-performance hybrid supercapacitors

Constructing electroactive materials with hierarchically structured porous architecture is promising for developing various energy storage electrodes. In particular, the transition metal complexes with this archistructure are potential toward the fabrication of high-performance hybrid supercapacitors (HSCs) due to the rational design and its peculiar Faradic battery-type charge storage behavior. Herein, we report the hierarchically structured microflowers of ternary nickel cobalt molybdenum oxide (NCMO) assembled by ultrathin nanosheets via a hydrothermal process and the subsequent calcination. The interconnected open network and abundant void space of hierarchically structured flower-like NCMO are associated with improved electrochemical performance. Consequently, the obtained NCMO electrode achieves the larger specific capacitance (C_s) of 1696 F g⁻¹ at 1 A g⁻¹ than the nickel molybdenum oxide (NMO; 878 F g⁻¹), cobalt molybdenum oxide (CMO; 690 F g⁻¹), NiO (350 F g⁻¹), and Co₃O₄ (259 F g⁻¹) electrodes, respectively. The electrochemical performances of HSCs, configured using the hierarchically structured ternary NCMO microflower and activated carbon (AC), respectively, are optimized by varying mass ratios of two electrodes. In particular, the NCMO//AC HSCs with 1:3 (D13) mass ratio exhibit the maximum energy and power densities of 51.22 W h kg⁻¹ and 41.67 kW kg⁻¹ with the high-capacitance retention of 89.29% over 20 000 cycles.