Designing a high-performance electrode leveraging dual-material synergy in a nanoarchitectural framework: Progressing towards supercapacitors with enhanced energy density

Exploring highly electroactive electrode materials with compatible nanostructures, tunable properties, and strong conductive networks is vital for supercapacitors (SCs). However, comprehending this complex area remains a significant challenge. In this work, we report the synthesis of a hierarchical NiCo₂O₄@NiMoO₄ (NCO@NMO) hybrid nanoarchitecture utilizing a cost-effective hydrothermal approach and subsequent annealing. This is achieved through facile and scalable in situ fabrication techniques that yield an electrode material suitable for advanced high-energy hybrid supercapacitors (HSCs). The unique hybrid nanoarchitecture is engineered to provide an effective, open-porous framework that facilitates ion diffusion and enables rapid electron transport. The NCO@NMO hybrid nanoarchitecture electrode exhibits a battery-type redox mechanism, achieving a peak specific capacitance of 1984 F g⁻¹ at a current density of 1 A g⁻¹ in an aqueous electrolyte, surpassing the performance of its individual components. Enhanced electrochemical performance is achieved by increasing the density of electroactive sites and conductivity through surface modifications, thereby facilitating rapid redox kinetics. Notably, the fabricated HSC device, with a configuration of NCO@NMO//activated carbon, demonstrates an impressive power density of 42.56 kW kg⁻¹, complemented by an energy density of 75.04 Wh kg⁻¹, and exhibits excellent cyclic stability, retaining up to 89.62 ± 1.19 % of its capacitance, even after 20,000 cycles. The high energy density and considerable cyclic stability are comparatively higher than those of conventional SCs and even approach the values of commercial batteries.